Nelson D A, Freyman R L
J Acoust Soc Am. 1986 Mar;79(3):799-805. doi: 10.1121/1.393470.
Psychometric functions for pulsed pure-tone frequency discrimination were obtained from hearing-impaired listeners at frequencies with normal hearing and at frequencies with mild or moderate hearing losses. The general form of psychometric functions at hearing-impaired frequencies was found to be the same as at normal-hearing frequencies, i.e.,d' was linear with the frequency difference between tones, in Hz. For all but one psychometric function, the addition of an intercept term to the fitting equation did not account for significantly more variance than did the slope term alone. Therefore, it was concluded that psychometric functions for frequency discrimination can be adequately described with only one parameter: the slope of the psychometric function. Deficits in discrimination at hearing-loss frequencies were manifested by more gradual slopes of psychometric functions. Procedures for normalizing psychometric functions are presented, which facilitate comparisons of normal and impaired frequency discrimination data across studies and frequencies. Comparisons of dlf's (difference limen for frequency) obtained with adaptive and fixed procedures show a bias toward larger dlf's with adaptive procedures, but only at higher frequencies. A discussion of equal-interval and equal-ratio adaptive stepping rules indicates that an equal-ratio rule may be preferable.
针对听力受损的受试者，在听力正常的频率以及存在轻度或中度听力损失的频率上，获取了脉冲纯音频率辨别能力的心理测量函数。结果发现，在听力受损频率下心理测量函数的一般形式与听力正常频率下相同，即d'与音调之间以赫兹为单位的频率差呈线性关系。对于除一个心理测量函数之外的所有函数，在拟合方程中添加截距项并不能比仅使用斜率项解释更多的方差。因此，得出的结论是，频率辨别心理测量函数仅用一个参数就可以充分描述：心理测量函数的斜率。在听力损失频率下辨别能力的缺陷表现为心理测量函数的斜率更为平缓。文中介绍了使心理测量函数标准化的程序，这有助于跨研究和频率比较正常和受损频率辨别数据。通过自适应程序和固定程序获得的频率差别阈（dlf）的比较表明，自适应程序存在偏向于得出更大dlf的偏差，但仅在较高频率下如此。对等间隔和等比例自适应步进规则的讨论表明，等比例规则可能更可取。
