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Minimum Bit Depth for Audio ADC

Ryan May
Genius 13700 points
Other Parts Discussed in Thread: ADS7042

Hello,

I am working to develop a low power headset and i am trying to select a proper ADC for an analog mic.

Looking through the portfolio here all of the listed audio ADCs are 24 bit:

This would be for conversational audio so I can not imagine that I need that many bits. 

My question is can I use a 12, 14, or 16 bit converter to sample my audio signal with "acceptable" results for digitizing the human voice?

  • 0
    TI__Mastermind 27850 points
    Hi Ryan,

    I am assuming since you are going to for "acceptable" audio, the project is cost sensitive. This means you are going to be looking at hardware controlled parts. While These all say they operate at 24 bits, it could be possible hey can work at 16 bit resolution, and you would do this by operating setting the BCK ratio to 32 *FS. This may or may not work and would need to be tested. And just because the device is working at 24 bits, you can set up the device that's getting the data to only look at 16 bits, or less.

    Most cheap microphones used for voice can only perform up to around -70 dB SNR, which is about 12 bits. So yes 12 bits could be acceptable, and its questionable if you can force our HW controlled ADCs to 16 bits, but definitely not 12 bit output. A way around this is to have the audio sink just look at the desired number of bits starting with the MSB.

    Justin
  • 0 in reply to Justin Bohr
    TI__Genius 13700 points

    Hello Justin,

    Thank you for your support.

    I am actually trying to explore using something like the ADS7042 or the ADS886x fmaily for a low power ADC for analog mic in a headset application with potential applications to a voice sensor node or speaker phone.