diff --git a/egs/himia/wuw/ctc_tdnn/decode.py b/egs/himia/wuw/ctc_tdnn/decode.py
new file mode 100755
index 000000000..7acc7d595
--- /dev/null
+++ b/egs/himia/wuw/ctc_tdnn/decode.py
@@ -0,0 +1,279 @@
+#!/usr/bin/env python3
+# Copyright    2023  Xiaomi Corp.        (Author: Weiji Zhuang,
+#                                                 Liyong Guo)
+#
+# 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.
+
+import argparse
+import copy
+import logging
+from concurrent.futures import ProcessPoolExecutor
+from typing import Tuple
+
+import numpy as np
+from lhotse.features.io import NumpyHdf5Reader
+from tqdm import tqdm
+
+from icefall.utils import AttributeDict
+
+from train import get_params
+from graph import ctc_trivial_decoding_graph
+
+
+class Arc:
+    def __init__(
+        self, src_state: int, dst_state: int, ilabel: int, olabel: int
+    ) -> None:
+        self.src_state = int(src_state)
+        self.dst_state = int(dst_state)
+        self.ilabel = int(ilabel)
+        self.olabel = int(olabel)
+
+    def next_state(self) -> None:
+        return self.dst_state
+
+
+class State:
+    def __init__(self) -> None:
+        self.arc_list = list()
+
+    def add_arc(self, arc: Arc) -> None:
+        self.arc_list.append(arc)
+
+
+class FiniteStateTransducer:
+    """Represents a decoding graph for wake word detection."""
+
+    def __init__(self, graph: str) -> None:
+        self.state_list = list()
+        for arc_str in graph.split("\n"):
+            arc = arc_str.strip().split()
+            if len(arc) == 0:
+                continue
+            # 1 and 2 for final state
+            # 4 for non-final state
+            assert len(arc) in [1, 2, 4], f"{len(arc)} {arc_str}"
+            if len(arc) == 4:  # Non-final state
+                # FST must be sorted
+                if len(self.state_list) <= int(arc[0]):
+                    new_state = State()
+                    self.state_list.append(new_state)
+                self.state_list[int(arc[0])].add_arc(
+                    Arc(arc[0], arc[1], arc[2], arc[3])
+                )
+            else:
+                self.final_state_id = int(arc[0])
+
+    def to_str(self) -> None:
+        fst_str = ""
+        for state_idx in range(len(self.state_list)):
+            cur_state = self.state_list[state_idx]
+            for arc_idx in range(len(cur_state.arc_list)):
+                cur_arc = cur_state.arc_list[arc_idx]
+                ilabel = cur_arc.ilabel
+                olabel = cur_arc.olabel
+                src_state = cur_arc.src_state
+                dst_state = cur_arc.dst_state
+                fst_str += f"{src_state} {dst_state} {ilabel} {olabel}\n"
+        fst_str += f"{dst_state}\n"
+        return fst_str
+
+
+class Token:
+    def __init__(self) -> None:
+        self.is_active = False
+        self.total_score = -float("inf")
+        self.keyword_frames = 0
+        self.average_keyword_score = -float("inf")
+        self.average_max_keyword_score = 0.0
+
+    def set_token(
+        self,
+        src_token,
+        is_keyword_ilabel: bool,
+        acoustic_score: float,
+    ) -> None:
+        """
+        A dynamic programming process computing the highest score for a token
+        from all possible paths which could reach this token.
+
+        Args:
+          src_token: The source token connected to current token with an arc.
+          is_keyword_ilabel: If true, the arc consumes an input label which is
+            a part of wake word. Otherwhise, the input label is
+            blank or unknown, i.e. current token is still not part of wake word.
+          acoustic_score: acoustic score of this arc.
+        """
+
+        if (
+            not self.is_active
+            or self.total_score < src_token.total_score + acoustic_score
+        ):
+            self.is_active = True
+            self.total_score = src_token.total_score + acoustic_score
+
+            if is_keyword_ilabel:
+                self.average_keyword_score = (
+                    acoustic_score
+                    + src_token.average_keyword_score * src_token.keyword_frames
+                ) / (src_token.keyword_frames + 1)
+
+                self.keyword_frames = src_token.keyword_frames + 1
+            else:
+                self.average_keyword_score = 0.0
+
+
+class SingleDecodable:
+    def __init__(
+        self,
+        model_output,
+        keyword_ilabel_start,
+        graph,
+    ):
+        """
+        Args:
+          model_output: log_softmax(logit) with shape [T, C]
+          keyword_ilabel_start: index of the first token of the wake word.
