Messersmith Jessica J, Patra Harisadhan, Jesteadt Walt
Center for Hearing Research, Boys Town National Research Hospital, 555 North 30th Street, Omaha, Nebraska 68131, USA.
J Acoust Soc Am. 2010 Nov;128(5):2973-87. doi: 10.1121/1.3488671.
It is often assumed that listeners detect an increment in the intensity of a pure tone by detecting an increase in the energy falling within the critical band centered on the signal frequency. A noise masker can be used to limit the use of signal energy falling outside of the critical band, but facets of the noise may impact increment detection beyond this intended purpose. The current study evaluated the impact of envelope fluctuation in a noise masker on thresholds for detection of an increment. Thresholds were obtained for detection of an increment in the intensity of a 0.25- or 4-kHz pedestal in quiet and in the presence of noise of varying bandwidth. Results indicate that thresholds for detection of an increment in the intensity of a pure tone increase with increasing bandwidth for an on-frequency noise masker, but are unchanged by an off-frequency noise masker. Neither a model that includes a modulation-filter-bank analysis of envelope modulation nor a model based on discrimination of spectral patterns can account for all aspects of the observed data.
人们通常认为，听者通过检测落在以信号频率为中心的临界带宽内的能量增加来检测纯音强度的增量。可以使用噪声掩蔽器来限制对落在临界带宽之外的信号能量的利用，但噪声的某些方面可能会对增量检测产生超出此预期目的的影响。当前的研究评估了噪声掩蔽器中的包络波动对增量检测阈值的影响。获得了在安静环境中以及存在不同带宽噪声的情况下，检测0.25 kHz或4 kHz基音强度增量的阈值。结果表明，对于同频噪声掩蔽器，纯音强度增量检测的阈值随带宽增加而增加，但对于异频噪声掩蔽器则保持不变。既包括包络调制的调制滤波器组分析的模型，也基于频谱模式辨别模型，都无法解释观测数据的所有方面。
