diff --git a/egs/ami/SURT/local/add_source_feats.py b/egs/ami/SURT/local/add_source_feats.py
new file mode 100755
index 000000000..0917b88a6
--- /dev/null
+++ b/egs/ami/SURT/local/add_source_feats.py
@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+# Copyright    2022  Johns Hopkins University        (authors: Desh Raj)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""
+This file adds source features as temporal arrays to the mixture manifests.
+It looks for manifests in the directory data/manifests.
+"""
+import logging
+from pathlib import Path
+
+import numpy as np
+from lhotse import CutSet, LilcomChunkyWriter, load_manifest, load_manifest_lazy
+from tqdm import tqdm
+
+
+def add_source_feats():
+    src_dir = Path("data/manifests")
+    output_dir = Path("data/fbank")
+
+    logging.info("Reading mixed cuts")
+    mixed_cuts_clean = load_manifest_lazy(src_dir / "cuts_train_clean.jsonl.gz")
+    mixed_cuts_reverb = load_manifest_lazy(src_dir / "cuts_train_reverb.jsonl.gz")
+
+    logging.info("Reading source cuts")
+    source_cuts = load_manifest(src_dir / "ihm_cuts_train_trimmed.jsonl.gz")
+
+    logging.info("Adding source features to the mixed cuts")
+    pbar = tqdm(total=len(mixed_cuts_clean), desc="Adding source features")
+    with CutSet.open_writer(
+        src_dir / "cuts_train_clean_sources.jsonl.gz"
+    ) as cut_writer_clean, CutSet.open_writer(
+        src_dir / "cuts_train_reverb_sources.jsonl.gz"
+    ) as cut_writer_reverb, LilcomChunkyWriter(
+        output_dir / "feats_train_clean_sources"
+    ) as source_feat_writer:
+        for cut_clean, cut_reverb in zip(mixed_cuts_clean, mixed_cuts_reverb):
+            assert cut_reverb.id == cut_clean.id + "_rvb"
+            source_feats = []
+            source_feat_offsets = []
+            cur_offset = 0
+            for sup in sorted(
+                cut_clean.supervisions, key=lambda s: (s.start, s.speaker)
+            ):
+                source_cut = source_cuts[sup.id]
+                source_feats.append(source_cut.load_features())
+                source_feat_offsets.append(cur_offset)
+                cur_offset += source_cut.num_frames
+            cut_clean.source_feats = source_feat_writer.store_array(
+                cut_clean.id, np.concatenate(source_feats, axis=0)
+            )
+            cut_clean.source_feat_offsets = source_feat_offsets
+            cut_writer_clean.write(cut_clean)
+            # Also write the reverb cut
+            cut_reverb.source_feats = cut_clean.source_feats
+            cut_reverb.source_feat_offsets = cut_clean.source_feat_offsets
+            cut_writer_reverb.write(cut_reverb)
+            pbar.update(1)
+
+
+if __name__ == "__main__":
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+    logging.basicConfig(format=formatter, level=logging.INFO)
+    add_source_feats()
diff --git a/egs/ami/SURT/local/compute_fbank_aimix.py b/egs/ami/SURT/local/compute_fbank_aimix.py
new file mode 100755
index 000000000..91b3a060b
--- /dev/null
+++ b/egs/ami/SURT/local/compute_fbank_aimix.py
@@ -0,0 +1,185 @@
+#!/usr/bin/env python3
+# Copyright    2022  Johns Hopkins University        (authors: Desh Raj)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""
+This file computes fbank features of the synthetically mixed AMI and ICSI
+train set.
+It looks for manifests in the directory data/manifests.
+
+The generated fbank features are saved in data/fbank.
+"""
+import logging
+import random
+import warnings
+from pathlib import Path
+
+import torch
+import torch.multiprocessing
+import torchaudio
+from lhotse import (
+    AudioSource,
+    LilcomChunkyWriter,
+    Recording,
+    load_manifest,
+    load_manifest_lazy,
+)
+from lhotse.audio import set_ffmpeg_torchaudio_info_enabled
+from lhotse.cut import MixedCut, MixTrack, MultiCut
+from lhotse.features.kaldifeat import (
+    KaldifeatFbank,
+    KaldifeatFbankConfig,
+    KaldifeatFrameOptions,
+    KaldifeatMelOptions,
+)
+from lhotse.utils import fix_random_seed, uuid4
+from tqdm import tqdm
+
+# Torch's multithreaded behavior needs to be disabled or
+# it wastes a lot of CPU and slow things down.
+# Do this outside of main() in case it needs to take effect
+# even when we are not invoking the main (e.g. when spawning subprocesses).
+torch.set_num_threads(1)
+torch.set_num_interop_threads(1)
+torch.multiprocessing.set_sharing_strategy("file_system")
+torchaudio.set_audio_backend("soundfile")
+set_ffmpeg_torchaudio_info_enabled(False)
+
+
+def compute_fbank_aimix():
+    src_dir = Path("data/manifests")
+    output_dir = Path("data/fbank")
+
+    sampling_rate = 16000
+    num_mel_bins = 80
+
+    extractor = KaldifeatFbank(
+        KaldifeatFbankConfig(
+            frame_opts=KaldifeatFrameOptions(sampling_rate=sampling_rate),
+            mel_opts=KaldifeatMelOptions(num_bins=num_mel_bins),
+            device="cuda",
+        )
+    )
+
+    logging.info("Reading manifests")
+    train_cuts = load_manifest_lazy(src_dir / "ai-mix_cuts_clean_full.jsonl.gz")
+
+    # only uses RIRs and noises from REVERB challenge
+    real_rirs = load_manifest(src_dir / "real-rir_recordings_all.jsonl.gz").filter(
+        lambda r: "RVB2014" in r.id
+    )
+    noises = load_manifest(src_dir / "iso-noise_recordings_all.jsonl.gz").filter(
+        lambda r: "RVB2014" in r.id
+    )
+
+    # Apply perturbation to the training cuts
+    logging.info("Applying perturbation to the training cuts")
+    train_cuts_rvb = train_cuts.map(
+        lambda c: augment(
+            c, perturb_snr=True, rirs=real_rirs, noises=noises, perturb_loudness=True
+        )
+    )
+
+    logging.info("Extracting fbank features for training cuts")
+    _ = train_cuts.compute_and_store_features_batch(
+        extractor=extractor,
+        storage_path=output_dir / "ai-mix_feats_clean",
+        manifest_path=src_dir / "cuts_train_clean.jsonl.gz",
+        batch_duration=5000,
+        num_workers=4,
+        storage_type=LilcomChunkyWriter,
+        overwrite=True,
+    )
+
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore")
+        _ = train_cuts_rvb.compute_and_store_features_batch(
+            extractor=extractor,
+            storage_path=output_dir / "ai-mix_feats_reverb",
+            manifest_path=src_dir / "cuts_train_reverb.jsonl.gz",
+            batch_duration=5000,
+            num_workers=4,
+            storage_type=LilcomChunkyWriter,
+            overwrite=True,
+        )
+
+
