Physikalische Fragen und Gesichtspunkte bei der diagnostischen Geräusch-Verdeckungsmessung am Ohr

Since the important investigations of H. Fletcher and W. A. Munson the measurement of masking gains more and more importance, especially for the identification of disturbances of the inner ear.

A method of measurement of noise masking is shown in the course of which the different regions of the basilar membrane can be treated independently. The noise spectrum which is used has an outline figure lying symmetrically to the masked frequency. It can be shifted in octave steps along the frequency scale like the usual audiometer frequencies (c-scale), the outline figure remaining preserved. The procedure may be used for recording audiograms either with or without help of masking. For the recordings in the auditory sphere, fatigue plays an important part. The association between masking and fatigue is shown by means of displacements of thresholds, recorded shortly after the noise-treatment of the ear, i. e. in the transitional stage immediately after the treatment. This transition period has been made as short as possible (shorter than the time of equilibration). Displacements of thresholds, which correspond to the masking figures are given as a result, obviously these displacements are rests of masking.

Their influence on the recordings of the recruitment, especially on monaural measurement must not be neglected. This influence expresses itself in anomalous curvature of the increase of loudness on the measurement of masking with growing sound intensity. By this a recruitment is simulated. This is shown by examples.

These mistakes can be avoided or reduced by quick steps of measurement or by uniformity, i. e. mechanization of the measurement.