Looking for an appropriate microphone

[crelf]

Howdy all - I just picked up the tail end of a project that needs to add a microphone. There's an existing NI USB-4431 (102.4 kS/s, ±10 V) in the stand that has a spare channel, and we'd like to acquire a couple of things:

• The UUT (think handheld device) emits 2 tones when under test (1.2kHz and 2.4kHz): I need to acquire and calc the frequency (let's say with an accuracy of +/- 50Hz)
• The UUT also has a vibrate alert: I need to determine if it's on or off, nothing more.

Anyone got a favorite microphone that would fit the requirements? I'd rather not reinvent the wheel if at all possible.

[Mark Smith]

I don't have a particular microphone to recommend, but if you can attach the microphone to the UUT (with a simple clip or strap or such) then a simple contact mic would work well. You won't have to worry about ambient noise and the vibration, in particular, will be easier to detect if most of the energy from the signal couples directly into the transducer. Also, you can save yourself a lot of headaches by getting a simple commercial mic preamp to condition the mic signal and convert it to audio line level before you send it to the DAQ. I would think you get everything you need for <$150 - maybe a lot less.

Mark

[Phillip Brooks]

Howdy all - I just picked up the tail end of a project that needs to add a microphone. There's an existing NI USB-4431 (102.4 kS/s, ±10 V) in the stand that has a spare channel, and we'd like to acquire a couple of things:

• The UUT (think handheld device) emits 2 tones when under test (1.2kHz and 2.4kHz): I need to acquire and calc the frequency (let's say with an accuracy of +/- 50Hz)
• The UUT also has a vibrate alert: I need to determine if it's on or off, nothing more.

Anyone got a favorite microphone that would fit the requirements? I'd rather not reinvent the wheel if at all possible.

Completely unrelated, but would this microphone do?

[crelf]

You won't have to worry about ambient noise and the vibration, in particular, will be easier to detect if most of the energy from the signal couples directly into the transducer.

Good idea - thanks Mark.

Completely unrelated, but would this microphone do?

Wow - that's really cool. I mean, there's not much technologically inventive about it, but an excellent application of the technology.

[Cat]

Completely unrelated, but would this microphone do?

Cool! Kind of like reverse beam-forming. Hmm...