    A paper [6] describing the results of the first prototype, as
    well as a live demonstration, were presented at the 105th
    Convention of the Audio Engineering Society in September,
    1998, and received a standing ovation.  While the parametric
    array itself is not patentable, MIT has applied for patents on
    key aspects of the technology which make it a practical
    device.

    This directivity plot of a prototype clearly illustrates the
    extreme narrowness of the beam. (Published in [6]).  During
    the summer of 1998, we compared distortion of prior devices
    with our  prototype.  Note that distortion has been reduced
    nearly to that of a traditional loudspeaker.  (Published in
    [6]).

    Since then, development has been remarkably productive, with
    engineering and mathematical advances resulting in more sound
    output, better sound quality, and reliable performance.

    "Everything you do with light, you can now do with sound."TM

    References:

    [1]  Westervelt, P. J., J. Acoust. Soc. America, v35 535-537
         (1963)
    [2]  Bennett, M. B., and Blackstock, D. T., J. Acoust.  Soc.
         America, v57, 562-568 (1975)
    [3]  Yoneyama, M., et al., J. Acoust. Soc. America, v73,
         1532-1536 (1983)
    [4]  Blackstock, D. T., J. Acoust. Soc. America, v102 3106(A)
         (1997) link
    [5]  Berktay, H. O., J. Sound Vib., v2, 435-461 (1965)
    [6]  Pompei, F. J., J. Audio Eng. Soc., v47, 726-731 (1999)
         (originally in Proc. 105th AES Conv., Preprint 4853 (1998) )

    About the Inventor:

    Beginning his career in acoustics at 16 while in high school,
    starting as the first high school co-op and becoming the
    youngest engineer at Bose Corporation, Frank Joseph Pompei
    continued working part-time and summers for Bose while earning
    a degree in Electrical Engineering with an Electronic Arts
    Minor from Rensselaer Polytechnic Institute.  Recognizing the
    importance and underutilization of spatialized sound, he
    decided to pursue research in psychoacoustics and application
    of auditory localization at Northwestern University, earning a
    Master's degree.  Acutely aware of the limitations of
    traditional loudspeakers, he had the idea of using ultrasound
    as an acoustic projector, and is now developing such a device
    at the MIT Media Lab, continuing his education in pursuit of a
    Ph.D.
                                  -98-