ABSTRACT
This chapter considers heart and breath sounds, and the pathologies that can be diagnosed from them. It covers otoacoustic emissions (OAEs) and describes their potential importance in diagnosing hearing problems. There are many endogenous sources of acoustic energy that have diagnostic significance. These include, but are not limited to, heart sounds, the lungs, arteries, stomach and intestines, joints, and the inner ear. Stethoscopes and microphones respond to the sound waves that the vibrating skin radiates into the air. There are several types of microphones suitable for picking up air-coupled body sounds from the skin. These include capacitor microphones, piezoelectric microphones, and electret microphones. Microphones generally have a high-frequency response that is quite adequate for endogenous body sounds. The chapter examines the techniques used to make a time– frequency spectrogram (TFS). Almost all diseases of the lungs are characterized by certain classes of abnormal breath sounds.
