Factors Affecting the TEOAEs


The following list refers to variables effecting significantly the amplitude of the TEOAE response.


  • Gender and ear differences: A number of studies on neonatal and adult subjects have reported that TEOAE recordings from females tend to show larger amplitudes and a more extensive TEOAE bandwidth. This evidence verifies previous data (McFadden: Sex differences in the auditory system Developmental Neuropsychology, 1998) reporting gender differences in the auditory system. The initial assumption that the TEOAE differences were the product of the diverse dimensions between the auditory structures of males and females, have been challenged by new evidence which shows that TEOAE differences exist even between heterosexual and homosexual subjects. An alternative hypothesis which might elucidate these differences would be to consider the role of hormones (estrogen in particular) on the functional status of the OHCs (see an early paper of Wharton JA, Church GT. Influence of menopause on the auditory brainstem response. Audiology 1990).
           Ear differences have been reported from the early studies on TEOAEs (See papers by Probst et al and Bonfils et al of the late 80s).The different TEOAE characteristics from the left and the right ear gave rise to the term hearing asymmetry.

  • The aging process: As aging processes affect the functional status and the distribution (effective number) of OHCs and IHCs, it is not surprising that aging affects the characteristics of the TEOAEs. It should be noted though that the most pronounced effects are generated by the alteration of the structures of the middle ear than the inner ear.

  • Genetic Factors: With the advances in the area of genetics it becomes more clear that a number of genetic factors expressed as variations of genes localized in various sub-structures of the organ of Corti are responsible for a large number of OAE dysfunction, which is also expressed as hearing impairment. Genetic factors , such as the ones we cluster together in well-identified syndromes, obviously affect not only TEOAEs but DPOAEs and SOAEs. Considering the noted gene-variations between races (for example Caucasian vs African) it is very probable that racial backgrounds might express different TEOAE characteristics, but there is no information in the literature for such studies.