+def augment(cut, perturb_snr=False, rirs=None, noises=None, perturb_loudness=False):
+    """
+    Given a mixed cut, this function optionally applies the following augmentations:
+    - Perturbing the SNRs of the tracks (in range [-5, 5] dB)
+    - Reverberation using a randomly selected RIR
+    - Adding noise
+    - Perturbing the loudness (in range [-20, -25] dB)
+    """
+    out_cut = cut.drop_features()
+
+    # Perturb the SNRs (optional)
+    if perturb_snr:
+        snrs = [random.uniform(-5, 5) for _ in range(len(cut.tracks))]
+        for i, (track, snr) in enumerate(zip(out_cut.tracks, snrs)):
+            if i == 0:
+                # Skip the first track since it is the reference
+                continue
+            track.snr = snr
+
+    # Reverberate the cut (optional)
+    if rirs is not None:
+        # Select an RIR at random
+        rir = random.choice(rirs)
+        # Select a channel at random
+        rir_channel = random.choice(list(range(rir.num_channels)))
+        # Reverberate the cut
+        out_cut = out_cut.reverb_rir(rir_recording=rir, rir_channels=[rir_channel])
+
+    # Add noise (optional)
+    if noises is not None:
+        # Select a noise recording at random
+        noise = random.choice(noises).to_cut()
+        if isinstance(noise, MultiCut):
+            noise = noise.to_mono()[0]
+        # Select an SNR at random
+        snr = random.uniform(10, 30)
+        # Repeat the noise to match the duration of the cut
+        noise = repeat_cut(noise, out_cut.duration)
+        out_cut = MixedCut(
+            id=out_cut.id,
+            tracks=[
+                MixTrack(cut=out_cut, type="MixedCut"),
+                MixTrack(cut=noise, type="DataCut", snr=snr),
+            ],
+        )
+
+    # Perturb the loudness (optional)
+    if perturb_loudness:
+        target_loudness = random.uniform(-20, -25)
+        out_cut = out_cut.normalize_loudness(target_loudness, mix_first=True)
+    return out_cut
+
+
+def repeat_cut(cut, duration):
+    while cut.duration < duration:
+        cut = cut.mix(cut, offset_other_by=cut.duration)
+    return cut.truncate(duration=duration)
+
+
+if __name__ == "__main__":
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+    logging.basicConfig(format=formatter, level=logging.INFO)
+
+    fix_random_seed(42)
+    compute_fbank_aimix()
diff --git a/egs/ami/SURT/local/compute_fbank_ami.py b/egs/ami/SURT/local/compute_fbank_ami.py
new file mode 100755
index 000000000..351b41765
--- /dev/null
+++ b/egs/ami/SURT/local/compute_fbank_ami.py
@@ -0,0 +1,94 @@
+#!/usr/bin/env python3
+# Copyright    2022  Johns Hopkins University        (authors: Desh Raj)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""
+This file computes fbank features of the AMI dataset.
+We compute features for full recordings (i.e., without trimming to supervisions).
+This way we can create arbitrary segmentations later.
+
+The generated fbank features are saved in data/fbank.
+"""
+import logging
+import math
+from pathlib import Path
+
+import torch
+import torch.multiprocessing
+from lhotse import CutSet, LilcomChunkyWriter
+from lhotse.features.kaldifeat import (
+    KaldifeatFbank,
+    KaldifeatFbankConfig,
+    KaldifeatFrameOptions,
+    KaldifeatMelOptions,
+)
+from lhotse.recipes.utils import read_manifests_if_cached
+
+# Torch's multithreaded behavior needs to be disabled or
+# it wastes a lot of CPU and slow things down.
+# Do this outside of main() in case it needs to take effect
+# even when we are not invoking the main (e.g. when spawning subprocesses).
+torch.set_num_threads(1)
+torch.set_num_interop_threads(1)
+torch.multiprocessing.set_sharing_strategy("file_system")
+
+
+def compute_fbank_ami():
+    src_dir = Path("data/manifests")
+    output_dir = Path("data/fbank")
+
+    sampling_rate = 16000
+    num_mel_bins = 80
+
+    extractor = KaldifeatFbank(
+        KaldifeatFbankConfig(
+            frame_opts=KaldifeatFrameOptions(sampling_rate=sampling_rate),
+            mel_opts=KaldifeatMelOptions(num_bins=num_mel_bins),
+            device="cuda",
+        )
+    )
+
+    logging.info("Reading manifests")
+    manifests = {}
+    for part in ["ihm-mix", "sdm", "mdm8-bf"]:
+        manifests[part] = read_manifests_if_cached(
+            dataset_parts=["train", "dev", "test"],
+            output_dir=src_dir,
+            prefix=f"ami-{part}",
+            suffix="jsonl.gz",
+        )
+
+    for part in ["ihm-mix", "sdm", "mdm8-bf"]:
+        for split in ["train", "dev", "test"]:
+            logging.info(f"Processing {part} {split}")
+            cuts = CutSet.from_manifests(
+                **manifests[part][split]
+            ).compute_and_store_features_batch(
+                extractor=extractor,
+                storage_path=output_dir / f"ami-{part}_{split}_feats",
+                manifest_path=src_dir / f"cuts_ami-{part}_{split}.jsonl.gz",
+                batch_duration=5000,
+                num_workers=4,
+                storage_type=LilcomChunkyWriter,
+            )
+
+
+if __name__ == "__main__":
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+    logging.basicConfig(format=formatter, level=logging.INFO)
+
+    compute_fbank_ami()
diff --git a/egs/ami/SURT/local/compute_fbank_icsi.py b/egs/ami/SURT/local/compute_fbank_icsi.py
new file mode 100755
index 000000000..4e2ff3f3b
--- /dev/null
+++ b/egs/ami/SURT/local/compute_fbank_icsi.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+# Copyright    2022  Johns Hopkins University        (authors: Desh Raj)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""
+This file computes fbank features of the ICSI dataset.
+We compute features for full recordings (i.e., without trimming to supervisions).
+This way we can create arbitrary segmentations later.
+
+The generated fbank features are saved in data/fbank.
+"""
+import logging
+import math
+from pathlib import Path
+
+import torch
+import torch.multiprocessing
+from lhotse import CutSet, LilcomChunkyWriter
+from lhotse.features.kaldifeat import (
+    KaldifeatFbank,
+    KaldifeatFbankConfig,
+    KaldifeatFrameOptions,
+    KaldifeatMelOptions,
+)
+from lhotse.recipes.utils import read_manifests_if_cached
+
+# Torch's multithreaded behavior needs to be disabled or
+# it wastes a lot of CPU and slow things down.
+# Do this outside of main() in case it needs to take effect
+# even when we are not invoking the main (e.g. when spawning subprocesses).
