The suprathreshold acoustic reflex responses of forty two ears affected by sensorineural hearing loss of cochlear origin and fifty-eight ears demonstrating normal hearing, were recorded by means of an electro-acoustic impedance meter and attached X-Y recorder. The recordings were done in ascending and descending fashion, at successively increasing and decreasing 5dB intensity levels from 90-120-90 dB HL respectively, for the individual pure-tone frequencies of 500, 1 000, 2 000 and 4 000 Hz. The contralateral mode of measurement was employed. Analysis of these recordings indicated that the acoustic reflex responses could be differentiated into five characteristic patterns of growth, which could be depicted upon a continuum of peaked, peaked-rounded, rounded, rounded-flat, and flat shapes. The peaked and peaked-rounded patterns were found to predominate at all four pure-tone frequencies in the normal ears, while the rounded-fiat and flat patterns were found to predominate only at the higher pure-tone frequencies of 2 000 and 4 000 Hz in the ears affected by sensorineural hearing loss. This latter relationship was also able to be applied to two disorders of the loudness functio— loudness recruitment and hyperacusis. It was concluded that the flattened acoustic reflex patterns at the higher pure-tone frequencies constituted a potential diagnostic cue related to the differential diagnosis of sensorineural hearing loss, and to disorders of the loudness function.
Significance of 125 Hz Pure-Tone Thresholds for Dizzy Patients with Low Frequency Sensorineural Hearing Loss
