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TLV320AIC3120EVM-U: Regarding Noise issue with ELECTRET CONDENSER MICROPHONE.

Soundappan T
Prodigy 50 points
Part Number: TLV320AIC3120EVM-U
Other Parts Discussed in Thread: TLV320AIC3120,

Tool/software:

Hi Team,

We are Evaluating the TLV320AIC3120 Series Audio codec with TLV320AIC3120EVM-U, we conducted the test with two different analog mic specification as attached below for your reference. We faced an issue that along with the recorded voice additional noise coupled to the recording and while play back those audios, amplitude seems very low.

We used the script 7.3.11 given in Codec datasheet for testing. Can you provide some inputs about how to nullify this issue.

Mic type: ELECTRET CONDENSER MICROPHONE

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  • 0
    TI__Mastermind 28220 points

    Hi,

    Can you clarify, when recording and playback at the same time, the playback audio is coupling back onto the recording path? Or are you experiencing noise on the recording path regardless. What is the profile of the noise you are measuring? 

    Thanks,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Prodigy 50 points

    Hi,

    Thanks for your reference, we experimented recording and playback separately. I am experiencing noise in the recording path. I didn't have any noise level data with me, but we are experiencing a white noise sound effect from the speaker along with the recorded audio.

  • 0 in reply to Soundappan T
    TI__Mastermind 28220 points

    Hi,

    Even in environments we consider quiet to our ears, microphones pick up any kind of noise, so it's not unusual to get white noise. This is especially true since the EVM has no noise conditioning circuits on the input pins. 

    However without noise level data I cannot say if it's expected or not. I would compare using a signal generator, which is much cleaner, on the input to see if the noise remains or if it is unique to microphones. 

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Prodigy 50 points

    Hi Jeff McPherson,

    I can understand that white noise is unavoidable, since recorded Audio's amplitude itself very low, can you suggest some technique to increase the recorded audio amplitude, with below mentioned specification of mic

    MIC.pdf

  • 0 in reply to Soundappan T
    TI__Mastermind 28220 points

    Hi,

    Mic signals are typically very low at the output. You will likely need to increase the ADC gain to get an acceptable output level. 

    Your microphone is omnidirectional so it should pick up sources from all directions. This is both a good and bad thing since you can easily pick up both the voice and outside noise this way. Take care that the mic is much closer to the intended source than external noise sources.

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Prodigy 50 points

    Hi Jeff McPherson,

    Thanks for your Response, we have experimented with maximum ADC Gain of mic, even though we can't achieve a significant level of amplitude gain from the Mic. I understood noise can't be avoided, we are ok with that, kindly suggest any other methods to increase the amplitude of Mic's output. or suggest any specifications of mic which will be suitable for audio recording with TLV320AIC3120 Series.

  • 0 in reply to Soundappan T
    TI__Mastermind 28220 points

    Hi,

    Can you measure the output of the microphone? What RMS voltage are you getting?

    Also have you connected the condenser mic to some kind of power source such as MICBIAS?

    Best regards,

    Jeff McPherson