Inconsistencies in IPA Pronunciation in Text to Speech

Question

Hi,

I'm using SSML to ensure specific pronunciation, however, I'm experiencing some inconsistencies.

For example, here's the word 'would':

<speak version='1.0' xmlns='http://www.w3.org/2001/10/synthesis' xml:lang='en-US'>
      <voice name='en-US-AvaNeural'>
            <phoneme alphabet="ipa" ph="wʊd">would</phoneme>
      </voice>
</speak>

It pronounces the word exactly as expected.

Now if I want to break the word down into individual sounds and just pronounce the 'ʊ' sound, I would use this:

<speak version='1.0' xmlns='http://www.w3.org/2001/10/synthesis' xml:lang='en-US'>
	<voice name='en-US-AvaNeural'>
		<phoneme alphabet="ipa" ph="ʊ">oul</phoneme>
	</voice>            
</speak>

However, now it sounds like it's saying the letter 'O'. I expect that 'ʊ' would be pronounced the same in both cases.

Can anyone offer any insight into why this may be happening? Thank you.

Answer 1

Hi Chris Enzweiler,

Welcome to Microsoft Q&A Forum, thank you for posting your query here!

While using SSML to control pronunciation, you might encounter inconsistencies, especially with isolated phonemes. For example, the word “would” is pronounced correctly with the IPA phoneme ‘wʊd’. However, isolating the ‘ʊ’ sound might result in it being pronounced like the letter ‘O’ due to the TTS system’s on context for accurate pronunciation.

Example:

XML
<speak version='1.0' xmlns='http://www.w3.org/2001/10/synthesis' xml:lang='en-US'>
    <voice name='en-US-AvaNeural'>
        <phoneme alphabet="ipa" ph="wʊd">would</phoneme>
    </voice>
</speak>

This correctly pronounces “would” as expected.

However, isolating the ‘ʊ’ might sound like the letter ‘O’ due to lack of context.

To improve accuracy, try embedding the phoneme within a minimal context

This approach helps the TTS engine produce the desired sound more accurately.

Hope this helps. Do let us know if you any further queries.

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