+torch.set_num_threads(1)
+torch.set_num_interop_threads(1)
+torch.multiprocessing.set_sharing_strategy("file_system")
+
+
+def compute_fbank_icsi():
+    src_dir = Path("data/manifests")
+    output_dir = Path("data/fbank")
+
+    sampling_rate = 16000
+    num_mel_bins = 80
+
+    extractor = KaldifeatFbank(
+        KaldifeatFbankConfig(
+            frame_opts=KaldifeatFrameOptions(sampling_rate=sampling_rate),
+            mel_opts=KaldifeatMelOptions(num_bins=num_mel_bins),
+            device="cuda",
+        )
+    )
+
+    logging.info("Reading manifests")
+    manifests = {}
+    for part in ["ihm-mix", "sdm"]:
+        manifests[part] = read_manifests_if_cached(
+            dataset_parts=["train"],
+            output_dir=src_dir,
+            prefix=f"icsi-{part}",
+            suffix="jsonl.gz",
+        )
+
+    for part in ["ihm-mix", "sdm"]:
+        for split in ["train"]:
+            logging.info(f"Processing {part} {split}")
+            cuts = CutSet.from_manifests(
+                **manifests[part][split]
+            ).compute_and_store_features_batch(
+                extractor=extractor,
+                storage_path=output_dir / f"icsi-{part}_{split}_feats",
+                manifest_path=src_dir / f"cuts_icsi-{part}_{split}.jsonl.gz",
+                batch_duration=5000,
+                num_workers=4,
+                storage_type=LilcomChunkyWriter,
+                overwrite=True,
+            )
+
+
+if __name__ == "__main__":
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+    logging.basicConfig(format=formatter, level=logging.INFO)
+
+    compute_fbank_icsi()
diff --git a/egs/ami/SURT/local/compute_fbank_ihm.py b/egs/ami/SURT/local/compute_fbank_ihm.py
new file mode 100755
index 000000000..56f54aa21
--- /dev/null
+++ b/egs/ami/SURT/local/compute_fbank_ihm.py
@@ -0,0 +1,101 @@
+#!/usr/bin/env python3
+# Copyright    2022  Johns Hopkins University        (authors: Desh Raj)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""
+This file computes fbank features of the trimmed sub-segments which will be
+used for simulating the training mixtures.
+
+The generated fbank features are saved in data/fbank.
+"""
+import logging
+import math
+from pathlib import Path
+
+import torch
+import torch.multiprocessing
+import torchaudio
+from lhotse import CutSet, LilcomChunkyWriter, load_manifest
+from lhotse.audio import set_ffmpeg_torchaudio_info_enabled
+from lhotse.features.kaldifeat import (
+    KaldifeatFbank,
+    KaldifeatFbankConfig,
+    KaldifeatFrameOptions,
+    KaldifeatMelOptions,
+)
+from lhotse.recipes.utils import read_manifests_if_cached
+from tqdm import tqdm
+
+# Torch's multithreaded behavior needs to be disabled or
+# it wastes a lot of CPU and slow things down.
+# Do this outside of main() in case it needs to take effect
+# even when we are not invoking the main (e.g. when spawning subprocesses).
+torch.set_num_threads(1)
+torch.set_num_interop_threads(1)
+torch.multiprocessing.set_sharing_strategy("file_system")
+torchaudio.set_audio_backend("soundfile")
+set_ffmpeg_torchaudio_info_enabled(False)
+
+
+def compute_fbank_ihm():
+    src_dir = Path("data/manifests")
+    output_dir = Path("data/fbank")
+
+    sampling_rate = 16000
+    num_mel_bins = 80
+
+    extractor = KaldifeatFbank(
+        KaldifeatFbankConfig(
+            frame_opts=KaldifeatFrameOptions(sampling_rate=sampling_rate),
+            mel_opts=KaldifeatMelOptions(num_bins=num_mel_bins),
+            device="cuda",
+        )
+    )
+
+    logging.info("Reading manifests")
+    manifests = {}
+    for data in ["ami", "icsi"]:
+        manifests[data] = read_manifests_if_cached(
+            dataset_parts=["train"],
+            output_dir=src_dir,
+            types=["recordings", "supervisions"],
+            prefix=f"{data}-ihm",
+            suffix="jsonl.gz",
+        )
+
+    logging.info("Computing features")
+    for data in ["ami", "icsi"]:
+        cs = CutSet.from_manifests(**manifests[data]["train"])
+        cs = cs.trim_to_supervisions(keep_overlapping=False)
+        cs = cs.normalize_loudness(target=-23.0, affix_id=False)
+        cs = cs + cs.perturb_speed(0.9) + cs.perturb_speed(1.1)
+        _ = cs.compute_and_store_features_batch(
+            extractor=extractor,
+            storage_path=output_dir / f"{data}-ihm_train_feats",
+            manifest_path=src_dir / f"{data}-ihm_cuts_train.jsonl.gz",
+            batch_duration=5000,
+            num_workers=4,
+            storage_type=LilcomChunkyWriter,
+            overwrite=True,
+        )
+
+
+if __name__ == "__main__":
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+    logging.basicConfig(format=formatter, level=logging.INFO)
+
+    compute_fbank_ihm()
diff --git a/egs/ami/SURT/local/prepare_ami_train_cuts.py b/egs/ami/SURT/local/prepare_ami_train_cuts.py
new file mode 100755
index 000000000..72fced70d
--- /dev/null
+++ b/egs/ami/SURT/local/prepare_ami_train_cuts.py
@@ -0,0 +1,146 @@
+#!/usr/bin/env python3
+# Copyright    2022  Johns Hopkins University        (authors: Desh Raj)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""
+This file creates AMI train segments.
+"""
+import logging
+import math
+from pathlib import Path
+
+import torch
+import torch.multiprocessing
+from lhotse import LilcomChunkyWriter, load_manifest_lazy
+from lhotse.cut import Cut, CutSet
+from lhotse.utils import EPSILON, add_durations
+from tqdm import tqdm
+
+
+def cut_into_windows(cuts: CutSet, duration: float):
+    """
+    This function takes a CutSet and cuts each cut into windows of roughly
+    `duration` seconds. By roughly, we mean that we try to adjust for the last supervision
+    that exceeds the duration, or is shorter than the duration.
+    """
+    res = []
+    with tqdm() as pbar:
+        for cut in cuts:
+            pbar.update(1)
+            sups = cut.index_supervisions()[cut.id]
+            sr = cut.sampling_rate
+            start = 0.0
+            end = duration
+            num_tries = 0
+            while start < cut.duration and num_tries < 2:
+                # Find the supervision that are cut by the window endpoint
+                hitlist = [iv for iv in sups.at(end) if iv.begin < end]
+                # If there are no supervisions, we are done
+                if not hitlist:
+                    res.append(
+                        cut.truncate(
+                            offset=start,
+                            duration=add_durations(end, -start, sampling_rate=sr),
+                            keep_excessive_supervisions=False,
+                        )
+                    )
+                    # Update the start and end for the next window
+                    start = end
+                    end = add_durations(end, duration, sampling_rate=sr)
+                else:
+                    # find ratio of durations cut by the window endpoint
+                    ratios = [
+                        add_durations(end, -iv.end, sampling_rate=sr) / iv.length()
+                        for iv in hitlist
+                    ]
+                    # we retain the supervisions that have >50% of their duration
+                    # in the window, and discard the others
+                    retained = []
+                    discarded = []
+                    for iv, ratio in zip(hitlist, ratios):
+                        if ratio > 0.5:
+                            retained.append(iv)
+                        else:
+                            discarded.append(iv)
+                    cur_end = max(iv.end for iv in retained) if retained else end
+                    res.append(
+                        cut.truncate(
+                            offset=start,
+                            duration=add_durations(cur_end, -start, sampling_rate=sr),
+                            keep_excessive_supervisions=False,
+                        )
+                    )
+                    # For the next window, we start at the earliest discarded supervision
+                    next_start = min(iv.begin for iv in discarded) if discarded else end
+                    next_end = add_durations(next_start, duration, sampling_rate=sr)
+                    # It may happen that next_start is the same as start, in which case
+                    # we will advance the window anyway
+                    if next_start == start:
+                        logging.warning(
+                            f"Next start is the same as start: {next_start} == {start} for cut {cut.id}"
+                        )
+                        start = end + EPSILON
+                        end = add_durations(start, duration, sampling_rate=sr)
+                        num_tries += 1
+                    else:
+                        start = next_start
+                        end = next_end
+    return CutSet.from_cuts(res)
+
+
+def prepare_train_cuts():
+    src_dir = Path("data/manifests")
+
+    logging.info("Loading the manifests")
+    train_cuts_ihm = load_manifest_lazy(
+        src_dir / "cuts_ami-ihm-mix_train.jsonl.gz"
+    ).map(lambda c: c.with_id(f"{c.id}_ihm-mix"))
+    train_cuts_sdm = load_manifest_lazy(src_dir / "cuts_ami-sdm_train.jsonl.gz").map(
+        lambda c: c.with_id(f"{c.id}_sdm")
+    )
+    train_cuts_mdm = load_manifest_lazy(
+        src_dir / "cuts_ami-mdm8-bf_train.jsonl.gz"
+    ).map(lambda c: c.with_id(f"{c.id}_mdm8-bf"))
+
+    # Combine all cuts into one CutSet
+    train_cuts = train_cuts_ihm + train_cuts_sdm + train_cuts_mdm
+
+    train_cuts_1 = train_cuts.trim_to_supervision_groups(max_pause=0.5)
+    train_cuts_2 = train_cuts.trim_to_supervision_groups(max_pause=0.0)
+
+    # Combine the two segmentations
+    train_all = train_cuts_1 + train_cuts_2
+
+    # At this point, some of the cuts may be very long. We will cut them into windows of
+    # roughly 30 seconds.
