Temporary threshold shift after exposure to a narrow‐band noise, frequency‐modulated tones, continuously variable frequency tones and a pure tone

Temporary threshold shift after exposure to four stimulating sounds were measured by automatic audiometry for three subjects with normal hearing. Stimulating sounds were (1) a pure tone, (2) continuously variable frequency tones between 1250 and 1750 Hz, (3) frequency‐modulated tones centered at 1500 Hz with a frequency deviation of ± 250 Hz and a modulation rate of 25 per s, (4) a narrow‐band noise with a bandwidth of 1250–1750 Hz. Subjects were exposed to stimulating sound through an earphone at the intensity of 110 dB SPL and duration of 10 min. Temporary threshold shift was measured for frequencies between 1000 and 8000 Hz beginning at 5 s after cessation of the stimulating sound. Results indicated that the greatest shift was observed at a frequency 2000 Hz by a pure tone stimulation and the least shift by a narrow‐band noise. Effects of continuously variable frequency tones and frequency‐modulated tones were intermediate. These findings were compared and discussed with temporary threshold shift follo...