A gap-based level-discrimination test detects acoustic neurinoma early

Evidence

In audiology, level discrimination is normally evaluated by the use of the SISI test and the Liischer/Zwislocki test. These tests use modulated tones or direct increases in level without pauses between the presentations. Another test which is effective in the early detection of acoustic neurinoma uses 200-ms tone pulses with a relatively long Gaussian rise/decay time of 20 ms. In contrast with the two tests mentioned, there are silent intervals of 200-ms duration between the tones to be compared. The measurements are performed at 6 frequencies in octave steps between 0.25 and 8 kHz. The data are measured at a level of 30 dB above hearing threshold, and the patient has to judge whether the loudness of the consecutive tone pulses is the same or different. The level difference of the alternating tones can be increased in 0.25 dB steps. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1897

While the normally hearing subjects show a level-difference threshold near 1.5 dB, results for the patients with acoustic neurinoma are about a factor of 3 larger, i.e. 4.5 dB. The medians range from 4 to 4.7 dB and the interquartile ranges do not overlap at all. Because there were 52 patients for the data set, it is clear that there is a distinct increase in the level-difference threshold for patients with acoustic neurinoma. The finding that 49 out of 52 patients with proven acoustic neurinoma showed distinctly increased level-difference threshold emphasizes the attractiveness of this method. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1898

Categorization

• XREF: The design contrast - discrete pulses with 200 ms silent gaps versus continuous modulations - parallels the temporal-resolution findings central to the reader’s interest.
• corroborated: 2 independent passages support this claim — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1897; Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1898