Method to enhance the low-frequency perception from a parametric array loudspeaker
Furi Andi Karnapi, Yew Hin Liew, Kelvin Lee, Woon Seng Gan · The Journal of the Acoustical Society of America · 2001
Human auditory system does not perceive the sound signal of all frequencies with equal loudness. Based on equal loudness curves, it is known that a low-frequency signal needs to be produced with a higher-power level to have the same loudness as the middle frequency part. There are two ways to overcome this problem; either boosting the power of the low-frequency part or utilizing the psychoacoustics effect called the missing fundamental. There are many works which have been done utilizing psychoacoustics to enhance the low-frequency perception of audio signal. These works are implemented to normal audio systems. Normal audio systems are comprised of a loudspeaker as the audio reproduction end. It is proposed to implement the low-frequency enhancement to a parametric array loudspeaker. The use of a parametric array loudspeaker to generate highly directional audible signal has been reported in several literatures. However, this audible signal lacks low-frequency content. One of the reasons is the relatively low-power level produced by the existing parametric array. By utilizing the nonlinearity property of the air itself, it is proposed to psychoacoustically enhance the perception of the low-frequency part.