Enable word-level confidence

You can specify that Speech-to-Text indicate a value of accuracy, or confidence level , for individual words in a transcription.

Word-level confidence

When the Speech-to-Text transcribes an audio clip, it also measures the degree of accuracy for the response. The response sent from Speech-to-Text states the confidence level for the entire transcription request as a number between 0.0 and 1.0. The following code sample shows an example of the confidence level value returned by Speech-to-Text.

{
  "results": [
    {
      "alternatives": [
        {
          "transcript": "how old is the Brooklyn Bridge", "confidence": 0.96748614}
      ]
    }
  ]
}

In addition to the confidence level of the entire transcription, Speech-to-Text can also provide the confidence level of individual words within the transcription. The response then includes WordInfo details in the transcription, indicating the confidence level for individual words as shown in the following example.

{
  "results": [
    {
      "alternatives": [
        {
          "transcript": "how old is the Brooklyn Bridge",
          "confidence": 0.98360395,
          "words": [
            {
              "startTime": "0s",
              "endTime": "0.300s",
              "word": "how", "confidence": SOME NUMBER},
            ...
          ]
        }
      ]
    }
  ]
}

Enable word-level confidence in a request

The following code snippet demonstrates how to enable word-level confidence in a transcription request to Speech-to-Text using local and remote files

Use a local file

Protocol

Refer to the speech:recognize API endpoint for complete details.

To perform synchronous speech recognition, make a POST request and provide the appropriate request body. The following shows an example of a POST request using curl . The example uses the Google Cloud CLI to generate an access token. For instructions on installing the gcloud CLI, see the quickstart .

The following example show how to send a POST request using curl , where the body of the request enables word-level confidence.

curl  
-s  
-H  
 "Content-Type: application/json" 
  
 \ 
  
-H  
 "Authorization: Bearer 
 $( 
gcloud  
auth  
application-default  
print-access-token ) 
 " 
  
 \ 
  
https://speech.googleapis.com/v1p1beta1/speech:recognize  
 \ 
  
--data  
 '{ 
 "config": { 
 "encoding": "FLAC", 
 "sampleRateHertz": 16000, 
 "languageCode": "en-US", 
 "enableWordTimeOffsets": true, 
  "enableWordConfidence": true 
 }, 
 "audio": { 
 "uri": "gs://cloud-samples-tests/speech/brooklyn.flac" 
 } 
 }' 
 > 
word-level-confidence.txt

If the request is successful, the server returns a 200 OK HTTP status code and the response in JSON format, saved to a file named word-level-confidence.txt .

{
  "results": [
    {
      "alternatives": [
        {
          "transcript": "how old is the Brooklyn Bridge",
          "confidence": 0.98360395,
          "words": [
            {
              "startTime": "0s",
              "endTime": "0.300s",
              "word": "how",
              "confidence": 0.98762906
            },
            {
              "startTime": "0.300s",
              "endTime": "0.600s",
              "word": "old",
              "confidence": 0.96929157
            },
            {
              "startTime": "0.600s",
              "endTime": "0.800s",
              "word": "is",
              "confidence": 0.98271006
            },
            {
              "startTime": "0.800s",
              "endTime": "0.900s",
              "word": "the",
              "confidence": 0.98271006
            },
            {
              "startTime": "0.900s",
              "endTime": "1.100s",
              "word": "Brooklyn",
              "confidence": 0.98762906
            },
            {
              "startTime": "1.100s",
              "endTime": "1.500s",
              "word": "Bridge",
              "confidence": 0.98762906
            }
          ]
        }
      ],
      "languageCode": "en-us"
    }
  ]
}

Java

To learn how to install and use the client library for Speech-to-Text, see Speech-to-Text client libraries . For more information, see the Speech-to-Text Java API reference documentation .

