Compensation for Road Noise in Automotive Entertainment Systems

Vehicle operation noise, even in the quietest cars, produces high sound pressure levels (SPL) at very low frequencies. This noise masks desired signals in and above this frequency range. A blind subjective test, using ten listeners, was undertaken to determine a frequency response equalization curve that would compensate for this noise under specific but realistic conditions. Starting with a 4 dB full-band level increase, an average of 40 listener responses showed a gentle rise in bass reaching an additional 4 dB at 50 Hz.