Compensation methods of sound quality for a car-audio equalizer

When listening to music in a vehicle, its sound quality is disrupted by noise of the vehicle. In order to find the best method to compensate for the deterioration in sound quality, psychoacoustical experiments were conducted to evaluate the following four methods for designing the frequency characteristics of a car audio equalizer: simple amplification, non-linear amplification, narrow-band loudness compensation, and masked frequency spectrum compensation. As a result, narrow-band loudness compensation method was regarded as the best method.