Sound Transmission Through the Human Body
During the 200 years that have elapsed since Laennec’s invention of the stethoscope and publication of his groundbreaking book Treatise on the Diagnosis of the Diseases of the Lungs and Heart, the stethoscope has become an irreplaceable diagnostic tool. Yet for most of that time, doctors have simply been taught to associate certain sounds with the absence or presence of certain diseases. Only during the last 50 years or so have scientists attempted to discover the underlying mechanisms of lung sound production and transmission. This has turned out to be a difficult task as the sounds had not been accurately described in acoustic terms and locating the sources in a noisy, complex, living biologic system was often daunting and difficult to prove. At least as hard has been the task of tracking the paths taken by lung sounds to the site where they are detected. This is due to the constant background noise, probable multiple sound paths, different media, and the intense filtering by the inflated lung of higher-frequency components. Yet there has been progress, and some of the findings may lead to new diagnostic techniques. This chapter reviews the more significant discoveries about how sound travels through the respiratory system.
- 1.Laennec RTH (1819) De l’Auscultation Médiate ou Traité du Diagnostic des Maladies des Poumons et du Coeur (On mediate auscultation or treatise on the diagnosis of the diseases of the lungs and heart). Brosson and Chaudé, ParisGoogle Scholar
- 28.Anon. https://en.wikipedia.org/wiki/Nyquist-Shannon_sampling_theorem. Wikipedia. Accessed 9 July 2016