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Finding chirping noises

Every now & again we get a question about how to find the source of a chirping noise. Mechanic’s stethoscopes are great, and we all know about accelerometers (piezoelectric sensors that can send a signal to a scope) but I go to wondering something. Has anyone here ever tried a unidirectional microphone to find the source of a chirp or squeak? It seems such a simple idea, but I’ve never heard of it used.

Thoughts? Inputs? Comments? Criticisms? Experiences?

A stethoscope is probably the best way to find the source of any engine noise but I’ve had great success with a piece of garden hose. I’ve never tried a microphone before.

I wouldn’t know what to do with a microphone. I’ve tried a hose, pipe, screwdriver, stethoscope, etc. but have never been able to isolate a noise myself any better than just my naked ear. So its either replace likely parts or off to someone more skilled.

I think I’ll pick up a cheap audio unit (probably a Karaoke setup… I still have a very good unidirectional mic from my guitar playing days) and try it. I’ll let you all know how well it works (or doesn’t).

One time trying to hear a faint sound coming from the alternator area, I thumb-tacked a paper cup to the end of a ~1/2 inch diameter wooden dowel, listening to the paper cup side, that worked pretty well if you can put something up against the part you are trying to diagnose. A directional microphone might be better if you just want to listen to a certain place and direction, without touching anything.

I actually have a mechanic’s stethoscope, but I’m going to try a unidirectional mic just out of curiosity. It’s something I’ve never heard of anybody trying.