To authenticate to Speech-to-Text, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  /** 
 * Transcribe a local audio file with word level confidence 
 * 
 * @param fileName the path to the local audio file 
 */ 
 public 
  
 static 
  
 void 
  
 transcribeWordLevelConfidence 
 ( 
 String 
  
 fileName 
 ) 
  
 throws 
  
 Exception 
  
 { 
  
 Path 
  
 path 
  
 = 
  
 Paths 
 . 
 get 
 ( 
 fileName 
 ); 
  
 byte 
 [] 
  
 content 
  
 = 
  
 Files 
 . 
 readAllBytes 
 ( 
 path 
 ); 
  
 try 
  
 ( 
 SpeechClient 
  
 speechClient 
  
 = 
  
 SpeechClient 
 . 
 create 
 ()) 
  
 { 
  
 RecognitionAudio 
  
 recognitionAudio 
  
 = 
  
 RecognitionAudio 
 . 
 newBuilder 
 (). 
 setContent 
 ( 
 ByteString 
 . 
 copyFrom 
 ( 
 content 
 )). 
 build 
 (); 
  
 // Configure request to enable word level confidence 
  
 RecognitionConfig 
  
 config 
  
 = 
  
 RecognitionConfig 
 . 
 newBuilder 
 () 
  
 . 
 setEncoding 
 ( 
 AudioEncoding 
 . 
 LINEAR16 
 ) 
  
 . 
 setSampleRateHertz 
 ( 
 16000 
 ) 
  
 . 
 setLanguageCode 
 ( 
 "en-US" 
 ) 
  
 . 
 setEnableWordConfidence 
 ( 
 true 
 ) 
  
 . 
 build 
 (); 
  
 // Perform the transcription request 
  
 RecognizeResponse 
  
 recognizeResponse 
  
 = 
  
 speechClient 
 . 
 recognize 
 ( 
 config 
 , 
  
 recognitionAudio 
 ); 
  
 // Print out the results 
  
 for 
  
 ( 
 SpeechRecognitionResult 
  
 result 
  
 : 
  
 recognizeResponse 
 . 
 getResultsList 
 ()) 
  
 { 
  
 // There can be several alternative transcripts for a given chunk of speech. Just use the 
  
 // first (most likely) one here. 
  
 SpeechRecognitionAlternative 
  
 alternative 
  
 = 
  
 result 
 . 
 getAlternatives 
 ( 
 0 
 ); 
  
 System 
 . 
 out 
 . 
 format 
 ( 
 "Transcript : %s\n" 
 , 
  
 alternative 
 . 
 getTranscript 
 ()); 
  
 System 
 . 
 out 
 . 
 format 
 ( 
  
 "First Word and Confidence : %s %s \n" 
 , 
  
 alternative 
 . 
 getWords 
 ( 
 0 
 ). 
 getWord 
 (), 
  
 alternative 
 . 
 getWords 
 ( 
 0 
 ). 
 getConfidence 
 ()); 
  
 } 
  
 } 
 }

Node.js

To learn how to install and use the client library for Speech-to-Text, see Speech-to-Text client libraries . For more information, see the Speech-to-Text Node.js API reference documentation .

To authenticate to Speech-to-Text, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  const 
  
 fs 
  
 = 
  
 require 
 ( 
 'fs' 
 ); 
 // Imports the Google Cloud client library 
 const 
  
 speech 
  
 = 
  
 require 
 ( 
 ' @google-cloud/speech 
' 
 ). 
 v1p1beta1 
 ; 
 // Creates a client 
 const 
  
 client 
  
 = 
  
 new 
  
 speech 
 . 
  SpeechClient 
 
 (); 
 /** 
 * TODO(developer): Uncomment the following lines before running the sample. 
 */ 
 // const fileName = 'Local path to audio file, e.g. /path/to/audio.raw'; 
 const 
  
 config 
  
 = 
  
 { 
  
 encoding 
 : 
  
 'FLAC' 
 , 
  
 sampleRateHertz 
 : 
  
 16000 
 , 
  
 languageCode 
 : 
  
 'en-US' 
 , 
  
 enableWordConfidence 
 : 
  
 true 
 , 
 }; 
 const 
  
 audio 
  
 = 
  
 { 
  
 content 
 : 
  
 fs 
 . 
 readFileSync 
 ( 
 fileName 
 ). 
 toString 
 ( 
 'base64' 
 ), 
 }; 
 const 
  
 request 
  
 = 
  
 { 
  
 config 
 : 
  
 config 
 , 
  
 audio 
 : 
  
 audio 
 , 
 }; 
 const 
  
 [ 
 response 
 ] 
  
 = 
  
 await 
  
 client 
 . 
 recognize 
 ( 
 request 
 ); 
 const 
  
 transcription 
  
 = 
  
 response 
 . 
 results 
  
 . 
 map 
 ( 
 result 
  
 = 
>  
 result 
 . 
 alternatives 
 [ 
 0 
 ]. 
 transcript 
 ) 
  
