The listening approach that uses a parametric array loudspeaker system on a mobile phone is proposed, and the acoustic characteristics of a mobile-phone-size super-directional loudspeaker prototype are reported. The prototype has two sets of parametric loudspeakers that emit narrow ultrasonic beams that are demodulated into audible frequencies by the nonlinearity of air. Using an ultrasonic carrier wave amplitude-modulated by audible frequency, we realize audible sound pressures above 70dBSPL at the distance of 50cm, and also confirm the high directivity of the sound field. With the small-size super-directional loudspeaker, it is possible to provide a personal sound field for hands-free playback in mobile environments.
Authors:
Nakashima, Yusuke; Ohya, Tomoyuki; Yoshimura, Takeshi
Affiliation:
NTT DoCoMo, Inc.
AES Convention:
118 (May 2005)
Paper Number:
6521
Publication Date:
May 1, 2005
Subject:
Loudspeakers & Microphones
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