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I am planning on making a musical instrument where I require the conversion of vibration of a material to voltage. The idea is to make a percussion instrument where I hit a plate made of a certain type of material. Based on the different areas on which I hit the plate, the vibrations will be different and after converting the vibrations to voltage, I will take the FFT of the signals to differentiate the different areas on which I hit the material and map it to produce a particular sound. I know that piezoelectric sensor is a material which converts pressure to voltage but I am not sure if it will be robust enough. Is there any alternative I can use?

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    \$\begingroup\$ So if it makes a noise then a microphone... \$\endgroup\$ – Solar Mike May 18 '18 at 10:31
  • \$\begingroup\$ Accelerometry and strain gauges come to mind. \$\endgroup\$ – Vicente Cunha May 18 '18 at 10:37
  • \$\begingroup\$ @SolarMike I haven't chosen a material yet but it must not make too much noise or otherwise it will interfere with the sound of the musical instrument. \$\endgroup\$ – user3147192 May 18 '18 at 10:39
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    \$\begingroup\$ Use the microphone to measure the noise the plate makes - any other sensor except optical will cause a change ... but what about a laser? Measure the change of position... \$\endgroup\$ – Solar Mike May 18 '18 at 10:43
  • \$\begingroup\$ Magnetic sensors are a possibility as are piezoelectric. As well as the various technologies of microphones (condenser, electret, MEMS digital microphones, to mention a few). Have you done research into how other musical instruments pick up vibrations? Electric guitar pickups generally use magnetic pickups, acoustic can use a mix of piezo and microphone because they want to pick up the strings and the wood. \$\endgroup\$ – Spehro Pefhany May 18 '18 at 12:21
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What you plan seems very difficult to achieve. You are talking about different vibrations when you hit different places. What do you think will be different? Sound loudness level or sound frequency? If you go with frequency, then a microphone would be your device. Measuring sound loudness differences in a hard material is very hard to achieve, because it is a very tiny difference.

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  • \$\begingroup\$ I plan to do both. My concern is mostly with the frequency. For the loudness, I will take the rms value of the input signal to the microcontroller and normalise it. Then I will multiply the normalised value with the audio samples which have to be played. \$\endgroup\$ – user3147192 May 18 '18 at 10:43
  • \$\begingroup\$ Ok, so you need a Microphone and you need to measure the frequency and amplitude of the Mic. voltage. \$\endgroup\$ – Stefan Wyss May 18 '18 at 10:53
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It seems you would like to correlate position of impact on the striking surface to frequency. The mic followed by appropriate signal processing will produce the time, frequency, and amplitude. A second sensor system is needed to determine point of impact.

As you mentioned, piezo might work, but I suspect this would require an array of sensors rather than a single sensor. Another thought might be to surround your striking surface with an array based on optical touch sensor technology such as this and shown in the illustration below.

enter image description here

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