Abstract: A “sound system” is provided for outputting a notification sound easy for a specific user to hear within a range in which other users are not bothered. A notification sound output from a notification sound source is output to a driver via a loudspeaker situated on headrest of the driver's seat after gain adjustment by a variable gain amplifier. Gain setter estimates power of noise at each seat based on noise collected by microphone, calculates gain for notification sound that makes notification sound larger than noise at the driver's seat and makes notification sound smaller than noise at a specific seat by using a first transfer function of notification sound from loudspeaker to the user on the driver's seat and a second transfer function of notification sound from loudspeaker to the user on the specific seat, which are previously determined, and sets the gain in the variable gain amplifier.

Abstract: An acoustic system and an in-vehicle communication support system that increase the audible sound reproduction level of a parametric loudspeaker while mitigating disadvantages of ultrasonic radiation are provided. An ultrasonic wave amplitude-modulated with audible sound, emitted from a parametric loudspeaker enter an audible sound collector with a high directivity. Of incident ultrasonic wave and incident audible sound self-demodulated from the ultrasonic wave, the audible sound collector attenuates the ultrasonic wave, and reflects the audible sound to be collected at a position near the user. The audible sound collector can be composed of: a reflector having a reflecting surface formed of a paraboloid of revolution; and a sound absorber for absorbing an ultrasonic wave. The sound absorber can be composed of a sound absorbing material made of a phononic crystal, or of resonance tubes.

Abstract: A “sound system” is provided for outputting a notification sound easy for a specific user to hear within a range in which other users are not bothered. A notification sound output from a notification sound source is output to a driver via a loudspeaker situated on headrest of the driver's seat after gain adjustment by a variable gain amplifier. Gain setter estimates power of noise at each seat based on noise collected by microphone, calculates gain for notification sound that makes notification sound larger than noise at the driver's seat and makes notification sound smaller than noise at a specific seat by using a first transfer function of notification sound from loudspeaker to the user on the driver's seat and a second transfer function of notification sound from loudspeaker to the user on the specific seat, which are previously determined, and sets the gain in the variable gain amplifier.