Fast and accurate threshold method for determination of temporary threshold shifts

When the hearing is exposed to loud sound a temporary shift of the absolute threshold is induced (temporary threshold shift, TTS). The time- and frequency-dependence of a such shift can be used to assess the relationship between the different parameters of an exposure to sound with loud levels and the potential for acquiring a permanent hearing damage. When TTS is to be assessed experimentally, a fast and accurate psychometric method is required to determine the instantaneous threshold, while the threshold changes in time and returns to its pre-exposure level. In this project the Békésy audiometric method is evaluated as an adequate method to determine a threshold shift caused by sounds of high level. This was done through listening test using the threshold method with different types of probe stimuli (single events, bursts signals, continuous stimuli, pure tones, narrow frequency bands and frequency modulated tones). The results showed that a narrow band noise signal used as a single event stimuli gave the best efficiency for the fixed frequency Békésy audiometric method. (STVF framework programme. In 2002 with the participation of Morten Lydolf)