Does anyone know why there are three slots in the interior trim piece in the photo? (Having trouble with the photo upload.)

It is to the right of the steering wheel, right and a little down from the ignition.

I'm looking to place a microphone there for the new car stereo. Would like to know the purpose of those slots before I do.

I can't see anything behind that trim piece. Seems like you could put a microphone behind that piece since there are slots there must be a reason for the slots. Stock microphone are mounted in the headliner I believe.

Seems like near the steering wheel is better than the headliner for us shorter folk and when it's raining.

Trim Piece

1 Answer 1


I did a whole lot of work on automotive interior design including Heating Ventilation and Air Conditioning (HVAC) as well as microphone location testing for Cell phone integration.

  • That three slot opening in the trim panel? I'm guessing that's for an optional "Automatic Temperature Control" HVAC system. (I'm assuming in your car you set the temperature with a dial cool/warm to desired...) If your car had that option, there would be a temperature sensor behind that grill, with a small fan pulling in air from the vehicle interior for accurate temperature sampling.

  • Microphone location: I did a whole lot of testing here... The best place for a microphone audio clarity is directly in front of the person on the call. At one time we used the top of the steering wheel column for microphone location. That works great if the driver is using the phone hands free, terrible if anybody else in the car wants to speak. That steering wheel location can also pick up the sound of the steering wheel turning. The area at the headliner near the rear view mirror is a great choice, and that's where most manufacturers place the microphone.

  • And yes, using that grill on your vehicle would be a great choice for a microphone location. I'm also guessing you see some empty screw sockets on the back of that trim piece. Feel free to use 'em to mount your mic.

Note: I never realized how difficult microphone selections are these days... Electret Condenser Mic or MEMS mic?, Omnidirectional or directional? Noise cancellation or not? Lots of choices.. Good luck with it..

  • Wow! Thanks so much for the detail even before I got a photo uploaded. You are right that I have the base manual temperature control. Thanks much for the feedback on the microphone location too! I'm using the microphone that came with the new stereo so hopefully that is good enough but I'll keep in mind upgrades if need. I know hand held microphones have a foam cover. Have you ever seen one of those used for a car microphone?
    – joecap5
    May 21, 2020 at 1:15

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