Question for Bonehead helmet users

[fl-mike]

Originally Posted by MK77

Most mic's for this application are what are referred to as "noise cancelling" which is a bit of a misnomer. More accurately they should be called "noise rejecting". Not sure what the specs of the mic in question are.

I'd be surprised if the mic 'muff' makes a big difference, at least not without impacting the quality of the speech pickup as well.

If the un-muffed mic is hitting its AOP, then the leather muff will drop the sensitivity back into the linear region by providing an overall attenuation.
If it is at the AOP then the speech will not be adding significantly to the overall saturated signal so you will also have issues with not enough dynamics for a good squelch break when speaking as well as poor quality speech. Of course, the leather muff reduces the overall dynamic range since the mic noise floor will not move, but we are well above that.

[MK77]

Originally Posted by fl-mike

If the un-muffed mic is hitting its AOP, then the leather muff will drop the sensitivity back into the linear region by providing an overall attenuation.
If it is at the AOP then the speech will not be adding significantly to the overall saturated signal so you will also have issues with not enough dynamics for a good squelch break when speaking as well as poor quality speech. Of course, the leather muff reduces the overall dynamic range since the mic noise floor will not move, but we are well above that.

For those not in the know, AOP = acoustic overload point or Max SPL capability. Basically, the sound pressure level at which the microphone being driven so hard that it is outputting a non-linear (distorted) signal.

Your point above is certainly viable, if the mic is being overdriven. My guess is that the mic's in question just have poor polar response or just too much low frequency response which is allowing a lot of diffuse noise to get in. Impossible to know without evaluating them.

[GlennBfromOz]

As another data point, in my also noisy Bonehead I tried the high-noise mic insert. The result is dramatically better voice quality, without the wind noise getting through. Mal (OP) and I proved the difference today by installing my mic in his helmet, with the same improvement noted. So this, for us, is the solution.

It seems there's a bit of variation in quality of the standard mic. Another member of our formation team sounds fine from his helmet, in his equally rowdy RV.

For reference, the original insert is a Pilot PA-7X, and the replacement is a PA-HNM. It also seems to be labelled PA-9EHN in some places.

Glenn