李宏毅/當語音處理遇上深度學習

1. Deep Learning and its Applica1on on Speech Processing Hung-yi Lee

2. Spoken Content Speech Recogni4on Recogni4on Output Speech Recogni,on How to do speech recogni4on with deep learning? Deep Learning

3. People imagine …… This is not true! DNN can only take ﬁxed-length vectors as input and output. “大家好我今天 ….” DNN Input and output are sequences with diﬀerent lengths.

4. Recurrent Neural Network x1 x2 x3 y1 y2 y3 Wi Wo …… Wh Wh Wi Wo Wi Wo How about Recurrent Neural Network (RNN)?

5. Recurrent Neural Network 好好好 Trimming 棒棒棒棒棒 “好棒” Why can’t it be “好棒棒” Input: Output: (character sequence) (vector sequence ) Problem? How about Recurrent Neural Network (RNN)? 0.01s

6. Recurrent Neural Network •  Connec4onist Temporal Classiﬁca4on (CTC) [Alex Graves, ICML’06][Alex Graves, ICML’14][Haşim Sak, Interspeech’15][Jie Li, Interspeech’15][Andrew Senior, ASRU’15] 好 φ φ 棒 φ φ φ φ 好 φ φ 棒 φ 棒 φ φ “好棒” “好棒棒” Add an extra symbol “φ” represen4ng “null”

7. Sequence-to-sequence Learning •  Sequence to sequence learning: Both input and output are both sequences with diﬀerent lengths. Containing all informa4on about input uferance …… …… “機器學習” acous4c feature sequence → character sequence

8. Sequence-to-sequence Learning •  Sequence to sequence learning: Both input and output are both sequences with diﬀerent lengths. …… …… “機器學習” 機習器學 …… …… 慣性 Don’t know when to stop

9. Sequence-to-sequence Learning •  Sequence to sequence learning: Both input and output are both sequences with diﬀerent lengths. …… …… “機器學習” 機習器學 Add a symbol “。 “ (句點) [Ilya Sutskever, NIPS’14][Dzmitry Bahdanau, arXiv’15] 。

10. Spoken Content Speech Recogni4on Recogni4on Output Retrieval Retrieval Result Spoken Content Retrieval

11. People think …… l Transcribe spoken content into text by speech recognition Speech Recognition Models Text Retrieval Result Text Retrieval Query learner l Use text retrieval approach to search the transcriptions Spoken Content Black Box

12. People think …… Spoken Content Retrieval Speech Recognition + Text Retrieval =

13. •  Good spoken content retrieval needs good speech recognition system. •  In real application, such high quality recognition models are not available •  Ex, YouTube •  Different languages/accents •  Different recording environments •  Hope for spoken content retrieval •  Don’t completely rely on accurate speech recognition •  Accurate spoken content retrieval, even under poor speech recognition Problem?

14. Spoken Content Speech Recogni4on Beyond Cascading ? Recogni4on Output Retrieval Retrieval Result Spoken Content Retrieval ¨  Is the cascading of speech recognition and text retrieval the only solution of spoken content retrieval?

15. Beyond Cascading Speech Recogni1on and Text Retrieval •  5 direc4ons •  Modiﬁed Speech Recogni4on for Retrieval Purposes •  Exploi4ng Informa4on not present in ASR outputs •  Directly Matching on Acous4c Level without ASR •  Seman4c Retrieval of Spoken Content •  Interac4ve Retrieval and Eﬃcient Presenta4on of Retrieved Objects Overview paper "Spoken Content Retrieval —Beyond Cascading Speech Recogni4on with Text Retrieval" http://speech.ee.ntu.edu.tw/~tlkagk/paper/Overview.pdf

16. Our Point Spoken Content Retrieval Speech Recognition + Text Retrieval =

17. Spoken Content Speech Recogni4on Beyond Cascading ? Recogni4on Output Retrieval Retrieval Result Interac4on user Interact with Humans

18. Spoken Content Speech Recogni4on Beyond Cascading ? Recogni4on Output Retrieval Seman4c Analysis Retrieval Result Interac4on user Seman,c Analysis