+    logging.info("Cutting the segments into windows of 30 seconds")
+    train_all_30 = cut_into_windows(train_all, duration=30.0)
+    logging.info(f"Number of cuts after cutting into windows: {len(train_all_30)}")
+
+    # Show statistics
+    train_all.describe(full=True)
+
+    # Save the cuts
+    logging.info("Saving the cuts")
+    train_all.to_file(src_dir / "cuts_train_ami.jsonl.gz")
+
+
+if __name__ == "__main__":
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+    logging.basicConfig(format=formatter, level=logging.INFO)
+
+    prepare_train_cuts()
diff --git a/egs/ami/SURT/local/prepare_icsi_train_cuts.py b/egs/ami/SURT/local/prepare_icsi_train_cuts.py
new file mode 100755
index 000000000..818e26bfb
--- /dev/null
+++ b/egs/ami/SURT/local/prepare_icsi_train_cuts.py
@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+# Copyright    2022  Johns Hopkins University        (authors: Desh Raj)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""
+This file creates ICSI train segments.
+"""
+import logging
+from pathlib import Path
+
+from lhotse import load_manifest_lazy
+from prepare_ami_train_cuts import cut_into_windows
+
+
+def prepare_train_cuts():
+    src_dir = Path("data/manifests")
+
+    logging.info("Loading the manifests")
+    train_cuts_ihm = load_manifest_lazy(
+        src_dir / "cuts_icsi-ihm-mix_train.jsonl.gz"
+    ).map(lambda c: c.with_id(f"{c.id}_ihm-mix"))
+    train_cuts_sdm = load_manifest_lazy(src_dir / "cuts_icsi-sdm_train.jsonl.gz").map(
+        lambda c: c.with_id(f"{c.id}_sdm")
+    )
+
+    # Combine all cuts into one CutSet
+    train_cuts = train_cuts_ihm + train_cuts_sdm
+
+    train_cuts_1 = train_cuts.trim_to_supervision_groups(max_pause=0.5)
+    train_cuts_2 = train_cuts.trim_to_supervision_groups(max_pause=0.0)
+
+    # Combine the two segmentations
+    train_all = train_cuts_1 + train_cuts_2
+
+    # At this point, some of the cuts may be very long. We will cut them into windows of
+    # roughly 30 seconds.
+    logging.info("Cutting the segments into windows of 30 seconds")
+    train_all_30 = cut_into_windows(train_all, duration=30.0)
+    logging.info(f"Number of cuts after cutting into windows: {len(train_all_30)}")
+
+    # Show statistics
+    train_all.describe(full=True)
+
+    # Save the cuts
+    logging.info("Saving the cuts")
+    train_all.to_file(src_dir / "cuts_train_icsi.jsonl.gz")
+
+
+if __name__ == "__main__":
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+    logging.basicConfig(format=formatter, level=logging.INFO)
+
+    prepare_train_cuts()
diff --git a/egs/ami/SURT/local/prepare_lang.py b/egs/ami/SURT/local/prepare_lang.py
new file mode 100755
index 000000000..d913756a1
--- /dev/null
+++ b/egs/ami/SURT/local/prepare_lang.py
@@ -0,0 +1,413 @@
+#!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""
+This script takes as input a lexicon file "data/lang_phone/lexicon.txt"
+consisting of words and tokens (i.e., phones) and does the following:
+
+1. Add disambiguation symbols to the lexicon and generate lexicon_disambig.txt
+
+2. Generate tokens.txt, the token table mapping a token to a unique integer.
+
+3. Generate words.txt, the word table mapping a word to a unique integer.
+
+4. Generate L.pt, in k2 format. It can be loaded by
+
+        d = torch.load("L.pt")
+        lexicon = k2.Fsa.from_dict(d)
+
+5. Generate L_disambig.pt, in k2 format.
+"""
+import argparse
+import math
+from collections import defaultdict
+from pathlib import Path
+from typing import Any, Dict, List, Tuple
+
+import k2
+import torch
+
+from icefall.lexicon import read_lexicon, write_lexicon
+from icefall.utils import str2bool
+
+Lexicon = List[Tuple[str, List[str]]]
+
+
+def get_args():
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "--lang-dir",
+        type=str,
+        help="""Input and output directory.
+        It should contain a file lexicon.txt.
+        Generated files by this script are saved into this directory.
+        """,
+    )
+
+    parser.add_argument(
+        "--debug",
+        type=str2bool,
+        default=False,
+        help="""True for debugging, which will generate
+        a visualization of the lexicon FST.
+
+        Caution: If your lexicon contains hundreds of thousands
+        of lines, please set it to False!
+        """,
+    )
+
+    return parser.parse_args()
+
+
+def write_mapping(filename: str, sym2id: Dict[str, int]) -> None:
+    """Write a symbol to ID mapping to a file.
+
+    Note:
+      No need to implement `read_mapping` as it can be done
+      through :func:`k2.SymbolTable.from_file`.
+
+    Args:
+      filename:
+        Filename to save the mapping.
+      sym2id:
+        A dict mapping symbols to IDs.
+    Returns:
+      Return None.
+    """
+    with open(filename, "w", encoding="utf-8") as f:
+        for sym, i in sym2id.items():
+            f.write(f"{sym} {i}\n")
+
+
+def get_tokens(lexicon: Lexicon) -> List[str]:
+    """Get tokens from a lexicon.
+
+    Args:
+      lexicon:
+        It is the return value of :func:`read_lexicon`.
+    Returns:
+      Return a list of unique tokens.
+    """
+    ans = set()
+    for _, tokens in lexicon:
+        ans.update(tokens)
+    sorted_ans = sorted(list(ans))
+    return sorted_ans
+
+
+def get_words(lexicon: Lexicon) -> List[str]:
+    """Get words from a lexicon.
+
+    Args:
+      lexicon:
+        It is the return value of :func:`read_lexicon`.
+    Returns:
+      Return a list of unique words.
