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I am measuring the frequency response(5KHz - 20KHz) of a small dynamic speaker driver with the stainless steel grill and without the grill.

Without the grill the response is what I would expect. However; when I have the grill ON; I was expecting some sort of attenuation across the board. However; instead of attenuation I am seeing a boost between 10KHz - 20KHz region.

Below 10KHz the response is similar to without grill.

Is there some sort of interaction of signal onto the speaker grill causing this behavior ?

I am trying to understand; what could potentially cause this boost ?

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  • $\begingroup$ Have you thought about resonance? Worth looking at the grill's resonant frequencies $\endgroup$ – Rory Alsop Apr 10 at 22:53
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With a speed of sound of 340 m/s you can expect to have resonces with any spatially periodic structure with a period a half integer multiple of that of the sound. E.g. 10kHz would be a fundamental frequency for a 15 mm periodic structure. There is also resonances for the speed of sound in the grill material as well as the air gap.

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  • $\begingroup$ Thanks. How did you come up with the the resonance number of 15mm ? The wavelength of 10KHz is 34.3mm. Is there a way we can model the resonance of speed of sound + air gap ? $\endgroup$ – user26543 Apr 12 at 18:03
  • $\begingroup$ The fundamental resonance is a half wavelength. So more like 17 mm. $\endgroup$ – Paul Childs Apr 13 at 4:55

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