In normal-hearing listeners, rippled-spectrum discrimination was psychophysically investigated in both silence and with a simultaneous masker background using the following two paradigms: measuring the ripple density resolution with the phase-reversal test and measuring the ripple-shift threshold with the ripple-shift test. The 0.5-oct wide signal was centered on 2 kHz, the signal levels were 50 and 80 dB SPL, and the masker levels varied from 30 to 100 dB SPL. The baseline ripple density resolutions were 8.7 oct-1 and 8.6 oct-1 for the 50-dB and 80-dB signals, respectively. The baseline ripple shift thresholds were 0.015 oct and 0.018 oct for the 50-dB and 80-dB signals, respectively. The maskers were 0.5-oct noises centered on 2 kHz (on-frequency) or 0.75 to 1.25 oct below the signal (off-frequency maskers). The effects of the maskers were as follows: (i) both on- and low-frequency maskers reduced the ripple density resolution and increased the ripple shift thresholds, (ii) the masker levels at threshold (the ripple density resolution decrease down to 3 oct–1 or ripple shift threshold increased up to 0.1 oct) increased with increasing frequency spacing between the signal and masker, (iii) the masker levels at threshold were higher for the 80-dB signal than for the 50-dB signal, and (iv) the difference between the masker levels at threshold for the 50-dB and 80-dB signals decreased with increasing frequency spacing between the masker and signal. Within the 30-dB (from 50 to 80 dB SPL) signal level, the growth of the masker level at threshold was 27.8 dB for the on-frequency masker and 9 dB for the low-frequency masker. It is assumed that the difference between the on- and low-frequency masking of the rippled-spectrum discrimination reflects the cochlear compressive non-linearity. With this assumption, the compression was 0.3 dB/dB.
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机译:在正常听力的听众中,使用以下两个范式在无声和同时掩蔽背景下从心理上研究了波纹频谱的辨别力:使用相反转测试测量波纹密度分辨率,以及使用波纹测试测量波纹位移阈值移位测试。 0.5八分之一宽的信号以2 kHz为中心,信号电平为50和80 dB SPL,掩蔽电平从30 dB到100 dB SPL不等。对于50 dB和80 dB的信号,基线纹波密度分辨率分别为8.7 oct -1 sup>和8.6 oct -1 sup>。 50 dB和80 dB信号的基准纹波漂移阈值分别为0.015 oct和0.018 oct。掩蔽器是0.5 oct的噪声,中心位于2 kHz(同频),或者比信号低0.75至1.25 oct(离频掩蔽)。掩蔽器的影响如下:(i)低频掩蔽器和低频掩蔽器均降低了纹波密度分辨率并提高了纹波偏移阈值;(ii)处于阈值的掩蔽器电平(纹波密度分辨率降低至3 oct) –1 sup>或波动偏移阈值增加到0.1 oct)随着信号和掩蔽器之间的频率间隔增加而增加;(iii)对于80 dB信号,阈值处的掩蔽器电平高于50 dB -dB信号;以及(iv)50 dB和80 dB信号的阈值处的掩蔽电平之间的差异随掩蔽信号和信号之间的频率间隔的增加而减小。在30 dB(从50到80 dB SPL)信号电平范围内,同频掩蔽器在阈值处的掩蔽器电平增长为27.8 dB,低频掩蔽器为9 dB。假定脉动频谱鉴别的高频和低频掩蔽之间的差异反映了耳蜗压缩非线性。在此假设下,压缩率为0.3 dB / dB。
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