Background low-frequency, fluctuating tone in recordings

ArmDeveloperEcosystem / microphone-library-for-pico

Capture audio from a microphone on your Raspberry Pi Pico or any RP2040 based board. 🎤

Apache License 2.0

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Background low-frequency, fluctuating tone in recordings #7

Closed iovsiann closed 2 years ago

iovsiann commented 2 years ago

Hi, thank you for the sample code. Microphone sound capture works, but there it comes with background low-frequency tone that fluctuates (on/off a few times per second). I've attached a WAV recording - the fluctuating background tone is easy to hear at the end of the recording. Also, it appears that the audio has some breaks in it (i.e. sound gets missing momentarily). untitled.wav.zip Any help would be much appreciated. Thank you

sandeepmistry commented 2 years ago

Hi @iovsiann,

I've tried this USB microphone example again with an RPi Pico + Adafruit PDM mic. on a breadboard, then using Quicktime to record on macOS, and it seems ok here:

hello.m4a.zip

Would you be able to share more details of your setup?

which board and microphone + photo of wiring
what OS and app you are using for the recording
I think you are using the USB mic. example but please confirm

I'm wondering if the PDM mic. is configured for the wrong channel, for the MP34DT01-M I have, I've grounded the L/R (SEL) pin, so data is valid when the CLK is low. See section 6 of MP34DT01-M.pdf.

iovsiann commented 2 years ago

@sandeepmistry, thank you for checking. It seems the problem is on my side. I was using VMPlayer running Ubuntu 18.04 to capture sound. When I plug the Pico in a real Ubuntu PC, the mic works. I also tried NVIDIA Nano running Ubuntu and it worked as well.

sandeepmistry commented 2 years ago

@iovsiann great to hear things are working! Thanks for diagnosing the issue and sharing the outcome!