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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
    Commented Apr 10, 2019 at 22:53
  • $\begingroup$ Very interesting! I would try - if possible - to change the distance of the grill to the speaker. If that changes the measured frequency range of boost or attenuation the area between speaker and grill and the grill seem to have some kind of wave-guide function. It would also effect directivity. So measuring at an angle of say 45° with and without grill could be interesting, too. Sound radiation might be concentrated in the center which results in a "boost" in measurement. $\endgroup$
    – vattes
    Commented Sep 11, 2022 at 8:41

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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
    Commented Apr 12, 2019 at 18:03
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    $\begingroup$ The fundamental resonance is a half wavelength. So more like 17 mm. $\endgroup$ Commented Apr 13, 2019 at 4:55

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