Siri voice (US English male, compact) issue when encountering word like "hmm"

Hi,
ok, if you tell voice over to read the word, "hmm" (i found it on whats app) siri us english male default, not enhanced, will read it with a slower speed than default. if it only read the "hmm" with slower speeds, that is understandable, but this voice also reads the things that is after the word "hmm" with the slower rate. Sorry for bad english and sorry if offtopic or duplicated. thanks.

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also,

it will happen (to me) if your are receiving the message, voice over reads the sender's number then the message containing "hmm". but not if you type it in the edit box (on whats app) to send the message and read it back.