Wideband acoustic energy studies of pulmonary airways.

The impulse response of the pulmonary system has been measured by exciting the system with wideband acoustic noise introduced through the mouth. The transmitted sound is detected using microphones placed on the patient's back at appropriate locations. A specially designed analog correlator is used to obtain the impulse response of the pulmonary system through cross-correlation techniques. Uniquely characteristic responses have been obtained from smoking and nonsmoking patient groups.