November 27, 2006--A new type of stethoscope enables doctors to hear the sounds of the body in extremely loud situations, such as during the transportation of wounded soldiers in Blackhawk helicopters. Using ultrasound technology, the kind used to generate images of internal organs, muscles and unborn fetuses, the new stethoscope design will be presented later this week at the Fourth Joint Meeting of the Acoustical Society of American and the Acoustical Society of Japan, which will be held at the Sheraton Waikiki and Royal Hawaiian Hotels in Honolulu, Hawaii.
Researchers at Active Signal Technologies, Inc., of Linthicum Heights, Md., in collaboration with the U.S. Army Aeromedical Research Laboratory (USAARL) in Fort Rucker, Ala., have developed an ultrasound stethoscope that is nearly impervious to loud noise and is capable of making accurate readings at noise levels up to 120 decibels, similar to the volume experienced at the front row of a rock concert.
Current acoustic stethoscope technology picks up and amplifies vibrations that let doctors hear the heart and lungs. These models become difficult to use effectively around 80 decibels, a noise level comparable to an alarm clock or a busy city street. When noise levels reach 90 decibels, these types of stethoscopes are rendered useless. Modern electronic stethoscopes have raised the maximum tolerable noise level to 90 decibels to 95 decibels by replacing the ear pieces with loudspeaker inserts that provide a better seal with the ear canal and replacing the tubing with electrical cables that do not pick up acoustic noise.
The challenge to build a better stethoscope originated from the Army's Small Business Innovation Research program. For soldiers wounded in combat, the first hour after sustaining an injury is known as the "critical hour," when diagnoses and emergency treatment must take place to give them the best chance of recovery. These soldiers are often transported by helicopter,
Contact: Turner Brinton
American Institute of Physics