hissing sound inside on acceleration-1999

[johnholl]

On my wife's car, [recently puchased used] I seem to be hearing a vacuum leak sound, under acceleration only, inside the car eminating from the passengers-side.although none of the climate control levers seem to be vacuum actuated. car seems to be running great. HVAC okay. AC works Fine. The engine is quiet from the outside: Noisy inside, with the windows rolled up, A\C and radio off.

Is this normal interior noise for the 1.8L engine? My mom's Corolla: The 1.6L engine seems to make less noise, on the inside that is.