and with various numbers of people occupying its seats, and found that the body of an average person decreased reverberation time by about as much as six seat cushions. Once the measurements were taken and before morning arrived, everything was quickly replaced in both lecture halls, in order to be ready for classes the next day. Sabine was able to determine, through the experiments, that a definitive relationship exists between the quality of the acoustics, the size of the chamber, and the amount of absorption surface present. He formally defined the reverberation time, which is still the most important characteristic currently in use for gauging the acoustical quality of a room, as number of seconds required for the intensity of the sound to drop from the starting level, by an amount of 60 dB (decibels). His formula is where T = the reverberation time V = the room volume A = the effective absorption area By studying various rooms judged acoustically optimal for their intended uses, Sabine determined that acoustically appropriate concert halls had reverberation times of 2-2.25 seconds (with shorter reverberation times, a music hall seems too "dry" to the listener), while optimal lecture hall acoustics featured reverberation times of slightly under 1 second. Regarding the Fogg Museum lecture room, Sabine noted that a spoken word remained audible for about 5.5 seconds, or about an additional 12-15 words if the speaker continued talking. Listeners thus contended with a very high degree of resonance and echo. Sabine's work was continued by his cousin Paul Earls Sabine at the Riverbank Laboratories from 1919. Using what he discovered, Sabine deployed sound absorbing materials throughout the Fogg Lecture Hall to cut its reverberation time and reduce the "echo effect." This accomplishment cemented Wallace Sabine's career, and led to his hiring as the acoustical consultant for Boston's Symphony Hall, the first concert hall to be designed using quantitative acoustics. His acoustic design was successful and Symphony Hall is generally considered one of the best symphony halls in the world. The unit of sound absorption, the Sabin, was named in his honor. Personal life Sabine had a wife and two daughters. Death Sabine died on January 11, 1919, at his home in Boston, Massachusetts. See also Akoustolith Acoustics Wallace Clement Sabine Medal of the Acoustical Society of America References Further reading Reverberation and the Art of Architectural Acoustics Emily Thompson, The soundscape of modernity :