+    """
+    ans = set()
+    for word, _ in lexicon:
+        ans.add(word)
+    sorted_ans = sorted(list(ans))
+    return sorted_ans
+
+
+def add_disambig_symbols(lexicon: Lexicon) -> Tuple[Lexicon, int]:
+    """It adds pseudo-token disambiguation symbols #1, #2 and so on
+    at the ends of tokens to ensure that all pronunciations are different,
+    and that none is a prefix of another.
+
+    See also add_lex_disambig.pl from kaldi.
+
+    Args:
+      lexicon:
+        It is returned by :func:`read_lexicon`.
+    Returns:
+      Return a tuple with two elements:
+
+        - The output lexicon with disambiguation symbols
+        - The ID of the max disambiguation symbol that appears
+          in the lexicon
+    """
+
+    # (1) Work out the count of each token-sequence in the
+    # lexicon.
+    count = defaultdict(int)
+    for _, tokens in lexicon:
+        count[" ".join(tokens)] += 1
+
+    # (2) For each left sub-sequence of each token-sequence, note down
+    # that it exists (for identifying prefixes of longer strings).
+    issubseq = defaultdict(int)
+    for _, tokens in lexicon:
+        tokens = tokens.copy()
+        tokens.pop()
+        while tokens:
+            issubseq[" ".join(tokens)] = 1
+            tokens.pop()
+
+    # (3) For each entry in the lexicon:
+    # if the token sequence is unique and is not a
+    # prefix of another word, no disambig symbol.
+    # Else output #1, or #2, #3, ... if the same token-seq
+    # has already been assigned a disambig symbol.
+    ans = []
+
+    # We start with #1 since #0 has its own purpose
+    first_allowed_disambig = 1
+    max_disambig = first_allowed_disambig - 1
+    last_used_disambig_symbol_of = defaultdict(int)
+
+    for word, tokens in lexicon:
+        tokenseq = " ".join(tokens)
+        assert tokenseq != ""
+        if issubseq[tokenseq] == 0 and count[tokenseq] == 1:
+            ans.append((word, tokens))
+            continue
+
+        cur_disambig = last_used_disambig_symbol_of[tokenseq]
+        if cur_disambig == 0:
+            cur_disambig = first_allowed_disambig
+        else:
+            cur_disambig += 1
+
+        if cur_disambig > max_disambig:
+            max_disambig = cur_disambig
+        last_used_disambig_symbol_of[tokenseq] = cur_disambig
+        tokenseq += f" #{cur_disambig}"
+        ans.append((word, tokenseq.split()))
+    return ans, max_disambig
+
+
+def generate_id_map(symbols: List[str]) -> Dict[str, int]:
+    """Generate ID maps, i.e., map a symbol to a unique ID.
+
+    Args:
+      symbols:
+        A list of unique symbols.
+    Returns:
+      A dict containing the mapping between symbols and IDs.
+    """
+    return {sym: i for i, sym in enumerate(symbols)}
+
+
+def add_self_loops(
+    arcs: List[List[Any]], disambig_token: int, disambig_word: int
+) -> List[List[Any]]:
+    """Adds self-loops to states of an FST to propagate disambiguation symbols
+    through it. They are added on each state with non-epsilon output symbols
+    on at least one arc out of the state.
+
+    See also fstaddselfloops.pl from Kaldi. One difference is that
+    Kaldi uses OpenFst style FSTs and it has multiple final states.
+    This function uses k2 style FSTs and it does not need to add self-loops
+    to the final state.
+
+    The input label of a self-loop is `disambig_token`, while the output
+    label is `disambig_word`.
+
+    Args:
+      arcs:
+        A list-of-list. The sublist contains
+        `[src_state, dest_state, label, aux_label, score]`
+      disambig_token:
+        It is the token ID of the symbol `#0`.
+      disambig_word:
+        It is the word ID of the symbol `#0`.
+
+    Return:
+      Return new `arcs` containing self-loops.
+    """
+    states_needs_self_loops = set()
+    for arc in arcs:
+        src, dst, ilabel, olabel, score = arc
+        if olabel != 0:
+            states_needs_self_loops.add(src)
+
+    ans = []
+    for s in states_needs_self_loops:
+        ans.append([s, s, disambig_token, disambig_word, 0])
+
+    return arcs + ans
+
+
+def lexicon_to_fst(
+    lexicon: Lexicon,
+    token2id: Dict[str, int],
+    word2id: Dict[str, int],
+    sil_token: str = "SIL",
+    sil_prob: float = 0.5,
+    need_self_loops: bool = False,
+) -> k2.Fsa:
+    """Convert a lexicon to an FST (in k2 format) with optional silence at
+    the beginning and end of each word.
+
+    Args:
+      lexicon:
+        The input lexicon. See also :func:`read_lexicon`
+      token2id:
+        A dict mapping tokens to IDs.
+      word2id:
+        A dict mapping words to IDs.
+      sil_token:
+        The silence token.
+      sil_prob:
+        The probability for adding a silence at the beginning and end
+        of the word.
+      need_self_loops:
+        If True, add self-loop to states with non-epsilon output symbols
+        on at least one arc out of the state. The input label for this
+        self loop is `token2id["#0"]` and the output label is `word2id["#0"]`.
+    Returns:
+      Return an instance of `k2.Fsa` representing the given lexicon.
+    """
+    assert sil_prob > 0.0 and sil_prob < 1.0
+    # CAUTION: we use score, i.e, negative cost.
+    sil_score = math.log(sil_prob)
+    no_sil_score = math.log(1.0 - sil_prob)
+
+    start_state = 0
+    loop_state = 1  # words enter and leave from here
+    sil_state = 2  # words terminate here when followed by silence; this state
+    # has a silence transition to loop_state.
+    next_state = 3  # the next un-allocated state, will be incremented as we go.
+    arcs = []
+
+    assert token2id["<eps>"] == 0
+    assert word2id["<eps>"] == 0
+
+    eps = 0
+
+    sil_token = token2id[sil_token]
+
+    arcs.append([start_state, loop_state, eps, eps, no_sil_score])
+    arcs.append([start_state, sil_state, eps, eps, sil_score])
+    arcs.append([sil_state, loop_state, sil_token, eps, 0])
+
+    for word, tokens in lexicon:
+        assert len(tokens) > 0, f"{word} has no pronunciations"
+        cur_state = loop_state
+
+        word = word2id[word]
+        tokens = [token2id[i] for i in tokens]
+
+        for i in range(len(tokens) - 1):
+            w = word if i == 0 else eps
+            arcs.append([cur_state, next_state, tokens[i], w, 0])
+
+            cur_state = next_state
+            next_state += 1
+
+        # now for the last token of this word
+        # It has two out-going arcs, one to the loop state,
+        # the other one to the sil_state.
