'loudness' is a term normally used to describe a function which increases the treble (high frequency) and bass (low frequency) content of the sound. Effectivelt you can do this by turning the bass and treble controls up!

It has no connection with dolby...and there are many forms of dolby which is a method of recording and playing back music to imporve it audible quality (or the number of chanels).

I dont know of any volvo units with a loudness function specifically, but you can get the same effect by boosting th bass and treble controls...

In fact it was aonly really ever a marketing tool (along with rumble and scratch filters) invented in the 1970's to try and impress people with the number of knobs on an amplifier....if anythign it LOWERS the quality of the sound as it adds distortion and curcuitry....

If you look at proper hi-fi amplifiers most dont even have tone controls....