Dr. William Hartmann

Dr. William Hartmann, center, with a string quartet wired for a new recording technique. From left are Takeshi Abo, first violin; Karel Taulbee, second violin; Jan Wea Yoo, viola; and Mary Williams, cello.

In a talk presented at the 2 November 1999 meeting of the Acoustical Society of America in Columbus, OH, William Hartmann described and demonstrated a new method of sound recording and reproduction called "Local Performance Recording/Reproduction (LPR/R)." In his demonstration, he applied the technique to a Mozart string quartet. In a fundamental departure from traditional multichannel recording techniques, Hartmann isolated each instrument on its own two channels of an eight-channel digital recorder using two contact transducers per instrument.

He then experimented with different mixes of the two channels and different speaker con figurations for each instrument. With speaker radiation patterns similar to the particular violin, viola, or cello, and placements arranged as the musicians originally sat, the result sounds as if a live quartet were playing---the room acoustics were those of the listening environment and not those of the recording environment.

The LPR/R technique requires a minimum of one recorded channel and one transducer in the listening environment for each source in the ensemble. Application to string quartets is a natural since technically it works well, there is a vast and wonderful literature for string quartets, and there are many performers and devoted fans of string quartets. Conventional two-channel distribution of sound, via stereo broadcasting or compact discs or tape, is inadequate for LPR/R. The LPR/R technique depends on new technology (not far off) for multichannel distribution.

This talk was reported in the New York Times on November 16 and the article is available at website nytimes.com in the technology archive free article section as "A New Dimension in Recorded Music" by James Glanz. The November issue of Physics Today includes a related article by Hartmann on the localization of sound by human listeners.

You can learn more about Bill's research at http://www.pa.msu.edu/acoustics/