+        i = len(tokens) - 1
+        w = word if i == 0 else eps
+        arcs.append([cur_state, loop_state, tokens[i], w, no_sil_score])
+        arcs.append([cur_state, sil_state, tokens[i], w, sil_score])
+
+    if need_self_loops:
+        disambig_token = token2id["#0"]
+        disambig_word = word2id["#0"]
+        arcs = add_self_loops(
+            arcs,
+            disambig_token=disambig_token,
+            disambig_word=disambig_word,
+        )
+
+    final_state = next_state
+    arcs.append([loop_state, final_state, -1, -1, 0])
+    arcs.append([final_state])
+
+    arcs = sorted(arcs, key=lambda arc: arc[0])
+    arcs = [[str(i) for i in arc] for arc in arcs]
+    arcs = [" ".join(arc) for arc in arcs]
+    arcs = "\n".join(arcs)
+
+    fsa = k2.Fsa.from_str(arcs, acceptor=False)
+    return fsa
+
+
+def main():
+    args = get_args()
+    lang_dir = Path(args.lang_dir)
+    lexicon_filename = lang_dir / "lexicon.txt"
+    sil_token = "SIL"
+    sil_prob = 0.5
+
+    lexicon = read_lexicon(lexicon_filename)
+    tokens = get_tokens(lexicon)
+    words = get_words(lexicon)
+
+    lexicon_disambig, max_disambig = add_disambig_symbols(lexicon)
+
+    for i in range(max_disambig + 1):
+        disambig = f"#{i}"
+        assert disambig not in tokens
+        tokens.append(f"#{i}")
+
+    assert "<eps>" not in tokens
+    tokens = ["<eps>"] + tokens
+
+    assert "<eps>" not in words
+    assert "#0" not in words
+    assert "<s>" not in words
+    assert "</s>" not in words
+
+    words = ["<eps>"] + words + ["#0", "<s>", "</s>"]
+
+    token2id = generate_id_map(tokens)
+    word2id = generate_id_map(words)
+
+    write_mapping(lang_dir / "tokens.txt", token2id)
+    write_mapping(lang_dir / "words.txt", word2id)
+    write_lexicon(lang_dir / "lexicon_disambig.txt", lexicon_disambig)
+
+    L = lexicon_to_fst(
+        lexicon,
+        token2id=token2id,
+        word2id=word2id,
+        sil_token=sil_token,
+        sil_prob=sil_prob,
+    )
+
+    L_disambig = lexicon_to_fst(
+        lexicon_disambig,
+        token2id=token2id,
+        word2id=word2id,
+        sil_token=sil_token,
+        sil_prob=sil_prob,
+        need_self_loops=True,
+    )
+    torch.save(L.as_dict(), lang_dir / "L.pt")
+    torch.save(L_disambig.as_dict(), lang_dir / "L_disambig.pt")
+
+    if args.debug:
+        labels_sym = k2.SymbolTable.from_file(lang_dir / "tokens.txt")
+        aux_labels_sym = k2.SymbolTable.from_file(lang_dir / "words.txt")
+
+        L.labels_sym = labels_sym
+        L.aux_labels_sym = aux_labels_sym
+        L.draw(f"{lang_dir / 'L.svg'}", title="L.pt")
+
+        L_disambig.labels_sym = labels_sym
+        L_disambig.aux_labels_sym = aux_labels_sym
+        L_disambig.draw(f"{lang_dir / 'L_disambig.svg'}", title="L_disambig.pt")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/egs/ami/SURT/local/prepare_lang_bpe.py b/egs/ami/SURT/local/prepare_lang_bpe.py
new file mode 100755
index 000000000..2a2d9c219
--- /dev/null
+++ b/egs/ami/SURT/local/prepare_lang_bpe.py
@@ -0,0 +1,266 @@
+#!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+# Copyright (c)  2021  Xiaomi Corporation (authors: Fangjun Kuang)
+
+"""
+
+This script takes as input `lang_dir`, which should contain::
+
+    - lang_dir/bpe.model,
+    - lang_dir/words.txt
+
+and generates the following files in the directory `lang_dir`:
+
+    - lexicon.txt
+    - lexicon_disambig.txt
+    - L.pt
+    - L_disambig.pt
+    - tokens.txt
+"""
+
+import argparse
+from pathlib import Path
+from typing import Dict, List, Tuple
+
+import k2
+import sentencepiece as spm
+import torch
+from prepare_lang import (
+    Lexicon,
+    add_disambig_symbols,
+    add_self_loops,
+    write_lexicon,
+    write_mapping,
+)
+
+from icefall.utils import str2bool
+
+
+def lexicon_to_fst_no_sil(
+    lexicon: Lexicon,
+    token2id: Dict[str, int],
+    word2id: Dict[str, int],
+    need_self_loops: bool = False,
+) -> k2.Fsa:
+    """Convert a lexicon to an FST (in k2 format).
+
+    Args:
+      lexicon:
+        The input lexicon. See also :func:`read_lexicon`
+      token2id:
+        A dict mapping tokens to IDs.
+      word2id:
+        A dict mapping words to IDs.
+      need_self_loops:
+        If True, add self-loop to states with non-epsilon output symbols
+        on at least one arc out of the state. The input label for this
+        self loop is `token2id["#0"]` and the output label is `word2id["#0"]`.
+    Returns:
+      Return an instance of `k2.Fsa` representing the given lexicon.
+    """
+    loop_state = 0  # words enter and leave from here
+    next_state = 1  # the next un-allocated state, will be incremented as we go
+
+    arcs = []
+
+    # The blank symbol <blk> is defined in local/train_bpe_model.py
+    assert token2id["<blk>"] == 0
+    assert word2id["<eps>"] == 0
+
+    eps = 0
+
+    for word, pieces in lexicon:
+        assert len(pieces) > 0, f"{word} has no pronunciations"
+        cur_state = loop_state
+
+        word = word2id[word]
+        pieces = [token2id[i] for i in pieces]
+
+        for i in range(len(pieces) - 1):
+            w = word if i == 0 else eps
+            arcs.append([cur_state, next_state, pieces[i], w, 0])
+
+            cur_state = next_state
+            next_state += 1
+
+        # now for the last piece of this word
+        i = len(pieces) - 1
+        w = word if i == 0 else eps
+        arcs.append([cur_state, loop_state, pieces[i], w, 0])
+
+    if need_self_loops:
+        disambig_token = token2id["#0"]
+        disambig_word = word2id["#0"]
+        arcs = add_self_loops(
+            arcs,
+            disambig_token=disambig_token,
+            disambig_word=disambig_word,
+        )
+
+    final_state = next_state
+    arcs.append([loop_state, final_state, -1, -1, 0])
+    arcs.append([final_state])
+
+    arcs = sorted(arcs, key=lambda arc: arc[0])
+    arcs = [[str(i) for i in arc] for arc in arcs]
+    arcs = [" ".join(arc) for arc in arcs]
+    arcs = "\n".join(arcs)
+
+    fsa = k2.Fsa.from_str(arcs, acceptor=False)
+    return fsa
+
+
+def generate_lexicon(
+    model_file: str, words: List[str], oov: str
+) -> Tuple[Lexicon, Dict[str, int]]:
+    """Generate a lexicon from a BPE model.
+
+    Args:
+      model_file:
+        Path to a sentencepiece model.
+      words:
+        A list of strings representing words.
+      oov:
+        The out of vocabulary word in lexicon.
+    Returns:
+      Return a tuple with two elements:
+        - A dict whose keys are words and values are the corresponding
+          word pieces.
+        - A dict representing the token symbol, mapping from tokens to IDs.
+    """
+    sp = spm.SentencePieceProcessor()
+    sp.load(str(model_file))
+
+    # Convert word to word piece IDs instead of word piece strings
+    # to avoid OOV tokens.
+    words_pieces_ids: List[List[int]] = sp.encode(words, out_type=int)
+
+    # Now convert word piece IDs back to word piece strings.
+    words_pieces: List[List[str]] = [sp.id_to_piece(ids) for ids in words_pieces_ids]
+
+    lexicon = []
+    for word, pieces in zip(words, words_pieces):
+        lexicon.append((word, pieces))
+
+    lexicon.append((oov, ["▁", sp.id_to_piece(sp.unk_id())]))
+
+    token2id: Dict[str, int] = {sp.id_to_piece(i): i for i in range(sp.vocab_size())}
+
+    return lexicon, token2id
+
+
+def get_args():
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "--lang-dir",
+        type=str,
+        help="""Input and output directory.