 . 
 join 
 ( 
 '\n' 
 ); 
 const 
  
 confidence 
  
 = 
  
 response 
 . 
 results 
  
 . 
 map 
 ( 
 result 
  
 = 
>  
 result 
 . 
 alternatives 
 [ 
 0 
 ]. 
 confidence 
 ) 
  
 . 
 join 
 ( 
 '\n' 
 ); 
 console 
 . 
 log 
 ( 
 `Transcription: 
 ${ 
 transcription 
 } 
 \n Confidence: 
 ${ 
 confidence 
 } 
 ` 
 ); 
 console 
 . 
 log 
 ( 
 'Word-Level-Confidence:' 
 ); 
 const 
  
 words 
  
 = 
  
 response 
 . 
 results 
 . 
 map 
 ( 
 result 
  
 = 
>  
 result 
 . 
 alternatives 
 [ 
 0 
 ]); 
 words 
 [ 
 0 
 ]. 
 words 
 . 
 forEach 
 ( 
 a 
  
 = 
>  
 { 
  
 console 
 . 
 log 
 ( 
 ` word: 
 ${ 
 a 
 . 
 word 
 } 
 , confidence: 
 ${ 
 a 
 . 
 confidence 
 } 
 ` 
 ); 
 });

Python

To learn how to install and use the client library for Speech-to-Text, see Speech-to-Text client libraries . For more information, see the Speech-to-Text Python API reference documentation .

To authenticate to Speech-to-Text, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  from 
  
 google.cloud 
  
 import 
 speech_v1p1beta1 
 as 
 speech 
 client 
 = 
 speech 
 . 
 SpeechClient 
 () 
 speech_file 
 = 
 "resources/Google_Gnome.wav" 
 with 
 open 
 ( 
 speech_file 
 , 
 "rb" 
 ) 
 as 
 audio_file 
 : 
 content 
 = 
 audio_file 
 . 
 read 
 () 
 audio 
 = 
 speech 
 . 
 RecognitionAudio 
 ( 
 content 
 = 
 content 
 ) 
 config 
 = 
 speech 
 . 
 RecognitionConfig 
 ( 
 encoding 
 = 
 speech 
 . 
 RecognitionConfig 
 . 
 AudioEncoding 
 . 
 LINEAR16 
 , 
 sample_rate_hertz 
 = 
 16000 
 , 
 language_code 
 = 
 "en-US" 
 , 
 enable_word_confidence 
 = 
 True 
 , 
 ) 
 response 
 = 
 client 
 . 
 recognize 
 ( 
 config 
 = 
 config 
 , 
 audio 
 = 
 audio 
 ) 
 for 
 i 
 , 
 result 
 in 
 enumerate 
 ( 
 response 
 . 
 results 
 ): 
 alternative 
 = 
 result 
 . 
 alternatives 
 [ 
 0 
 ] 
 print 
 ( 
 "-" 
 * 
 20 
 ) 
 print 
 ( 
 f 
 "First alternative of result 
 { 
 i 
 } 
 " 
 ) 
 print 
 ( 
 f 
 "Transcript: 
 { 
 alternative 
 . 
 transcript 
 } 
 " 
 ) 
 print 
 ( 
 "First Word and Confidence: ( 
 {} 
 , 
 {} 
 )" 
 . 
 format 
 ( 
 alternative 
 . 
 words 
 [ 
 0 
 ] 
 . 
 word 
 , 
 alternative 
 . 
 words 
 [ 
 0 
 ] 
 . 
 confidence 
 ) 
 ) 
 return 
 response 
 . 
 results

Use a remote file

Java

To learn how to install and use the client library for Speech-to-Text, see Speech-to-Text client libraries . For more information, see the Speech-to-Text Java API reference documentation .

To authenticate to Speech-to-Text, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  /** 
 * Transcribe a remote audio file with word level confidence 
 * 
 * @param gcsUri path to the remote audio file 
 */ 
 public 
  
 static 
  
 void 
  
 transcribeWordLevelConfidenceGcs 
 ( 
 String 
  
 gcsUri 
 ) 
  
 throws 
  
 Exception 
  
 { 
  
 try 
  
 ( 
 SpeechClient 
  
 speechClient 
  
 = 
  
 SpeechClient 
 . 
 create 
 ()) 
  
 { 
  
 // Configure request to enable word level confidence 
  
 RecognitionConfig 
  
 config 
  
 = 
  
 RecognitionConfig 
 . 
 newBuilder 
 () 
  
