Acoustic gasket and sealing guidelines

AN4427

10/19

DocID025705 Rev 1

Starting from these preliminary results, it is possible to state that geometry placed on top of

the microphone cavity produces a resonance effect. The above results can be summarized

in two basics conclusions:

1.

Firstly the resonance frequency moves lower and higher in the frequency domain,

respectively increasing or decreasing the length of the gasket.

2.

Conversely, the resonance frequency moves lower and higher in the frequency

domain, respectively decreasing or increasing the radius of the gasket.

Hence, if the gasket designer want to keep the frequency response flat as much as

possible, the first recommendation is to keep the gasket short and wide.

The following simulations are aimed to further investigate the dependence of the resonance

frequency, increasing the complexity of the geometry. The figures below represent the

simulated geometries and the respective results.

Figure 7. Simulated complex geometries

Table 2. Resonance peak vs. tube radius

Tube radius (µm)

Resonance frequency (Hz)

2.00E-04

20600

3.00E-04

26900

4.00E-04

31000

5.00E-04

33700