Applying lexicons (Synthesizing Speech)

The lexicons you use must conform to the Pronunciation Lexicon Specification (PLS) W3C recommendation. For more information, see Pronunciation Lexicon Specification (PLS) Version 1.0 on the W3C website.

Console

The following procedure demonstrates how to apply a lexicon to your input text by applying the W3c.pls lexicon to substitute "World Wide Web Consortium" for "W3C". If you apply multiple lexicons to your text they are applied in a top-down order with the first match taking precedence over later matches. A lexicon is applied to the text only if the language specified in the lexicon is the same as the language chosen.

You can apply a lexicon to plain text or SSML input.

Example – Applying the W3C.pls Lexicon

To create the lexicon you'll need for this exercise, see Uploading a lexicon. Use a plain text editor to create the W3C.pls lexicon shown at the top of the topic. Remember where you save this file.

To apply the W3C.pls lexicon to your input

In this example we introduce a lexicon to substitute "World Wide Web Consortium" for "W3C". Compare the results of this exercise with that of Using SSML on the console for both US English and another language.

1. Sign in to the AWS Management Console and open the Amazon Polly console at https://console.aws.amazon.com/polly/.

2. Do one of the following:

   • Turn off SSML and then type or paste this text into the text input box.

     He was caught up in the game. 
     In the middle of the 10/3/2014 W3C meeting 
     he shouted, "Score!" quite loudly.

   • Turn on SSML and then type or paste this text into the text input box.

     <speak>He wasn't paying attention.<break time="1s"/>
     In the middle of the 10/3/2014 W3C meeting 
     he shouted, "Score!" quite loudly.</speak>

3. From the Language list, choose English, US, then choose the voice you want to use for this text.

4. Expand Additional settings and turn on Customize pronunciation.

5. From the list of lexicons, choose W3C (English, US).

   If the W3C (English, US) lexicon is not listed, choose Upload lexicon and upload it, then choose it from the list. To create this lexicon, see Uploading a lexicon.

6. To listen to the speech immediately, choose Listen.

7. To save the speech to a file,

   1. Choose Download.

   2. To change to a different file format, turn on Speech file format settings, choose the file format you want, and then choose Download.

Repeat the previous steps, but choose a different language and notice the difference in the output.

AWS CLI

In a call to SynthesizeSpeech, you can specify multiple lexicons. In this case, the first lexicon specified (in order from left to right) overrides any preceding lexicons.

Consider the following two lexicons. Note that each lexicon describes different aliases for the same grapheme W3C.

• Lexicon 1: w3c.pls

  <?xml version="1.0" encoding="UTF-8"?>
  <lexicon version="1.0" 
        xmlns="http://www.w3.org/2005/01/pronunciation-lexicon"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
        xsi:schemaLocation="http://www.w3.org/2005/01/pronunciation-lexicon 
          http://www.w3.org/TR/2007/CR-pronunciation-lexicon-20071212/pls.xsd"
        alphabet="ipa" xml:lang="en-US">
    <lexeme>
      <grapheme>W3C</grapheme>
      <alias>World Wide Web Consortium</alias>
    </lexeme>
  </lexicon>

• Lexicon 2: w3cAlternate.pls

  <?xml version="1.0" encoding="UTF-8"?>
  <lexicon version="1.0"
        xmlns="http://www.w3.org/2005/01/pronunciation-lexicon"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://www.w3.org/2005/01/pronunciation-lexicon
          http://www.w3.org/TR/2007/CR-pronunciation-lexicon-20071212/pls.xsd"
        alphabet="ipa" xml:lang="en-US">
  
    <lexeme> 
      <grapheme>W3C</grapheme>
      <alias>WWW Consortium</alias>
    </lexeme>
  </lexicon>

Suppose you store these lexicons as w3c and w3cAlternate respectively. If you specify lexicons in order (w3c followed by w3cAlternate) in a SynthesizeSpeech call, the alias for W3C defined in the first lexicon has precedence over the second. To test the lexicons, do the following:

1. Save the lexicons locally in files called w3c.pls and w3cAlternate.pls.

2. Upload these lexicons using the put-lexicon AWS CLI command.

   • Upload the w3c.pls lexicon and store it as w3c.

     aws polly put-lexicon \
     --name w3c \
     --content file://w3c.pls 
     

   • Upload the w3cAlternate.pls lexicon on the service as w3cAlternate.

     aws polly put-lexicon \
     --name w3cAlternate \
     --content file://w3cAlternate.pls 

3. Run the synthesize-speech command to synthesize sample text to an audio stream (speech.mp3), and specify both lexicons using the lexicon-name parameter.

   aws polly synthesize-speech \
   --text 'PLS is a W3C recommendation' \
   --voice-id Joanna \
   --output-format mp3 \
   --lexicon-names '["w3c","w3cAlternative"]' \
   speech.mp3

4. Test the resulting speech.mp3. It should read as follows:

   PLS is a World Wide Web Consortium recommendation