<groan>
Not 'wikipedia' again. The purveyor of all truths. I'd prefer to read
quotes from more authoritative sources.

Tire noise isn't what destroys hearing, it is higher-frequency noise.
dBa is the std. by which all things important seem to be measured today.

If one needs super hi-fidelity music in a van, better run some trailer
tires, lots of sound deadener material everywhere, new seals on all the
windows, airfoils around the front window rubbers....or better yet just
pull over for those passages you just can't miss.

Sorry, next time I won't mention my experience.

Rocket J Squirrel wrote:
> dBa scale? The majority of the road/tires/suspension-borne noise is
> bass. The dBa filter attenuates bass and treble, it's down 20dB at 100Hz
> where 80% of the transmitted noise is. A-weighting is only useful for
> low-level sound measurements.
>
> "...A-weighting, though originally intended only for the measurement of
> low-level sounds (around 40 phon), is now commonly used for the
> measurement of environmental noise and industrial noise ... although it
> is badly suited for these purposes, being only applicable to low levels
> so that it tends to devalue the effects of low frequency noise in
> particular."
>
> (http://en.wikipedia.org/wiki/A-weighting)