Monitor sound in real time using Python

i think that will be difficult - normally sound cards are designed for the human frequency range - thats something from 20Hz up to 20kHz.

i don't have looked in the datasheet - eventually you find some infos for the supported frequency.

i think some time ago i saw an device with an special microphone that was designed for this high frequencys - combined with a circuit that transforms the high frequencys to the range that humans can here it -

so with something like this you could just monitoring the input level and trigger your action if  it rises above a certain level...

have fun :-)

sunny greetings

stefan

The data sheet can lead you to believe that the DMICs only support frequencies up to 10 kHz.

But apparently they work well for recording bats.

Raspberry Pi • View topic - Bat detector

pywws - South Somerset Weather

--

Ragnar

The WM7220 microphone may well be rather less than ideal for recording very high frequencies - the Wolfson data sheet shows the response starting to rise at 10kHz and it's normal for the sensitivity to plummet after a resonant peak. Since Wolfson don't say what happens next there is obviously no guarantee of the response at higher frequencies.

I'm not really into bats but the obvious thing to do is to pest Wolfson to give some indication about the response of the microphone at higher frequencies.

MK

Beyond the microphone issue, how do you control

the recording by the wolfson card using python?

I'd like to set up a wildlife recording device that

would activate recording according to a predefined time table

(i.e. 5:00 to 5:25; 6:30 to 7:00 etc)

I understand one issue would be starting up the RaspberryPy at 5:00

(or rather at 4:55) (maybe just with an external switch timer), get the python script activated upon start-up and

then let the script control recording periods.

Thanks

Agus

Sorry I can't help you here Agustin, I know a bit about microphones and signal processing but nothing about RPi software - perhaps someone elese can help you out.

MK

I have successfully recorded bats using the on-board DMICs - picking up Pipistrelles (peak frequency 46kHz).

I also made an ultrasonic microphone using a Panasonic WM61A electret microphone plugged into the headphone socket on the Wolfson card, which also records ultrasound frequencies.

SNARP is a sound-activated recorder written in Python. I'm not sure if you actually want to record, but at least it might serve as base.

As it takes sound from standard input you could use sox to record from the sound card, use sox's "highpass" or "sinc" filters to strip out the lower frequencies and then pipe the result into SNARP.

--

Ragnar