19. Unsupervised Learning •  Machine reads lots of text on the Internet …… 蔡英文 520宣誓就職馬英九 520宣誓就職蔡英文、馬英九 are something very similar You shall know a word by the company it keeps

20. Seman1c Analysis •  Let machine read lots of documents. •  Each word is represented as a vector dog cat rabbit jump run ﬂower tree

21. Seman1c Analysis •  Even the distances between the vectors have some meaning. Source: hfp:// www.slideshare.net/hustwj/cikm- keynotenov2014

22. Spoken Content Speech Recogni4on Beyond Cascading ? Recogni4on Output Retrieval Seman4c Analysis Key Term Extrac4on Retrieval Result Interac4on user Key Term Extrac,on [Interspeech 2015] (with 沈昇勳)

23. Spoken Content Speech Recogni4on Beyond Cascading ? Recogni4on Output Retrieval Seman4c Analysis Key Term Extrac4on Retrieval Result Interac4on user Summariza,on Summari- za4on

24. Speech Summariza1on Retrieved Audio File Summary Select the most informative segments to form a compact version 1 hour long 10 minutes Extrac've Summaries Ref: http://speech.ee.ntu.edu.tw/ ~tlkagk/courses/MLDS_2015/ Structured%20Lecture/Summarization %20Hidden_2.ecm.mp4/index.html

25. Speech Summariza1on •  用自己的話寫 summary (Abstrac4ve Summaries) •  Machine learns to do abstrac4ve summariza4on from 2,000,000 training examples , , , , , ; …… Human Machine 台大電機系盧柏儒、徐翊祥台大資工系葉正杰、周儒杰 (助教:余朗祺)

26. Spoken Content Speech Recogni4on Beyond Cascading ? Recogni4on Output Retrieval Seman4c Analysis Key Term Extrac4on Summari- za4on Ques4on- answering Retrieval Result Interac4on user question answer Ques,on Answering

27. Spoken Content Speech Recogni4on Beyond Cascading ? Recogni4on Output Retrieval Seman4c Analysis Key Term Extrac4on Summari- za4on Ques4on- answering Retrieval Result Interac4on user question answer Without Speech Recogni,on?

28. Outline Very Brief Introduc4on of Deep Learning Towards Machine Comprehension of Spoken Content •  Overview •  Example I: Speech Ques4on Answering •  Example II: Interac4ve Spoken Content Retrieval •  Example III: What can machine learn from audio without any supervision

29. Speech Ques1on Answering •  Machine answers ques4ons based on the informa4on in spoken content What is a possible origin of Venus’ clouds? ……… answer

30. Speech Ques1on Answering •  TOEFL Listening Comprehension Test by Machine •  Example: Ques4on: “ What is a possible origin of Venus’ clouds? ” Audio Story: Choices: (A) gases released as a result of volcanic activity (B) chemical reactions caused by high surface temperatures (C) bursts of radio energy from the plane's surface (D) strong winds that blow dust into the atmosphere (The original story is 5 min long.)

31. Simple Baselines Accuracy (%) (1) (2) (3) (4) (5) (6) (7) Naive Approaches random (4) 選 seman4c 和其他選項最像的選項 (2) select the shortest choice as answer Experimental setup: 717 for training, 124 for validation, 122 for testing

32. Supervised Learning Accuracy (%) (1) (2) (3) (4) (5) (6) (7) Memory Network: 39.2% Naive Approaches Interspeech 2016 (with 曾柏翔) (proposed by FB AI group)

33. Model Architecture “what is a possible origin of Venus Ques4on: Ques4on Seman4cs …… It be quite possible that this be due to volcanic erup4on because volcanic erup4on o{en emit gas. If that be the case volcanism could very well be the root cause of Venus 's thick cloud cover. And also we have observe burst of radio energy from the planet 's surface. These burst be similar to what we see when volcano erupt on earth …… Audio Story: Speech Recogni4on Seman4c Analysis Seman4c Analysis Afen4on (畫重點) Answer Select the choice most similar to the answer Afen4on Similar to Memory Network

34. Model Architecture Word-based Afen4on

35. Model Architecture Sentence-based Afen4on

36. (A) (A) (A) (A) (A) (B) (B) (B)

