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My wife has extremely good hearing. Good enough that the 19 kHz flyback transformer noise from some older CRT TVs bothered her. Recently I bought an induction cooktop and when I turned it on she screamed in pain. It injured her ear enough that it has been sore for 3 weeks. At first I thought it was just that particular unit, so I got another one and she said the beeper was painfully loud. I took out the beeper and she still felt the pain, 25 feet away. Me, I don't hear a thing, but I am 70 dB down or more from 4 kHz up.

I know that induction heating is in the 20KHz and up frequency range. So I thought I would try to find a mic that would work up to 30-40 kHz, hook up to my scope and see what is going on. So the mic does not need to have a flat response, it just needs to capture the frequency. Inexpensive is good, too. It is true I could measure the frequency directly with my scope, but I thought a mic might help identify where the high freq vibration is coming from.

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Check out something like the STMicroelectronics IMP23ABSUTR. It's easy to use, reasonably sensitive to 80kHz or similar, and pretty cheap. It's, well, not particularly fun to hand-solder though. Better get a few spares, or an evaluation board coming pre-soldered.

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  • Well, DUH on me. I have ordered from them many times but never thought about them for microphones. Definitely looks viable. I know what you mean about solder-ability. When I started out pin pitch was 0.1", about 2.5 mm. I am 69 now and one of the major disadvantages of working from home is the pin pitch of the microcontroller I am using is down to 0.5 mm. I am in Dallas and the office in Boston, can't just run down to the lab and ask a tech to tack on some 30 gauge wire anymore. Singles are less than $3 each. Eval board is $30. I may try a couple of singles first. Great info, many thanks. Apr 24, 2023 at 14:00
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