Mechanical Vibration Transmitted thru Cable 3

[MDGroup]

We are making in-ear microphone systems and are having a problem with our current electrical cable that runs from your ear down to your radio/phone.

Our microphone picks up your voice thru the very small vibrations in your ear. Due to the low signal, we have to use an extremely sensitive microphone in our ear piece. However, the mic also picks up any mechanical noise that transfers through the cable. Basically, if you rub your fingers on the cable, it transfers that noise directly up the cable to the microphone and interrupts transmission. Even if you just move your head and the cable drags against your shirt, it is very audible. It is behaving like a string tied between 2 tin cans.

Note, this is mechanical noise (not electrical noise) that we need to address.

Are there any cables out there designed to specifically address this issue? Something that limits the transmission of mechanical noise thru the cable.

Will different jacket materials transmit different amounts of noise? (pvc, silicone, ...)

Is there anything that can be attached to the cable to act as an isolator or damper? Something we can install on the cable close to the mic that wont let the vibration pass thru?

Any suggestions are greatly appreciated.
Thanks.

 

[btrueblood]

Clip a strain relief to the user's earlobe?

 

[GregLocock]

You need some measurements in my opinion. Mount the mic on a shaker and measure its sensitivity to vibration.

Then you know what the target is

Now you need to know how much your cable vibrates axially under typical excitations, devise an experiment to assess that.
Since you probably want to jump to a solution:

You could clip a mass to the cable near the ear

you could coat the cable in teflon to reduce the chance of it snagging

you could coat the cable with foam to reduce impact noise.

you could make a little coil of cable near the ear to act as a spring.

However, in the real world of sensitive measurements, we tape our cables as firmly as possible to the surroundings,

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Strong]

Google: reduce cable microphonics
Walt

 

[MDGroup]

Thanks for all the input.

I agree the best way would be to clip the cable to the user in several places to reduce how much the cable can move, but we also need a solution if the user doesn't want to do that.

We are having a rubber ear hanger made to loop the cable around at the users ear. This will hold the cable securely, and hopefully the large mass will dampen the vibrations.

Walt, thanks for the search words. That is exactly what I am looking for; I just didn't know what to look for. Looks like there will be some good info there.