Instrumentation for studies of cochlear mechanics: from von Békésy forward.

Georg von Békésy designed the instruments needed for his research. He also created physical models of the cochlea allowing him to manipulate the parameters (such as volume elasticity) that could be involved in controlling traveling waves. This review is about the specific devices that he used to study the motion of the basilar membrane thus allowing the analysis that lead to his Nobel Prize Award. The review moves forward in time mentioning the subsequent use of von Békésy's methods and later technologies important for motion studies of the organ of Corti. Some of the seminal findings and the controversies of cochlear mechanics are mentioned in relation to the technical developments.

Békésy's contributions to our present understanding of sound conduction to the inner ear.

In our daily lives we hear airborne sounds that travel primarily through the external and middle ear to the cochlear sensory epithelium. We also hear sounds that travel to the cochlea via a second sound-conduction route, bone conduction. This second pathway is excited by vibrations of the head and body that result from substrate vibrations, direct application of vibrational stimuli to the head or body, or vibrations induced by airborne sound. The sensation of bone-conducted sound is affected by the presence of the external and middle ear, but is not completely dependent upon their function. Measurements of the differential sensitivity of patients to airborne sound and direct vibration of the head are part of the routine battery of clinical tests used to separate conductive and sensorineural hearing losses. Georg von Békésy designed a careful set of experiments and pioneered many measurement techniques on human cadaver temporal bones, in physical models, and in human subjects to elucidate the basic mechanisms of air- and bone-conducted sound. Looking back one marvels at the sheer number of experiments he performed on sound conduction, mostly by himself without the aid of students or research associates. Békésy's work had a profound impact on the field of middle-ear mechanics and bone conduction fifty years ago when he received his Nobel Prize. Today many of Békésy's ideas continue to be investigated and extended, some have been supported by new evidence, some have been refuted, while others remain to be tested.

Contributions of von Békésy to psychoacoustics.

This paper reviews the contributions of von Békésy to psychoacoustics, comparing his findings and interpretations to those that have emerged since his work. The areas covered include the perception of pitch for pure tones and complex tones, the effect of frequency on the apparent location of pure tones, estimation of the velocity of the traveling wave on the basilar membrane using judgments of lateralization, and the relative loudness of monaural and diotic sounds. While subsequent research has failed to replicate some of his findings, other findings have stood the test of time. There is no doubt that von Békésy made very substantial contributions to psychoacoustic research.

A historical perspective on digital hearing AIDS: how digital technology has changed modern hearing AIDS.

This article provides the author's perspective on the development of digital hearing aids and how digital signal processing approaches have led to changes in hearing aid design. Major landmarks in the evolution of digital technology are identified, and their impact on the development of digital hearing aids is discussed. Differences between analog and digital approaches to signal processing in hearing aids are identified.

Audiological medicine in the UK: the historical perspective of its role and scope.

A medical, as opposed to a surgical, specialty which was to be entrusted with the investigation, care and management of patients with hearing and balance disorders was established in the UK in 1975. This medical specialty was termed 'audiological medicine' and its specialists, 'audiological physicians'. The relationship of the audiological physician to the ear, nose and throat surgeon is analogous to that between the neurologist and the neurosurgeon, or to that between the cardiologist and the cardiac surgeon. The audiological physician's role needs to be distinguished also from that of the audiologist. An audiologist is a scientist (or technician). (In the UK, science is firmly established as an integral and autonomous discipline within British health-care systems.) The role and scope of the audiological physician is clarified. Audiological physicians are concerned primarily with patients suffering from disorders of auditory communication, equilibrium and spatial disorientation, i.e. 'deaf and dizzy' patients.