+        It should contain the bpe.model and words.txt
+        """,
+    )
+
+    parser.add_argument(
+        "--oov",
+        type=str,
+        default="<UNK>",
+        help="The out of vocabulary word in lexicon.",
+    )
+
+    parser.add_argument(
+        "--debug",
+        type=str2bool,
+        default=False,
+        help="""True for debugging, which will generate
+        a visualization of the lexicon FST.
+
+        Caution: If your lexicon contains hundreds of thousands
+        of lines, please set it to False!
+
+        See "test/test_bpe_lexicon.py" for usage.
+        """,
+    )
+
+    return parser.parse_args()
+
+
+def main():
+    args = get_args()
+    lang_dir = Path(args.lang_dir)
+    model_file = lang_dir / "bpe.model"
+
+    word_sym_table = k2.SymbolTable.from_file(lang_dir / "words.txt")
+
+    words = word_sym_table.symbols
+
+    excluded = ["<eps>", "!SIL", "<SPOKEN_NOISE>", args.oov, "#0", "<s>", "</s>"]
+
+    for w in excluded:
+        if w in words:
+            words.remove(w)
+
+    lexicon, token_sym_table = generate_lexicon(model_file, words, args.oov)
+
+    lexicon_disambig, max_disambig = add_disambig_symbols(lexicon)
+
+    next_token_id = max(token_sym_table.values()) + 1
+    for i in range(max_disambig + 1):
+        disambig = f"#{i}"
+        assert disambig not in token_sym_table
+        token_sym_table[disambig] = next_token_id
+        next_token_id += 1
+
+    word_sym_table.add("#0")
+    word_sym_table.add("<s>")
+    word_sym_table.add("</s>")
+
+    write_mapping(lang_dir / "tokens.txt", token_sym_table)
+
+    write_lexicon(lang_dir / "lexicon.txt", lexicon)
+    write_lexicon(lang_dir / "lexicon_disambig.txt", lexicon_disambig)
+
+    L = lexicon_to_fst_no_sil(
+        lexicon,
+        token2id=token_sym_table,
+        word2id=word_sym_table,
+    )
+
+    L_disambig = lexicon_to_fst_no_sil(
+        lexicon_disambig,
+        token2id=token_sym_table,
+        word2id=word_sym_table,
+        need_self_loops=True,
+    )
+    torch.save(L.as_dict(), lang_dir / "L.pt")
+    torch.save(L_disambig.as_dict(), lang_dir / "L_disambig.pt")
+
+    if args.debug:
+        labels_sym = k2.SymbolTable.from_file(lang_dir / "tokens.txt")
+        aux_labels_sym = k2.SymbolTable.from_file(lang_dir / "words.txt")
+
+        L.labels_sym = labels_sym
+        L.aux_labels_sym = aux_labels_sym
+        L.draw(f"{lang_dir / 'L.svg'}", title="L.pt")
+
+        L_disambig.labels_sym = labels_sym
+        L_disambig.aux_labels_sym = aux_labels_sym
+        L_disambig.draw(f"{lang_dir / 'L_disambig.svg'}", title="L_disambig.pt")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/egs/ami/SURT/local/train_bpe_model.py b/egs/ami/SURT/local/train_bpe_model.py
new file mode 100755
index 000000000..43142aee4
--- /dev/null
+++ b/egs/ami/SURT/local/train_bpe_model.py
@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+# You can install sentencepiece via:
+#
+#  pip install sentencepiece
+#
+# Due to an issue reported in
+# https://github.com/google/sentencepiece/pull/642#issuecomment-857972030
+#
+# Please install a version >=0.1.96
+
+import argparse
+import shutil
+from pathlib import Path
+
+import sentencepiece as spm
+
+
+def get_args():
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "--lang-dir",
+        type=str,
+        help="""Input and output directory.
+        The generated bpe.model is saved to this directory.
+        """,
+    )
+
+    parser.add_argument(
+        "--transcript",
+        type=str,
+        help="Training transcript.",
+    )
+
+    parser.add_argument(
+        "--vocab-size",
+        type=int,
+        help="Vocabulary size for BPE training",
+    )
+
+    return parser.parse_args()
+
+
+def main():
+    args = get_args()
+    vocab_size = args.vocab_size
+    lang_dir = Path(args.lang_dir)
+
+    model_type = "unigram"
+
+    model_prefix = f"{lang_dir}/{model_type}_{vocab_size}"
+    train_text = args.transcript
+    character_coverage = 1.0
+    input_sentence_size = 100000000
+
+    user_defined_symbols = ["<blk>", "<sos/eos>"]
+    unk_id = len(user_defined_symbols)
+    # Note: unk_id is fixed to 2.
+    # If you change it, you should also change other
+    # places that are using it.
+
+    model_file = Path(model_prefix + ".model")
+    if not model_file.is_file():
+        spm.SentencePieceTrainer.train(
+            input=train_text,
+            vocab_size=vocab_size,
+            model_type=model_type,
+            model_prefix=model_prefix,
+            input_sentence_size=input_sentence_size,
+            character_coverage=character_coverage,
+            user_defined_symbols=user_defined_symbols,
+            unk_id=unk_id,
+            bos_id=-1,
+            eos_id=-1,
+        )
+    else:
+        print(f"{model_file} exists - skipping")
+        return
+
+    shutil.copyfile(model_file, f"{lang_dir}/bpe.model")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/egs/ami/SURT/prepare.sh b/egs/ami/SURT/prepare.sh
new file mode 100755
index 000000000..ea4e5baf2
--- /dev/null
+++ b/egs/ami/SURT/prepare.sh
@@ -0,0 +1,195 @@
+#!/usr/bin/env bash
+
+set -eou pipefail
+
+stage=-1
+stop_stage=100
+
+# We assume dl_dir (download dir) contains the following
+# directories and files. If not, they will be downloaded
+# by this script automatically.
+#
+#  - $dl_dir/ami
+#      You can find audio and transcripts for AMI in this path.
+#
+#  - $dl_dir/icsi
+#      You can find audio and transcripts for ICSI in this path.
+#
+#  - $dl_dir/rirs_noises
+#      This directory contains the RIRS_NOISES corpus downloaded from https://openslr.org/28/.
+#
+dl_dir=$PWD/download
+
+. shared/parse_options.sh || exit 1
+
+# All files generated by this script are saved in "data".
+# You can safely remove "data" and rerun this script to regenerate it.
