Hearing damage without soundproofing

[wayner]

I've followed many builds since 2000. Bare interiors were very popular so that is what I did with my RSR replica.

In mine, I have always found it necessary to drive with ear plugs. I thought a quitter muffle right be the solution to comfortable driving, but I discovered something very interesting. While the exhaust sound is too loud to be comfortable, the biggest noise spikes on my meter were caused by the plastic rear racing suspension bushings squeaking!

The two needle images at peak were:
low peak = exhaust
high peak = squeak

Here are my readings from a recent drive (this was with my meter sitting on the front passenger seat in a non-soundproofed early 911).
(actually, while I say non sound-proofed, I actually used quite a bit of dynomat on the rear seat and shelf area. This had little to no affect as you can see)

[RSBob]

My wife is a doctor of Audiology AuD and I know exactly what she would say since we have been together for several millennia Sustained exposure to high levels of noise without protection 100+ dB will lead to hearing imparement and eventual loss. Bikers are some of her most profitable patients. Also exposure to high spikes of brief noise (think gun shots) will also take you down the same path. Another big group of patients are cops with lots of range time and maybe not great protection several years back. If your ears hurt or your ears ring you are on the road to hearing aids Prolonged exposure to either without protection can lead to hearing loss. Btw. Good hearing aids start at $4k.

[RSTarga]

so switch to rubber bushings and you'll be good to go.

[al lkosmal]

what!!!!!!!!!

[wayner]

I'll be switching to more modern greasable poly bronze bushings instead of the old track only plastic bushings.

Also on my list is a quieter exhaust.

But, the interior is such a boom box even with the dynomat that I will be taking further steps to make it more comfortable. As is, its great when I have my helmet on but not so great on the street.

[KNS]

wayner,

You're on the right track but dynomat alone isn't going to cut it. You can make these car quieter (well, not exactly Lexus...). My '84 is pretty darn quiet for it's age but I've added about 20 something pounds of material (equal to a few gallons of gas) to get there. It was well worth it.

Do a search on Closed Cell Foam and Mass Loaded Vinyl (CCV and MLV).

[wayner]

I absolutely agree with that.

I hope others who have been proponents of dynomat read this. Aside from a bit of it in some strategic places, Dynomat is waste of weight.

Closed cell foam and vinyl are next on the layering list.