discussion / Acoustics  / 20 May 2024

Mounting Electret Microphone

Hi all,

I'm curious to hear experiences/thoughts on mounting microphones in potted instrument housings that will receive a fair amount of movement and vibration. This is for an animal-borne acoustic monitoring sensor, with a 2mm thick housing and an EC mic (https://www.digikey.com/en/products/detail/db-unlimited/MW042502-1/13243482).

The diameter of the mic is 4mm, but the opening in the rubber holder is only 2mm. So one option I'm considering is to have a chamfered, 2mm diameter through-hole in the housing and a ~4.3mm diameter circular lip on the inside into which the microphone would be slotted. Then pot the internal components and secure a piece of foam in the through hole to reduce wind noise. Another option would be to have a ~4.1mm through-hole into which the microphone would tightly fit, and a lip on the outside for the wind noise reduction material. But I'm wary of this design without a better form of securing the microphone.

Do one of these plans sound more reasonable? Would the depth/angle of the chamfer make a difference to sound attenuation? Any other design considerations this brings to mind?

Thanks!




If you search Digikey for a 'strain relief' you should be able to find a rubber grommet that will hold that mic without any additional machining. A blob of silicone will adhesive and  waterproof, I always like stuff to do at least two things. It's also vibration reducing on the mic. You may want to either 'shotgun' mic by putting it at the end of a tube, that will block a lot of ambient also. Unless it whistles like a bottle in the wind, that might be a problem later lol. Or use a dish as a focus.