+mkdir -p data
+vocab_size=500
+
+log() {
+  # This function is from espnet
+  local fname=${BASH_SOURCE[1]##*/}
+  echo -e "$(date '+%Y-%m-%d %H:%M:%S') (${fname}:${BASH_LINENO[0]}:${FUNCNAME[1]}) $*"
+}
+
+log "dl_dir: $dl_dir"
+
+if [ $stage -le 0 ] && [ $stop_stage -ge 0 ]; then
+  log "Stage 0: Download data"
+
+  # If you have pre-downloaded it to /path/to/amicorpus,
+  # you can create a symlink
+  #
+  #   ln -sfv /path/to/amicorpus $dl_dir/amicorpus
+  #
+  if [ ! -d $dl_dir/amicorpus ]; then
+    for mic in ihm ihm-mix sdm mdm8-bf; do
+      lhotse download ami --mic $mic $dl_dir/amicorpus
+    done
+  fi
+
+  # If you have pre-downloaded it to /path/to/icsi,
+  # you can create a symlink
+  #
+  #   ln -sfv /path/to/icsi $dl_dir/icsi
+  #
+  if [ ! -d $dl_dir/icsi ]; then
+    lhotse download icsi $dl_dir/icsi
+  fi
+
+  # If you have pre-downloaded it to /path/to/rirs_noises,
+  # you can create a symlink
+  #
+  #   ln -sfv /path/to/rirs_noises $dl_dir/
+  #
+  if [ ! -d $dl_dir/rirs_noises ]; then
+    lhotse download rirs_noises $dl_dir
+  fi
+fi
+
+if [ $stage -le 1 ] && [ $stop_stage -ge 1 ]; then
+  log "Stage 1: Prepare AMI manifests"
+  # We assume that you have downloaded the AMI corpus
+  # to $dl_dir/amicorpus. We perform text normalization for the transcripts.
+  mkdir -p data/manifests
+  for mic in ihm ihm-mix sdm mdm8-bf; do
+    log "Preparing AMI manifest for $mic"
+    lhotse prepare ami --mic $mic --max-words-per-segment 30 --merge-consecutive $dl_dir/amicorpus data/manifests/
+  done
+fi
+
+if [ $stage -le 2 ] && [ $stop_stage -ge 2 ]; then
+  log "Stage 2: Prepare ICSI manifests"
+  # We assume that you have downloaded the ICSI corpus
+  # to $dl_dir/icsi. We perform text normalization for the transcripts.
+  mkdir -p data/manifests
+  log "Preparing ICSI manifest"
+  for mic in ihm ihm-mix sdm; do
+    lhotse prepare icsi --mic $mic $dl_dir/icsi data/manifests/
+  done
+fi
+
+if [ $stage -le 3 ] && [ $stop_stage -ge 3 ]; then
+  log "Stage 3: Prepare RIRs"
+  # We assume that you have downloaded the RIRS_NOISES corpus
+  # to $dl_dir/rirs_noises
+  lhotse prepare rir-noise -p real_rir -p iso_noise $dl_dir/rirs_noises data/manifests
+fi
+
+if [ $stage -le 4 ] && [ $stop_stage -ge 4 ]; then
+  log "Stage 3: Extract features for AMI and ICSI recordings"
+  python local/compute_fbank_ami.py
+  python local/compute_fbank_icsi.py
+fi
+
+if [ $stage -le 5 ] && [ $stop_stage -ge 5 ]; then
+  log "Stage 5: Create sources for simulating mixtures"
+  # In the following script, we speed-perturb the IHM recordings and extract features.
+  python local/compute_fbank_ihm.py
+  lhotse combine data/manifests/ami-ihm_cuts_train.jsonl.gz \
+    data/manifests/icsi-ihm_cuts_train.jsonl.gz - |\
+    lhotse cut trim-to-alignments --type word --max-pause 0.5 - - |\
+    lhotse filter 'duration<=12.0' - - |\
+    shuf | gzip -c > data/manifests/ihm_cuts_train_trimmed.jsonl.gz
+fi
+
+if [ $stage -le 6 ] && [ $stop_stage -ge 6 ]; then
+  log "Stage 6: Create training mixtures"
+  lhotse workflows simulate-meetings \
+    --method conversational \
+    --same-spk-pause 0.5 \
+    --diff-spk-pause 0.5 \
+    --diff-spk-overlap 1.0 \
+    --prob-diff-spk-overlap 0.8 \
+    --num-meetings 200000 \
+    --num-speakers-per-meeting 2,3 \
+    --max-duration-per-speaker 15.0 \
+    --max-utterances-per-speaker 3 \
+    --seed 1234 \
+    --num-jobs 2 \
+    data/manifests/ihm_cuts_train_trimmed.jsonl.gz \
+    data/manifests/ai-mix_cuts_clean.jsonl.gz
+
+  python local/compute_fbank_aimix.py
+
+  # Add source features to the manifest (will be used for masking loss)
+  # This may take ~2 hours.
+  python local/add_source_feats.py
+
+  # Combine clean and reverb
+  cat <(gunzip -c data/manifests/cuts_train_clean_sources.jsonl.gz) \
+    <(gunzip -c data/manifests/cuts_train_reverb_sources.jsonl.gz) |\
+    shuf | gzip -c > data/manifests/cuts_train_comb_sources.jsonl.gz
+fi
+
+if [ $stage -le 7 ] && [ $stop_stage -ge 7 ]; then
+  log "Stage 7: Create training mixtures from real sessions"
+  python local/prepare_ami_train_cuts.py
+  python local/prepare_icsi_train_cuts.py
+
+  # Combine AMI and ICSI
+  cat <(gunzip -c data/manifests/cuts_train_ami.jsonl.gz) \
+    <(gunzip -c data/manifests/cuts_train_icsi.jsonl.gz) |\
+    shuf | gzip -c > data/manifests/cuts_train_ami_icsi.jsonl.gz
+fi
+
+if [ $stage -le 8 ] && [ $stop_stage -ge 8 ]; then
+  log "Stage 8: Dump transcripts for BPE model training (using AMI and ICSI)."
+  mkdir -p data/lm
+  cat <(gunzip -c data/manifests/ami-sdm_supervisions_train.jsonl.gz | jq '.text' | sed 's:"::g') \
+      <(gunzip -c data/manifests/icsi-sdm_supervisions_train.jsonl.gz | jq '.text' | sed 's:"::g') \
+  > data/lm/transcript_words.txt
+fi
+
+if [ $stage -le 9 ] && [ $stop_stage -ge 9 ]; then
+  log "Stage 9: Prepare BPE based lang (combining AMI and ICSI)"
+
+  lang_dir=data/lang_bpe_${vocab_size}
+  mkdir -p $lang_dir
+
+  # Add special words to words.txt
+  echo "<eps> 0" > $lang_dir/words.txt
+  echo "!SIL 1" >> $lang_dir/words.txt
+  echo "<UNK> 2" >> $lang_dir/words.txt
+
+  # Add regular words to words.txt
+  cat data/lm/transcript_words.txt | grep -o -E '\w+' | sort -u | awk '{print $0,NR+2}' >> $lang_dir/words.txt
+
+  # Add remaining special word symbols expected by LM scripts.
+  num_words=$(cat $lang_dir/words.txt | wc -l)
+  echo "<s> ${num_words}" >> $lang_dir/words.txt
+  num_words=$(cat $lang_dir/words.txt | wc -l)
+  echo "</s> ${num_words}" >> $lang_dir/words.txt
+  num_words=$(cat $lang_dir/words.txt | wc -l)
+  echo "#0 ${num_words}" >> $lang_dir/words.txt
+
+  ./local/train_bpe_model.py \
+    --lang-dir $lang_dir \
+    --vocab-size $vocab_size \
+    --transcript data/lm/transcript_words.txt
+
+  if [ ! -f $lang_dir/L_disambig.pt ]; then
+    ./local/prepare_lang_bpe.py --lang-dir $lang_dir
+  fi
+fi
diff --git a/egs/ami/SURT/shared b/egs/ami/SURT/shared
new file mode 120000
index 000000000..4cbd91a7e
--- /dev/null
+++ b/egs/ami/SURT/shared
@@ -0,0 +1 @@
+../../../icefall/shared
\ No newline at end of file