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Canalographic evaluation of the external ear canal in dogs.

Canalography was performed to measure the diameter of the horizontal ear canal and to assess the clinical relevance of the measurements in identifying abnormalities of the ear canal. The diameter of the proximal and distal end of the annular cartilage in the horizontal ear canal was measured using canalography in 222 ears. The tympanic membrane could not be visualized with otoscopic examination in 70 ears even after ear cleansing. These canals were classified as being stenotic. The diameter of the proximal annular cartilage in the stenotic canals ranged from 0.8 to 3.1 mm (mean = 2.6 +/- 0.8 mm). The proximal annular cartilage was consistently smaller in diameter than the distal annular cartilage. The ratio between the diameter of the proximal and distal annular cartilage varied between dogs. In stenotic ear canals (70 ears) the ratio was less than 0.65. Total ear canal ablations and histopathological analysis were performed in 70 ear canals classified as stenotic after canalography. Hyperplasia of the epidermal layer was found in 56 stenotic canals. Stenosis of the canal due to otitis externa was found in the other 14 canals. Three canals with severe otitis externa were also diagnosed with canalography as having a ruptured tympanic membrane. The results suggest that canalography can be used to measure the diameter of the horizontal ear canal and to assess whether or not the tympanic membrane is ruptured prior to conservative or surgical therapy.

Animals↗
PubMed1990

The auditory periphery of the ferret. II: The spectral transformations of the external ear and their implications for sound localization.

In the previous paper the directional response characteristics of the ferret auditory periphery were examined. In this study further measurements of the spectral transfer functions (STFs) of the auditory periphery were obtained at locations close to the tympanic membrane. There was considerable variation in the STFs recorded from different animals and between recordings made at each end of the auditory canal in the same animal. However, calculation of the so called "location dependency function" demonstrated that changes in the location of the stimulus produced the same pattern of changes in the STFs in all recordings. Changes in the spectral transformation for azimuth locations in the ipsilateral auditory field were examined by calculating the horizon STF. The gain transformations of frequencies below 20 kHz were found to be asymmetrical about the interaural axis so that maximum gain was obtained for anterior stimulus locations. In contrast, the maximum gain for frequencies above 20 kHz was obtained for stimulus locations about the interaural axis, and movement of the stimulus location into either the anterior or posterior fields produced symmetrical reductions in gain. These changes were related to the directional properties of the periphery examined in the previous paper [S. Carlile, J. Acoust. Soc. Am. 88, 2180-2195 (1990)]. The spatial resolution of the monaural information provided by the peripheral STFs is dependent on the rate of change of the transformations as a function of azimuthal displacement of the stimulus location. This was examined by calculating the unsigned first spatial derivative for each frequency in the horizon STF.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1999

Virtual localization improved by scaling nonindividualized external-ear transfer functions in frequency.

This study examined virtual sound localization in three conditions that differed according to the directional transfer functions (DTFs) that were used to synthesize the virtual targets. The own-ear and other-ear conditions used DTFs measured from listeners' own ears and those measured from other subjects, respectively. The scaled-ear condition employed other-ear DTFs that were scaled in frequency to minimize the mismatch between spectral features in the listener's and the other subject's DTFs. All measures of localization error typically were lowest in the own-ear condition. In other-ear conditions, all error measures tended to increase in proportion to the inter-subject differences in DTFs. When spectral features in an other-ear set of DTFs fell systematically lower in frequency than in a listener's own DTFs, low frontal targets typically were reported as low in the rear, and high rear targets were reported as high in front. When spectral features in a set of DTFs fell systematically higher in frequency than in a listener's own DTFs, elevation judgements showed an upward bias. In the scaled-ear condition, all measures of performance tended to improve relative to the other-ear condition. In the majority of cases, frequency scaling more than halved the penalty for use of another subject's DTFs.

Adult↗
PubMed1984

External ear canal exostosis and aquatic sports.

Many reports suppose that the development of aural exostosis depends on the action of an irritative stimulus like frequent and repeated cold water contact. This survey studies the incidence of this lesion in a group of 433 athletes practicing aquatic sports on a highly competitive level. Among these, water activities like sailing and deep-sea diving, which up to now were never considered, were also studied. 32 exostoses were found to affect 12 subjects monolaterally and 20 subjects bilaterally. Not one of a control group of 476 athletes was found to be affected by aural exostosis. For each athlete in this study the following parameters are considered: age and sex, type of sport, total amount of hours spent in water contact, aural pathology history and otoscopic findings. The authors suggest the existence of facilitating factors other than total water contact time, as shown by the absence of a precise correlation between this parameter and the presence of the aural hyperostotic lesion.

Diving↗
PubMed1986

Soft-wall reconstruction of the posterior external ear canal wall.

A simple method of reconstructing a previously removed posterior ear canal with an autogenous, bilaminar membrane is described. The resulting air-filled mastoid cavity is an anatomic extension of the middle ear cleft and is separated from the ear canal by a functional barrier that is continuous with the tympanic membrane. The acoustic characteristics of an associated tympanoplasty are not significantly altered, and many of the problems that are associated with an exteriorized cavity are avoided. In contradistinction to other methods of mastoid obliteration or reconstruction, the semitransparent nature of the soft canal wall allows inspection of the underlying cavity for residual or recurrent disease. The technique can be used to repair either a newly created cavity or a previous radical (or modified radical) mastoidectomy defect. The functional results of thirty ears reconstructed in this fashion are detailed. A variable amount of soft-wall retraction was noted postoperatively in 47% of the ears; however, the long-term functional results in these cases remain satisfactory.

Connective Tissue↗