Maybe the idiom is slightly off, but losing a gasket ended up costing us a few weeks of production time when we were building the Ubi. Microphone placement is finicky business when it comes to voice pick up and even the slightest misalignment of the microphone or too much spacing can create a detrimental effect on speech recognition.
There are at least two types of issues that come up with the placement of microphones on hardware. The first has to do with the cavity in which the microphone is placed. If the cavity is too narrow or deep, you can get an effect called attenuation or Helmholtz Resonance. Think of a jug instrument.
The second issue is acoustic isolation. This can be isolation from a speaker that’s outputting sound from the same device or mechanical isolation of the microphone from vibrations on the device.
To help with both, most microphone placements will have a silicon rubber gasket or seal that will hold the microphone in place and allow for a snug fit within a case. These need to be properly designed around the industrial design of the device and require quite a bit of testing to ensure proper performance.
In the case of the Ubi, the performance was night and day after a gasket was used to secure the mic. However, they’re small and while they were specially designed for our device, they shipped in a ziplock bag. This bag was not conspicuous and at one point, it disappeared. We had a factory line ready to go except one lousy missing bag halted everything.
We were able to use the downtime to make improvements to the Ubi but it was critical to use the gaskets to improve performance.