Methods of recording and analysing cough sounds

Efforts have been directed to evolve a computerized system for acquisition and multi-dimensional analysis of the cough sound. The system consists of a PC-AT486 computer with an ADC board having 12 bit resolution. The audio cough sound is acquired using a sensitive miniature microphone at a sampling rate of 8 kHz in the computer and simultaneously recorded in real time using a digital audio tape recorder which also serves as a back up. Analysis of the cough sound is done in time and frequency domains using the digitized data which provide numerical values for key parameters like cough counts, bouts, their intensity and latency. In addition, the duration of each event and cough patterns provide a unique tool which allows objective evaluation of antitussive and expectorant drugs. Both on-line and off-line checks ensure error-free performance over long periods of time. The entire system has been evaluated for sensitivity, accuracy, precision and reliability. Successful use of this system in clinical studies has established what perhaps is the first integrated approach for the objective evaluation of cough.