Developmental changes in tympanometry: a case study.

The use of 226 Hz tympanometry in neonates and infants has been controversial due to the large number of false negative responses for middle ear pathology. A review of the literature highlights several anatomical differences between this population and that of the adult, which is not recognized during interpretation of their tympanograms. The aim of the study was to document tympanometric changes in a single child using 226 Hz, 1000 Hz and sweep frequency probe tones until she was 6.5 months old. Both 226 Hz and 1000 Hz tympanograms show a maturational change in middle ear resonance from a mass to a stiffness-dominated system, which was corroborated by sweep frequency probe tones. It is suggested that high-frequency probe tones were able to increase test sensitivity to the mechanics of the middle ear when it was mass-dominated, as in this infant. Due to the large intersubject variability reported in the literature, it is recommended that both high and conventional probe tone tympanograms are performed in infants under 6 months of age to increase diagnostic accuracy. Middle ear resonance can also be determined for each individual enabling more appropriate selection of probe tones for Y, B and G tympanometry.

A pilot investigation of high-frequency audiometry in obscure auditory dysfunction (OAD) patients.

The diagnosis of obscure auditory dysfunction (OAD) has been an elusive one, based primarily upon reports of poor speech perception in noise by the patient. Basic audiometric testing reveals hearing within normal threshold limits and it is thought that there may, in part be some subtle psychoacoustic and/or central auditory deficits causing this phenomenon. The use of high-frequency audiometry (HFA) as a test of subclinical cochlear damage has been well documented, especially to monitor the early effects of noise exposure and ototoxic drugs. However, it has not been used in the diagnosis of OAD patients. This study examines the use of HFA as an aid to the understanding of OAD pathophysiology. HFA was conducted on nine OAD subjects, each matched to two controls. Results indicate an elevated threshold amongst all frequencies (10-20 kHz) in OAD patients with significant differences occurring at 10, 14, 16 and 20 kHz. It could be postulated that OAD in fact, is the product of an ultra-high-frequency hearing impairment and its psychoacoustic sequelae. Furthermore, HFA may be a useful inclusion in a diagnostic test battery for OAD status. However, the degree to which it can be used may be limited due to the large intersubject variability in HFA thresholds in the normal population. It is suggested that further investigations into the ultra-high-frequency hearing abilities of OAD patients should be completed in the future.

Training to meet the needs of the communicatively impaired population of South Africa: a project of the University of the Witwatersrand.

At a time when South Africa is in the throes of transition, ideologies in the educational, medical, economic and social spheres are being redefined and redirected. The field of speech pathology and audiology is no exception. The Department of Speech Pathology and Audiology, University of the Witwatersrand has acknowledged an urgent need to address the requirements of a multilingual and multicultural South Africa and extend training beyond the white middle-class population. It is the responsibility of the training institutions to redirect the objectives of their curricula in order to meet these needs. This paper describes the changes introduced by the Department. These include teaching of community work principles and primary health care to the speech and hearing therapist, and the training of personnel for an alternative form of service, such as the community speech and hearing worker (CSHW) and the community-based rehabilitation worker (CBRW).

A new look at cochlear mechanics.

The spectacular discovery of otoacoustic emissions has led to a plethora of cochlear mechanic models, all attempting to explain the active, nonlinear processing of the cochlea suggested by these recordable responses. These hypothetical proposals have been largely based on animal experimentations, mathematically-based theorems, and observations in simulated environments. None have been irrevocably validated although there is much circumstantial evidence expounding their feasibility. Advances in electron microscopy, mechanical engineering, histological examination techniques together with the technology enabling us to measure these emissions, have radically altered the current views on the assumptions of auditory mechanics. This paper briefly contrasts the previously established cochlear theories proposed by doyens such as Helmholtz (1857) and von Békésy (1936) with current perspectives advanced by cell biologists and biophysicists. However, the exact nature of cochlear processing still remains a mystery. As numerous chasms of knowledge about audition are being filled, so even more questions are posed in a seemingly eternal quest for the answer!