37. Supervised Learning Accuracy (%) (1) (2) (3) (4) (5) (6) (7) Memory Network: 39.2% Naive Approaches Word-based Afen4on: 48.3% Interspeech 2016 (with 曾柏翔) (proposed by FB AI group)

39. Interact with Users •  Interac4ve retrieval is helpful. user “深度學習” 和機器學習有關的 ”深度學習” 嗎? 還是和教育有關的 ”深度學習” 呢?

40. Audio is hard to browse •  When the system returns the retrieval results, user doesn’t know what he/she get at the ﬁrst glance Retrieval Result

41. user Spoken Content Retrieval Results Spoken Content Interac,ve retrieval of spoken content query Directly showing the retrieval results is probably not a good idea.

42. user Spoken Content Retrieval Results Spoken Content Interac,ve retrieval of spoken content query “Give me an example.” “Is it relevant to XXX?” “Can you give me another query?” “Show the results.” Given the current situation, which action should be taken? ……

43. user Spoken Content Retrieval Results Spoken Content Interac,ve retrieval of spoken content query State Es4ma4on Ac4on Decision state The degree of clarity from the retrieval results ac4on features ¤  The policy π(s) is a function ¤  Input: state s, output: action a Decide the actions by intrinsic policy π(S) [Interspeech 2012][ICASSP 2013]

44. user Spoken Content Retrieval Results Spoken Content Interac,ve retrieval of spoken content query features … …… DNN State EstimationAction Decision Is it relevant to XXX? Give me an example. Show the results. Max

45. user Spoken Content Retrieval Results Spoken Content Interac,ve retrieval of spoken content query features … …… DNN Is it relevant to XXX? Give me an example. Show the results. Max Learned from historical interac4on Goal: maximizing return (Retrieval Quality - User labor)

46. Deep Reinforcement Learning

47. Experimental Results •  Broadcast news, seman4c retrieval Retrieval Quality (MAP) Op4miza4on Target: Retrieval Quality - User labor Hand-cra{ed Deep Learning Previous Method (state + decision) submifed to Interspeech 2016 (with 吳彥諶、林子翔)

48. Experimental Results

50. Unsupervised Learning Machine listens to lots of audio book (TA: ) Audio Word2Vec: Unsupervised Learning of Audio Segment Representa'ons using Sequence-to-sequence Autoencoder (accepted by Interspeech 2016)

51. Audio Word to Vector •  Consider audio segment corresponding to an unknown word Deep Learning with (助教:沈家豪)

52. Audio Word to Vector •  The audio segments corresponding to words with similar pronuncia4ons are close to each other. Deep Learning

53. Audio Word to Vector •  The audio segments corresponding to words with similar pronuncia4ons are close to each other. ever ever never never never dog dog dogs Deep Learning

54. Sequence Auto-encoder

55. How to evaluate never ever Cosine Similarity Phoneme sequence edit distance Deep Learning Deep Learning

56. Experimental Results More similar pronuncia4on Larger cosine similarity.

57. Interes1ng Observa1on •  Projec4ng the embedding vectors to 2-D day days says say

58. Spoken Content Retrieval without Speech Recognition user “US President” spoken query [Hazen, ASRU 09] [Zhang Glass, ASRU 09] [Chan Lee, Interspeech 10] [Zhang Glass, ICASSP 11] [Gupta, Interspeech 11] [Zhang Glass, Interspeech 11] [Zhang Glass, ASRU 09] [Huijbregts, ICASSP 11] [Chan Lee, Interspeech 11] Computing similarity between spoken queries and audio files on signal level Spoken Content Handheld device

59. Spoken Content Retrieval without Speech Recognition • Why spoken content retrieval without speech recognition? •  Lots of audio files in different languages on the Internet •  Most languages have little annotated data for training speech recognition systems. •  Some audio files are produced in several different of languages •  Some languages even do not have text

60. Spoken Content Retrieval without Speech Recognition

61. Retrieval Performance

62. Concluding Remarks Very Brief Introduc4on of Deep Learning Towards Machine Comprehension of Spoken Content •  Overview •  Example I: Speech Ques4on Answering •  Example II: Interac4ve Spoken Content Retrieval •  Example III: What can machine learn from audio without any supervision

63. Thank You for Your Attention