Voice Search アプリは Android 上での音声入力による Web 検索を可能にしました。さらに、このアプリが提供しているシンプルな API を利用することで、アプリ開発者は自分の Android アプリに、この音声認識機能を組み込むことができます。このセッションでは、音声認識技術の詳細を簡単にご紹介し、実際に Voice Search API を利用したアプリのデモ、コードの解説を行ないます。

2. Revised v4Presenter
Speech Input API For Android
Alex Gruenstein

3. Outline
• Android built-in speech features
• Speech recognition primer
• How to: integrate speech input directly in your
Android application

4. Voice Search
• Speak any Google search query
• Supported on Android, iPhone/
iPod/iPad, Blackberry, Nokia s60
• 15 Languages:
• English (US, UK, Indian,
Australian), Japanese,
Mandarin, Korean, Taiwanese,
French, Italian, German,
Spanish, Russian, Polish,
Czech
• Video

5. Voice Actions
• Beyond search
• Send text to Clare Homberlyn
Hey are you coming home?
• Send e-mail I’m running late.
• Navigate to the Museum of
Modern Art
• Listen to The Beatles
• Go to Wikipedia
• Video

6. Android Voice Input
• Speak anywhere
you would
normally type.
• Status updates,
Twitter, SMS,
Email, etc.
• Video

7. Revised v4Presenter
Speech Recognition

8. Google’s Speech Recognizer
Google speech server
US English
Acoustic
Model
Dictionary
Search
Language
Model
Dictation
Language
Model
Japanese
Acoustic
Model
Dictionary
Search
Language
Model
Dictation
Language
Model
…

9. Layered Stochastic Models
Audio -> phonetic units
• P(t1 -> “eh”) = .7
• P(t1 -> “iy”) = .3
Words -> phonetic units
• P(read -> r eh d) = .6
• P(read -> r iy d) = .4
Probability of word sequences
• P(“read a book”) > P(“read a flower”)
Acoustic
Model
Dictionary
Language
Model
t0
t1
…

10. Estimated with Data
• The language model is estimated using logs
of billions of Google searches.Language
Model

11. Estimated with Data
• The language model is estimated using logs
of billions of Google searches.
• Counts of short sequences of words are
used to estimate the probability of any
sentence
• “san francisco golden gate bridge” ->
• “san francisco golden”
• “francisco golden gate”
• “golden gate bridge”
• Counting and probability smoothing
requires many hours on thousands of
computers!
Language
Model

12. Revised v4Presenter
How to:
Integrate speech input directly in
your Android application

13. Android Speech Input API
• Android’s open platform makes it simple to
access Google’s speech recognizer
programmatically from your application.
• (Or any recognizer that registers for
RecognizerIntent)
• Simple to use to the API to:
• Prompt the user to start speaking,
• Stream the audio Google’s servers,
• Retrieve the recognition hypothesis.

14. Example code
// Called when someone clicks a button in your app
public void onClick(View button) {
// Create a recognition request
Intent intent = new
Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
// Set the language model
intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
// Send the request to display prompt, record audio, and return a result
startActivityForResult(intent, 0);
}
// Called when speech recognition is finished
protected void onActivityResult(int requestCode,
int resultCode,
Intent intent) {
// Get the n-best list
ArrayList<String> nbest =
intent.getStringArrayListExtra(
RecognizerIntent.EXTRA_RESULTS);
// Do something with best result, e.g. “golden gate bridge”
DoSomething(nbest.get(0))
}

15. Parameters
• Language (EXTRA_LANGUAGE), e.g.
• ja_jp (Japanese)
• en_us (US English)
• If not set, then the phone’s default language is
used.
• Language Model hints
(EXTRA_LANGUAGE_MODEL)
• Search – Good for short queries, business
names, cities. The types of things people
search for on Google.
• Free form – For dictation. Sending e-mail,
SMS, etc.

16. Google Speech Technology
• More than just mobile phones…
• Automatic subtitles for YouTube videos
• Voicemail transcription for Google Voice
• 1-800-GOOG-411: free telephone directory
assistance

17. What’s next?
• Video
• http://www.google.co.jp/intl/ja/landing/animaru/