Page 47 - January 2006

Echoes from Minneapolis
world. This suggests that the problem of hospital noise is universal, and that noise control techniques might also be expected to be applicable broadly.
There are only a couple of noise control studies in hos- pitals and most of these focus on administrative controls such as asking staff to speak softly and to close patient room doors. Historically administrative noise controls have had very limited effectiveness because of the need for constant attention. We recently took a different approach to the problem and studied the impact of adding sound absorbing material to a hospital unit. Hospitals tend to have hard floors and walls, and increasingly they are choosing not to use acoustical ceiling tiles because of con- cern that bacteria will become trapped in the small holes found in such tiles. We created sound absorbing panels from fabric-covered construction fiberglass (a very good sound absorber). The fabric was a special anti-bacterial material. The results of placing these tiles on the ceilings were very encouraging. The reverberation time in the hall- ways was cut in half, meaning that noise died out much faster. We also saw a drop in the unit ambient noise, and most importantly, surveys of staff and patients indicated immediate awareness and approval of the change. The study was sufficiently successful in quieting the unit that
hospital leaders are now discussing how to provide similar noise relief throughout the hospital.
There is still much work to be done on quieting hos- pitals. For instance, while we are beginning to under- stand how loud the hospital environment is, we haven’t yet determined the significance of each of the major noise sources. Nor have we adequately studied tonal qualities of hospital noises that would let us better predict human reactions to them. However, it is reassuring to begin to have clear directions in which to move to address this series of important problems.
Jim West, is a Research Professor at Johns Hopkins University in the Department of Electrical and Computer Engineering. He retired as a Bell Laboratories Fellow, Lucent Technologies in 2001. He served as ASA president in 1998-99 and received the Silver Medal in Engineering Acoustics in 1995. He will be awarded the ASA Gold Medal in June 2006.
Ilene Busch-Vishniac is Professor of Engineering at Johns Hopkins University. She was ASA President in 2003-04, received the ASA Biennial Award in 1987 and the ASA Silver Medal in Engineering Acoustics in 2001.
Minneapolis skyline as seen from Loring Park near the Hilton. (Photo by Tom Rossing.)
Minneapolis near the Hilton. (Photo by Tom Rossing.)
Echoes 45