Poor HFP voice audio quality, gender indistinguishable, high background noise—how to troubleshoot the cause or improve audio quality?

Troubleshooting
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  1. The codec is forced to use CVSD; using mSBC yields similar results. Upon receiving BTS2MU_HF_AUDIO_CONN_CFM, audio_open is called using I2S output, with AUDIO_DATA_SIZE set to 640.

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  1. This is the I2S configuration.
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Unable to distinguish gender and with high background noise, suspecting incorrect sampling rate or I2S format error. You can first directly export the audio data from RAM and play it on a PC using different sampling rates to confirm whether the audio data is correct and determine the actual sampling rate.