Hi
I am trying to set up an experiment on acoustic resonance and I am having a bit of trouble. What I am trying to do is to is make a circuit with one speaker that sends out a pulse into a closed cavity and the sound wave reflects off the wall of the cavity back to the speaker, then when the speaker feels the sound wave it immediately send out another pulse, reflecting the wave and reinforcing it at the same time. Is this something the Arduino could do?
A rough analogy of the idea if this helps, would be similar to bouncing a basketball. The speaker being the hand, the sound wave is the ball, cavity being the floor.
If I understand correctly, it will be no problem and is similar to how ultrasonic movement detectors are interfaced to an Arduino.
You'll need some discrete components as well to interface to the loud speaker. An arduino pin probably will not directly drive the speaker for sending the initial pulse and will probably not be sensitive enough to detect the returning pulse.
You'd simply send a pulse, wait for the speaker to stabilise, then enable the pulse detector function and wait for the returning pulse.
Then send your reinforcing pulse. You may get some interesting audio feedback effects.
Thanks for the reply
So far what I have done is hooked the speaker up to a small pre amp then send that signal to an amplifier, no issues here, where I hit a snag is when I try separate the incoming pulse to the pre amp from the out going pulse from the amp. As you can tell I’m not well versed in any of this so that’s why I’m here. I am open to try what ever
Also maybe resonance is maybe the wrong term. To start the speaker in motion I am planning to either tap the cavity or possibly play a note or a tone next to it, then the circuit can take over from there
Thanks
A computer (with it's soundcard of course) will be of a lot more use than an Arduino.
Typically you'd use a speaker & microphone with a sweep tone or white or pink noise. With a sweep you know the frequency, and with noise you have to analyze the frequency spectrum.
An impulse can also work. Again you have to analyze the spectrum.
[u]Here[/u] is a website about measuring room resonance that might give you some ideas.
Hammy
Not really looking to measure the frequency
I am wondering if something like a diplexer may work for this?
I just want this speaker set up to act as a reflector that adds energy as it reflects.
I think the cavity itself would determine the frequency.
The speaker would be a trigger and an output
cuck_schumer:
Hammy
Not really looking to measure the frequency
I am wondering if something like a diplexer may work for this?
I just want this speaker set up to act as a reflector that adds energy as it reflects.
I think the cavity itself would determine the frequency.
The speaker would be a trigger and an output
Your project will only work when the PHASE of the audio from the speaker is identical to the PHASE of the returning echo. Concentrate on this. Or determine when the voltages from each actually ADD together to create a sine wave with the RMS voltage being a maximum. A microphone, amplifier and AC voltmeter might work as you vary the frequency to the speaker.
Paul
Update: I may have found a solution, I am going to try a low voltage analog multiplexer switch between my out put and input. When the out put sends a positive voltage to the speaker it will first go thru the multiplexer and turn off the pre amp input. This should separate the 2 circuits so all the coupling between the 2 is done in the cavity with sound wave, there are a few more details to work out but they are fairly easy, thanks everyone for the input. I can post back with results if anyone is interested
cuck_schumer:
Update: I may have found a solution, I am going to try a low voltage analog multiplexer switch between my out put and input. When the out put sends a positive voltage to the speaker it will first go thru the multiplexer and turn off the pre amp input. This should separate the 2 circuits so all the coupling between the 2 is done in the cavity with sound wave, there are a few more details to work out but they are fairly easy, thanks everyone for the input. I can post back with results if anyone is interested
You must have one special speaker. All I have ever seen run on AC audio signals. A DC signal will only move the speaker cone in a single direction, then must allow the cone to spring back in time for the next pulse. Real speakers use AC so the cone is powered out and in.
Paul