How to detect high frequency sound?

[dxpwny]

How to detect high frequency sound ?

I need some advice on how I might accomplish the detection of very high frequency sound. I do not know the source of the sound, or where is comes from (sorry - I don't care and can't answer any questions about that). I also do not know the exact frequency - or range. I know it is higher then what I can hear, so perhaps 20 - 50 khz <?>.

I'd be happy just detecting that a sound above a certain the frequency threshold was present - not necessarily the amplitude, and log the event to a text file with a time stamp.

As part of the project I'm already using an 8051, tied to my PCs serial port, to detect something else. So, a simple logic high when the sound is detected is fine.

I'd have ideas if the sound were 10khz, but it isn't and I don't know what device is best to detect such high frequency.

Thanks for helping.

 

[G4BCH]

Re: How to detect high frequency sound ?

Almost any electret microphone will work up to around 50kHz. Knowles make a number that are characterised beyond the normal 10kHz. Just put a high pass filter after it to reduce lower frequency audio. An amplifier may be needed as well. You can then process the signal however you like.
Look up bat detectors to get plenty of ideas of what you could do.

 

[C1500]

Re: How to detect high frequency sound ?

https://www.directeddealers.com/manuals/ig/accessories/N506T.pdf

They use high freq glass break sensors in auto security systems - directed electronics 506t was probably the most popular - it gives a ground out put when the microphone triggers an event (glass breaking). I don't know if this could work for you but may be worth looking into.