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Topic: Arduino-Microphone (Read 609 times) previous topic - next topic

Sara94alzate

Hello everybody...

I'm trying to develop an arduino Duo program with a microphone to get sound signal and then be able to process it, but I need some audio-module between these two and I've been looking for something but I have not got any luck. So, if anyone knows about some audio-module to facilitate the connection I wouldbe very thankful.   

Sara

DVDdoug

You need a preamp to boost the few-millivolt microphone signal to around line level (about 1V).    Then you need to bias the signal so that you can read the negative-half of the AC audio signal.

Electret condenser mics need about 5V power and studio condensers require 48V phantom power.   Dynamic mics don't need power (but they still need a preamp).


The easiest way to go is to buy a microphone board.     (SparkFun publishes the schematic to that one if you want to copy the circuit.)

Sara94alzate

Yes, I know the process of configuring the microphone with the Arduino.
The thing is I need recomendations about what microphone would works properly if I need to guarantee a 80KHz of sound signal. The purpuse is to make a digital noise cancelling project.

So, If you have idea of recomendations for components that I can or may use, please let me know!

DVDdoug

#3
Aug 16, 2018, 11:45 pm Last Edit: Aug 16, 2018, 11:58 pm by DVDdoug
Quote
if I need to guarantee a 80KHz
Is that a typo???    ...Most microphones are designed for the audio range.   

And, "nose cancellation" is going to be extra-tricky at 80kHz (because of the short wavelengths) .  It's tricky-enough in the audio range (especially if it's not built-into headphones), and noise cancellation is usually not done digitally.   


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Basically, "all it takes" to do noise cancellation is a microphone and an inverting amplifier (or you can simply invert the speaker connections).   With the speaker making an inverted soundwave, the soundwaves cancel in the air.    With headphones, the microphone can be near the ear so it's picking-up the same sound as the ear (compensated for the sound-loss through the headphone housing).   With the microphone on the outside of the headphone housing, it can pick-up the original noise without picking-up the inverted sound from the speaker.

You can demonstrate the effect by reversing the connections to one stereo speaker.    You'll notice that most of the bass gets canceled.   The higher frequencies are not as completely canceled because you get phase differences with the shorter wavelengths (so the two are not exactly 180 degrees out of phase).   As you move around you'll hear different frequencies getting canceled which creates a weird "spacey/phasey" effect.    The effect is more dramatic (nd you get better cancelation) with mono recordings (where the left & right are identical).   

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