+            In this recipe, tokens not for wake word has smaller token index,
+            i.e. blank 0; unk 1.
+          graph: decoding graph of the wake word.
+
+        """
+        self.init_token_list = [Token() for i in range(len(graph.state_list))]
+        self.reset_token_list()
+        self.model_output = model_output
+        self.T = model_output.shape[0]
+        self.utt_score = 0.0
+        self.current_frame_index = 0
+        self.keyword_ilabel_start = keyword_ilabel_start
+        self.graph = graph
+        self.number_tokens = len(self.cur_token_list)
+
+    def reset_token_list(self) -> None:
+        """
+        Reset all tokens to a condition without consuming any acoustic frames.
+        """
+        self.cur_token_list = copy.deepcopy(self.init_token_list)
+        self.expand_token_list = copy.deepcopy(self.init_token_list)
+        self.cur_token_list[0].is_active = True
+        self.cur_token_list[0].total_score = 0
+        self.cur_token_list[0].average_keyword_score = 0
+
+    def process_oneframe(self) -> None:
+        """
+        Decode a frame and update all tokens.
+        """
+        for state_id, cur_token in enumerate(self.cur_token_list):
+            if cur_token.is_active:
+                for arc_id in self.graph.state_list[state_id].arc_list:
+                    acoustic_score = self.model_output[self.current_frame_index][
+                        arc_id.ilabel
+                    ]
+                    is_keyword_ilabel = arc_id.ilabel >= self.keyword_ilabel_start
+                    self.expand_token_list[arc_id.next_state()].set_token(
+                        cur_token,
+                        is_keyword_ilabel,
+                        acoustic_score,
+                    )
+        # use best_score to keep total_score in a good range
+        self.best_state_id = 0
+        best_score = self.expand_token_list[0].total_score
+        for state_id in range(self.number_tokens):
+            if self.expand_token_list[state_id].is_active:
+                if best_score < self.expand_token_list[state_id].total_score:
+                    best_score = self.expand_token_list[state_id].total_score
+                    self.best_state_id = state_id
+
+        self.cur_token_list = self.expand_token_list
+        for state_id in range(self.number_tokens):
+            self.cur_token_list[state_id].total_score -= best_score
+        self.expand_token_list = copy.deepcopy(self.init_token_list)
+        potential_score = np.exp(
+            self.cur_token_list[self.graph.final_state_id].average_keyword_score
+        )
+        if potential_score > self.utt_score:
+            self.utt_score = potential_score
+        self.current_frame_index += 1
+
+
+def decode_utt(
+    params: AttributeDict, utt_id: str, post_file, graph: FiniteStateTransducer
+) -> Tuple[str, float]:
+    """
+    Decode a single utterance.
+
+    Args:
+      params:
+        The return value of :func:`get_params`.
+      utt_id: utt_id to be decoded, used to fetch posterior matrix from post_file.
+      post_file: file to save posterior for all test set.
+      graph: decoding graph.
+
+    Returns:
+      utt_id and its corresponding probability to be a wake word.
+    """
+    reader = NumpyHdf5Reader(post_file)
+    model_output = reader.read(utt_id)
+    keyword_ilabel_start = params.wakeup_word_tokens[0]
+    decodable = SingleDecodable(
+        model_output=model_output,
+        keyword_ilabel_start=keyword_ilabel_start,
+        graph=graph,
+    )
+    for t in range(decodable.T):
+        decodable.process_oneframe()
+    return utt_id, decodable.utt_score
+
+
+def get_parser():
+    parser = argparse.ArgumentParser(
+        description="A simple FST decoder for the wake word detection\n"
+    )
+    parser.add_argument(
+        "--decoding-graph", help="decoding graph", default="himia_ctc_graph.txt"
+    )
+    parser.add_argument("--post-h5", help="model output in h5 format")
+    parser.add_argument("--score-file", help="file to save scores of each utterance")
+    return parser
+
+
+def main():
+    logging.basicConfig(
+        level=logging.INFO, format="%(asctime)s %(levelname)s %(message)s"
+    )
+    parser = get_parser()
+    args = parser.parse_args()
+    params = get_params()
+    params.update(vars(args))
+
+    keys = NumpyHdf5Reader(params.post_h5).hdf.keys()
+    graph = FiniteStateTransducer(ctc_trivial_decoding_graph(params.wakeup_word_tokens))
+    logging.info(f"Graph used:\n{graph.to_str()}")
+    logging.info("About to load data to decoder.")