 . 
 setEncoding 
 ( 
 AudioEncoding 
 . 
 FLAC 
 ) 
  
 . 
 setSampleRateHertz 
 ( 
 44100 
 ) 
  
 . 
 setLanguageCode 
 ( 
 "en-US" 
 ) 
  
 . 
 setEnableWordConfidence 
 ( 
 true 
 ) 
  
 . 
 build 
 (); 
  
 // Set the remote path for the audio file 
  
 RecognitionAudio 
  
 audio 
  
 = 
  
 RecognitionAudio 
 . 
 newBuilder 
 (). 
 setUri 
 ( 
 gcsUri 
 ). 
 build 
 (); 
  
 // Use non-blocking call for getting file transcription 
  
 OperationFuture<LongRunningRecognizeResponse 
 , 
  
 LongRunningRecognizeMetadata 
>  
 response 
  
 = 
  
 speechClient 
 . 
 longRunningRecognizeAsync 
 ( 
 config 
 , 
  
 audio 
 ); 
  
 while 
  
 ( 
 ! 
 response 
 . 
 isDone 
 ()) 
  
 { 
  
 System 
 . 
 out 
 . 
 println 
 ( 
 "Waiting for response..." 
 ); 
  
 Thread 
 . 
 sleep 
 ( 
 10000 
 ); 
  
 } 
  
 // Just print the first result here. 
  
 SpeechRecognitionResult 
  
 result 
  
 = 
  
 response 
 . 
 get 
 (). 
 getResultsList 
 (). 
 get 
 ( 
 0 
 ); 
  
 // There can be several alternative transcripts for a given chunk of speech. Just use the 
  
 // first (most likely) one here. 
  
 SpeechRecognitionAlternative 
  
 alternative 
  
 = 
  
 result 
 . 
 getAlternativesList 
 (). 
 get 
 ( 
 0 
 ); 
  
 // Print out the result 
  
 System 
 . 
 out 
 . 
 printf 
 ( 
 "Transcript : %s\n" 
 , 
  
 alternative 
 . 
 getTranscript 
 ()); 
  
 System 
 . 
 out 
 . 
 format 
 ( 
  
 "First Word and Confidence : %s %s \n" 
 , 
  
 alternative 
 . 
 getWords 
 ( 
 0 
 ). 
 getWord 
 (), 
  
 alternative 
 . 
 getWords 
 ( 
 0 
 ). 
 getConfidence 
 ()); 
  
 } 
 }

Node.js

To learn how to install and use the client library for Speech-to-Text, see Speech-to-Text client libraries . For more information, see the Speech-to-Text Node.js API reference documentation .

To authenticate to Speech-to-Text, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  // Imports the Google Cloud client library 
 const 
  
 speech 
  
 = 
  
 require 
 ( 
 ' @google-cloud/speech 
' 
 ). 
 v1p1beta1 
 ; 
 // Creates a client 
 const 
  
 client 
  
 = 
  
 new 
  
 speech 
 . 
  SpeechClient 
 
 (); 
 /** 
 * TODO(developer): Uncomment the following line before running the sample. 
 */ 
 // const uri = path to GCS audio file e.g. `gs:/bucket/audio.wav`; 
 const 
  
 config 
  
 = 
  
 { 
  
 encoding 
 : 
  
 'FLAC' 
 , 
  
 sampleRateHertz 
 : 
  
 16000 
 , 
  
 languageCode 
 : 
  
 'en-US' 
 , 
  
 enableWordConfidence 
 : 
  
 true 
 , 
 }; 
 const 
  
 audio 
  
 = 
  
 { 
  
 uri 
 : 
  
 gcsUri 
 , 
 }; 
 const 
  
 request 
  
 = 
  
 { 
  
 config 
 : 
  
 config 
 , 
  
 audio 
 : 
  
 audio 
 , 
 }; 
 const 
  
 [ 
 response 
 ] 
  
 = 
  
 await 
  
 client 
 . 
 recognize 
 ( 
 request 
 ); 
 const 
  
 transcription 
  
 = 
  
 response 
 . 
 results 
  
 . 
 map 
 ( 
 result 
  
 = 
>  
 result 
 . 
 alternatives 
 [ 
 0 
 ]. 
 transcript 
 ) 
  
 . 
 join 
 ( 
 '\n' 
 ); 
 const 
  
 confidence 
  
 = 
  
 response 
 . 
 results 
  
 . 
 map 
 ( 
 result 
  
 = 
>  
 result 
 . 
 alternatives 
 [ 
 0 
 ]. 
 confidence 
 ) 
  
