Fowler C G, Mikami C M
Veterans Administration Medical Center, Long Beach, CA 90822.
Electroencephalogr Clin Neurophysiol. 1992 Mar-Apr;84(2):157-63. doi: 10.1016/0168-5597(92)90020-c.
The masking level difference (MLD) is a psychoacoustic phenomenon derived from the subtraction of S pi No thresholds (signals pi radians out of phase and noise in phase at the two ears) from SoNo thresholds (signals and noise in phase at the two ears). The purpose of this study was to determine if the MLD derived from the late components (P1, N1, P2, N2) of the auditory evoked potentials was a physiological correlate of the behavioral MLD. Subjects were 15 young adults with normal hearing. Comparisons were made between behavioral and late potential thresholds to 500 Hz stimuli in So and S pi conditions in quiet, and to 500 Hz stimuli in SoNo and S pi No conditions in narrow band (50 Hz) and wide band (600 Hz) noise. No significant differences were seen for behavioral or late-potential thresholds to So and S pi conditions. The S pi No thresholds was significantly lower than the SoNo threshold, yielding an MLD for both the behavioral and physiological responses. The magnitudes of both the behavioral and late-potential MLD were larger with the narrow band noise than with the wide band noise. Evidence, therefore, is provided that the late-potential MLD reflects similar processes as are responsible for the behavioral MLD.
掩蔽级差（MLD）是一种心理声学现象，它是通过从双耳同相的信号加噪声（SoNo）阈值中减去双耳异相的信号加噪声（SπNo）阈值（信号异相π弧度且噪声同相）而得出的。本研究的目的是确定从听觉诱发电位的晚期成分（P1、N1、P2、N2）得出的MLD是否是行为学MLD的生理相关指标。研究对象为15名听力正常的年轻成年人。对安静环境中So和Sπ条件下500Hz刺激的行为阈值和晚期电位阈值，以及窄带（50Hz）和宽带（600Hz）噪声中SoNo和SπNo条件下500Hz刺激的行为阈值和晚期电位阈值进行了比较。对于So和Sπ条件下的行为或晚期电位阈值，未观察到显著差异。SπNo阈值显著低于SoNo阈值，从而产生了行为反应和生理反应的MLD。窄带噪声下行为学和晚期电位MLD的幅度均大于宽带噪声下的幅度。因此，有证据表明晚期电位MLD反映了与行为学MLD相同的过程。
