Audio sensor

[ibwev]

Is there a circuit or a sensor that can detect a range of high frequency sounds and send a high signal to a microprocessor when the desired sound is detected?

 

[MikeMl]

How wide a range of frequencies?

An electret microphone, followed by amplification, followed by a high-pass filter, followed by a rectifier circuit, followed by a low-pass filter, followed by a threshold detector with hysteresis comes to mind...

 

[ibwev]

I would need it to detect a sound similar to the whistle a teapot makes when the water boils. Can you suggest a resource that a hobbyist might study to learn how to assemble the above circuit?

 

[MikeMl]

I would need it to detect a sound similar to the whistle a teapot makes when the water boils. Can you suggest a resource that a hobbyist might study to learn how to assemble the above circuit?

I would start by hooking a microphone to PC oscilloscope freeware which includes an audio spectrum analyzer. Feed in your whistle. Diddle the gain until you get audio clipping. Back off a bit. That will tell you how much gain you need after the mic.

Look at the spectrum of the sounds you want to detect. Find what frequencies are most prominent. That will tell you what kind of high-pass (or possibly bandpass) filtering will select your sound without including other environmental noise.

If there is any "cadence", rise, duration or other temporal information in the sound, that will effect the low-pass filtering after the detector.

 

[dougy83]

You can also have a look at a tone detector, e.g. LM567. These can provide a digital output level when the tone is detected.

 

[jpanhalt]

Detecting a particular sound is different than detecting a particular frequency. Which is it that you need to do?

Here is a short list of microcontroller-based projects for detecting particular frequencies:

Detects frequencies >=set value
https://pic-microcontroller.com/frequency-detector-using-pic-12f683-processor/

Frequency counter:
https://picboard.blogspot.com/2010/09/experiment-no-6-pic12f683-timer1-used.html

18F4550 audio spectrum analyzer:
https://www.waitingforfriday.com/index.php/Real-Time_Audio_Spectrum_Analyser

Instructable DTMF analyzer;
https://www.instructables.com/id/DTMF-Touch-Tone-Decoder-Using-Microchip-PIC-Microp/?ALLSTEPS

The spectrum analyzer (third in the list) could also help in detecting a particular sound.

John