Re: "El Cheapo" dummy heads? (William L Martens )

Subject: Re: "El Cheapo" dummy heads?
From:    William L Martens  <wlm(at)U-AIZU.AC.JP>
Date:    Fri, 6 Jul 2001 09:12:27 +0900

I've made some great sounding recordings using a bowling ball as a cheap replacement for more expensive dummy heads, and the system offers some advantages over dummy heads with pinnae. Interesting in this regard is: G. Theile (1991) "On the naturalness of two-channel stereo sound," JAES, 39(10), 761-767. No elevation, but good spatial imagery that supports binaural echo suppression (an advantage when recording at or transmitting from cocktail parties). Perhaps some have had the opportunity to hear the Neumann KFM 100 spherical-surface condenser microphone? I liked the sound, but I didn't buy one; instead I went to the local bowling alley and asked them to use their custom drilling machine to make three holes in my bowling ball, but not for three fingers. Rather I gave them a diagram showing two microphone holes at plus and minus 100 deg, and a larger hole at the bottom for inserting a microphone stand. With microphones the parts totaled to around $200: Small bowling ball with custom drilling at $80 2 SONY ECM-7140 Miniature Condenser Microphones at $60 The directional response measurements are not so different from those Dick Duda and I made using a bowling ball with a flush-mounted probe tube, results that were published in: R. O. Duda & W. L. Martens (1998) "Range dependence of the response of an ideal rigid sphere", JASA, 105(5), 3048-3058. The very dense bowling ball preforms better than less dense spheres (e.g., hollow plastic ones), which can added coloration due to unwanted internal sound signal propagation and resonances. Most important here is that most agree: the bowling ball can capture and produce good auditory spatial imagery. -- William L. Martens, Ph.D. Associate Professor Multimedia Systems Lab URL: University of Aizu TEL: [+81](242)37-2791 Aizu-Wakamatsu 965-8580, Japan FAX: [+81](242)37-2731 ------------------------------

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