+    with ProcessPoolExecutor() as executor, open(
+        params.score_file, "w", encoding="utf8"
+    ) as fout:
+        futures = [
+            executor.submit(decode_utt, params, key, params.post_h5, graph)
+            for key in tqdm(keys)
+        ]
+        logging.info("Decoding.")
+        for future in tqdm(futures):
+            k, v = future.result()
+            fout.write(str(k) + " " + str(v) + "\n")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/egs/himia/wuw/local/auc.py b/egs/himia/wuw/local/auc.py
new file mode 100755
index 000000000..d7357a0f1
--- /dev/null
+++ b/egs/himia/wuw/local/auc.py
@@ -0,0 +1,115 @@
+#!/usr/bin/env python3
+# Copyright    2023  Xiaomi Corp.        (Author: Weiji Zhuang,
+#                                                 Liyong Guo)
+#
+# 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.
+
+import argparse
+import logging
+from typing import Dict, Tuple
+
+import matplotlib.pyplot as plt
+import numpy as np
+from pathlib import Path
+from sklearn.metrics import roc_curve, auc
+
+
+def get_args():
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "--positive-score-file", required=True, help="score file of positive data"
+    )
+    parser.add_argument(
+        "--negative-score-file", required=True, help="score file of negative data"
+    )
+    parser.add_argument("--legend", required=True, help="utt2dur file of negative data")
+    return parser.parse_args()
+
+
+def load_score(score_file: Path) -> Dict[str, float]:
+    """
+    Args:
+      score_file: Path to score file. Each line has two columns.
+        The first colume is utt-id, and the second one is score.
+        This score could be viewed as probability of being wakeup word.
+
+    Returns:
+      A dict with that key is utt-id and value is corresponding score.
+    """
+    pos_dict = {}
+    with open(score_file, "r", encoding="utf8") as fin:
+        for line in fin:
+            arr = line.strip().split()
+            assert len(arr) == 2
+            key = arr[0]
+            score = float(arr[1])
+            pos_dict[key] = score
+    return pos_dict
+
+
+def get_roc_and_auc(
+    pos_dict: Dict,
+    neg_dict: Dict,
+) -> Tuple[np.array, np.array, float]:
+    """
+    Args:
+      pos_dict: scores of positive samples.
+      neg_dict: scores of negative samples.
+    Return:
+      A tuple of three elements, which will be used to plot roc curve.
+      Refer to sklearn.metrics.roc_curve for meaning of the first and second elements.
+      The third element is area under the roc curve(AUC).
+    """
+    pos_scores = np.fromiter(pos_dict.values(), dtype=float)
+    neg_scores = np.fromiter(neg_dict.values(), dtype=float)
+
+    pos_y = np.ones_like(pos_scores, dtype=int)
+    neg_y = np.zeros_like(neg_scores, dtype=int)
+
+    scores = np.concatenate([pos_scores, neg_scores])
+    y = np.concatenate([pos_y, neg_y])
+
+    fpr, tpr, thresholds = roc_curve(y, scores, pos_label=1)
+    roc_auc = auc(fpr, tpr)
+
+    return fpr, tpr, roc_auc
+
+
+def main():
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+
+    args = get_args()
+    logging.basicConfig(format=formatter, level=logging.INFO)
+    pos_dict = load_score(args.positive_score_file)
+    neg_dict = load_score(args.negative_score_file)
+    fpr, tpr, roc_auc = get_roc_and_auc(pos_dict, neg_dict)
+
+    plt.figure(figsize=(16, 9))
+    plt.plot(fpr, tpr, label=f"{args.legend}(AUC = %1.8f)" % roc_auc)
+
+    plt.xlim([0.0, 1.0])
+    plt.ylim([0.0, 1.0])
+    plt.xlabel("False Positive Rate")
+    plt.ylabel("True Positive Rate")
+    plt.title("Receiver operating characteristic(ROC)")
+    plt.legend(loc="lower right")
+
+    output_path = Path(args.positive_score_file).parent
+    logging.info(f"AUC of {args.legend} {output_path}: {roc_auc}")
+    plt.savefig(f"{output_path}/{args.legend}.pdf", bbox_inches="tight")
+
+
+if __name__ == "__main__":
+    main()