Whispering

<amazon:effect name="whispered">

This tag is currently supported only by the standard TTS format.

This tag indicates that the input text should be spoken in a whispered voice rather than as normal speech. This can be used with any of the voices in the Amazon Polly Text-to-Speech portfolio.

This uses the following syntax:

<amazon:effect name="whispered">text</amazon:effect>

For example:

<speak>
     <amazon:effect name="whispered">If you make any noise, </amazon:effect> 
     she said, <amazon:effect name="whispered">they will hear us.</amazon:effect>
</speak>

In this case, the synthesized speech spoken by the character is whispered, but the phrase "she said" is spoken in the normal synthesized speech of the selected Amazon Polly voice.

You can enhance the "whispered" effect by slowing down the prosody rate by up to 10%, depending on the effect you want.

For example:

<speak>
     When any voice is made to whisper, <amazon:effect name="whispered">
     <prosody rate="-10%">the sound is slower and quieter than normal speech
     </prosody></amazon:effect>
</speak>

When generating speech marks for a whispered voice, the audio stream must also include the whispered voice to ensure that the speech marks match the audio stream.