Intensity-difference limens for very brief Gaussian-shaped tones at 500 Hz and 6.5 kHz
Lance Nizami, Walt Jesteadt · The Journal of the Acoustical Society of America · 2002
The curve of intensity-difference limen (DL) versus level shows a midlevel hump for 6.5-kHz tones having 5-ms cosine-squared ramps and a 26-ms plateau [Carlyon and Moore, J. Acoust. Soc. Am. 76, 1369–1376 (1984)]. DLs were presently obtained for that tone, as well as for 6.5-kHz tones having Gaussian envelopes, for five subjects. Pedestal levels covered 30- to 90-dB SPL and equivalent rectangular durations D were 0.314, 0.627, 1.25, 2.51, 10.03, and 20.1 ms, where D is the Gaussian-envelope duration divided by 3.19. The DLs for the tone of Carlyon and Moore (D∼30) show a midlevel hump smaller than found earlier. The hump grows noticeably with smaller D (i.e., the Gaussian-shaped tones), reaching 7 dB for D=0.627. The peak drops, however, for D=0.314, causing the curve of DL versus duration to peak for D=0.627 for tone levels of 40–60 dB SPL. DLs were also obtained from seven subjects for 500-Hz tones of 30–90 dB SPL for D’s of 1.25, 2.51, 5.02, and 10.03 ms. A midlevel hump at D’s of 1.25 and 2.51 gives way to a near-miss at D’s of 5.02 and 10.03. A mid-duration peak is seen at D=5.02 for levels of 30–60 dB SPL.