 . 
 join 
 ( 
 '\n' 
 ); 
 console 
 . 
 log 
 ( 
 `Transcription: 
 ${ 
 transcription 
 } 
 \n Confidence: 
 ${ 
 confidence 
 } 
 ` 
 ); 
 console 
 . 
 log 
 ( 
 'Word-Level-Confidence:' 
 ); 
 const 
  
 words 
  
 = 
  
 response 
 . 
 results 
 . 
 map 
 ( 
 result 
  
 = 
>  
 result 
 . 
 alternatives 
 [ 
 0 
 ]); 
 words 
 [ 
 0 
 ]. 
 words 
 . 
 forEach 
 ( 
 a 
  
 = 
>  
 { 
  
 console 
 . 
 log 
 ( 
 ` word: 
 ${ 
 a 
 . 
 word 
 } 
 , confidence: 
 ${ 
 a 
 . 
 confidence 
 } 
 ` 
 ); 
 });

Python

To learn how to install and use the client library for Speech-to-Text, see Speech-to-Text client libraries . For more information, see the Speech-to-Text Python API reference documentation .

To authenticate to Speech-to-Text, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  from 
  
 google.cloud 
  
 import 
 speech_v1p1beta1 
 as 
 speech 
 def 
  
 transcribe_file_with_word_level_confidence 
 ( 
 audio_uri 
 : 
 str 
 ) 
 - 
> str 
 : 
  
 """Transcribe a remote audio file with word level confidence. 
 Args: 
 audio_uri (str): The Cloud Storage URI of the input audio. 
 E.g., gs://[BUCKET]/[FILE] 
 Returns: 
 The generated transcript from the audio file provided with word level confidence. 
 """ 
 client 
 = 
 speech 
 . 
 SpeechClient 
 () 
 # Configure request to enable word level confidence 
 config 
 = 
 speech 
 . 
 RecognitionConfig 
 ( 
 encoding 
 = 
 speech 
 . 
 RecognitionConfig 
 . 
 AudioEncoding 
 . 
 FLAC 
 , 
 sample_rate_hertz 
 = 
 44100 
 , 
 language_code 
 = 
 "en-US" 
 , 
 enable_word_confidence 
 = 
 True 
 , 
 # Enable word level confidence 
 ) 
 # Set the remote path for the audio file 
 audio 
 = 
 speech 
 . 
 RecognitionAudio 
 ( 
 uri 
 = 
 audio_uri 
 ) 
 # Use non-blocking call for getting file transcription 
 response 
 = 
 client 
 . 
 long_running_recognize 
 ( 
 config 
 = 
 config 
 , 
 audio 
 = 
 audio 
 ) 
 . 
 result 
 ( 
 timeout 
 = 
 300 
 ) 
 transcript_builder 
 = 
 [] 
 for 
 i 
 , 
 result 
 in 
 enumerate 
 ( 
 response 
 . 
 results 
 ): 
 alternative 
 = 
 result 
 . 
 alternatives 
 [ 
 0 
 ] 
 transcript_builder 
 . 
 append 
 ( 
 "-" 
 * 
 20 
 ) 
 transcript_builder 
 . 
 append 
 ( 
 f 
 " 
 \n 
 First alternative of result 
 { 
 i 
 } 
 " 
 ) 
 transcript_builder 
 . 
 append 
 ( 
 f 
 " 
 \n 
 Transcript: 
 { 
 alternative 
 . 
 transcript 
 } 
 " 
 ) 
 transcript_builder 
 . 
 append 
 ( 
 " 
 \n 
 First Word and Confidence: ( 
 {} 
 , 
 {} 
 )" 
 . 
 format 
 ( 
 alternative 
 . 
 words 
 [ 
 0 
 ] 
 . 
 word 
 , 
 alternative 
 . 
 words 
 [ 
 0 
 ] 
 . 
 confidence 
 ) 
 ) 
 transcript 
 = 
 "" 
 . 
 join 
 ( 
 transcript_builder 
 ) 
 print 
 ( 
 transcript 
 ) 
 return 
 transcript

Enable word-level confidence Stay organized with collections Save and categorize content based on your preferences.

Word-level confidence

Enable word-level confidence in a request

Use a local file

Protocol

Java

Node.js

Python

Use a remote file

Java

Node.js

Python

Enable word-level confidence