Client uses defaultFrequency = 24kHz on different formats than pcm16

[ovistoica]

Hello, I noticed that betweem client.js or conversation.js the defaultFrequency at which we calculate how much audio to truncate is always 24kHz regardless of the audio format.

Shouldn't this be updated if the input/output frequency changes? For example if audio format is changed to MULAW for phone calls, the defaultFrequency should change to 8KHz.

Let me know if I'm wrong here, if not, I'm happy to open a PR