A questionnaire was administered to 528 tinnitus patients to obtain data on their reactions to tinnitus. Results include a discussion of: (a) population characteristics, (b) perceptual characteristics, (c) the impact of tinnitus on daily life, and (d) etiology. Significant gender differences are also discussed. Tinnitus was not an occasional phenomenon, but was present for more than 26 days per month in 74% of the patients. Other important findings about tinnitus include: (a) Hearing levels at 1000 and 4000 Hz were less than or equal to 25 dB HL for 18% of the tinnitus patients, which suggests that some patients had normal hearing or mild hearing losses; (b) the prevalence of tinnitus in patients with noise-induced hearing loss (NIHL) was 30% for males and only 3% for females; (c) about 25% of the patients reported tinnitus severity had increased since tinnitus onset; (d) the effects of tinnitus were more severe in patients who reported tinnitus as their primary complaint and in patients diagnosed as having Meniere's syndrome tinnitus; and (e) some patients reported that noise exacerbated their tinnitus, whereas others reported that a quiet background exacerbated their tinnitus.

Characterization of Tinnitus by Tinnitus Patients

This paper provides an overview of changes in the perception of sound that result from cochlear damage. It starts with a brief introduction to the physiology of the cochlea, emphasizing the role of the "active mechanism" and describing how cochlear function is altered by cochlear damage. Then the effects of cochlear damage on various aspects of perception are described, including absolute sensitivity, frequency selectivity, loudness perception and intensity discrimination, temporal resolution, temporal integration, pitch perception and frequency discrimination, and sound localization and other aspects of binaural and spatial hearing. The possible role of each of these aspects of auditory perception in the ability to understand speech in quiet and in noise is discussed and evaluated. It is concluded that, for losses up to about 45 dB, audibility is the single most important factor. However, for greater losses, poor discrimination of suprathreshold (audible) stimuli is also of major importance. The final section of the paper describes applications of the findings to hearing aid design. It is concluded that linear amplification can be of only limited benefit in compensating for the effects of cochlear damage. Hearing aids incorporating compression can help to compensate for the effects of reduced dynamic range. Digital signal processing to enhance spectral contrast may be of some help in compensating for the effects of reduced frequency selectivity.

Perceptual Consequences of Cochlear Hearing Loss and their Implications for the Design of Hearing Aids

How does subjective magnitude, S. increase as physical magnitude or intensity, I, increases? Direct ratings (magnitude scales; partition or category scales) can be fitted by the power function, S = aIb, in which S equals I raised to a power or exponent, b, and multiplied by a measure constant, a. The exponent is typically about twice as large for the magnitude scale (Stevens) as for the corresponding partition or category scale, but the higher exponent may be explained by the overly expansive way people use numbers in making magnitude estimations. The partition or category scale and the adjusted (for the use of number) magnitude scale for a given modality or condition generally agree with the neurelectric scale and the summated just noticeable difference (jnd) scale. A unified psychophysical law is proposed in which each jnd has the same subjective magnitude for a given modality or condition, subjective magnitude increases as approximately a power function of physical magnitude with the exponent ranging from near 0 to 1 (compressive function), and subjective magnitude depends primarily on peripheral sensory processes, that is, no nonlinear central transformations occur. An undue reliance on Weber's law blinded Fechner to the fact that the true psychophysical scale is approximately a power function. Rejecting Weber's law, which is not valid, means that we no longer have to choose between letting the summated jnd scale be a logarithmic function (Fechner's law) and introducing a nonlinear central transformation to make it into a power function (Brentano–Ekman-Teghtsoonian's law). Fechner and Stevens erred equally about the true psychophysical power function, whose exponent lies halfway between that of Fechner (an exponent approaching zero) and that of Stevens. To be reconciled, Fechnerians must give up the assumptions that Webers law is valid and that the jnd has the same subjective magnitude across modalities and conditions; Stevensians must give up the assumption that the unadjusted (for the use of number) magnitude scale is a direct measure of subjective magnitude.

Reconciling Fechner and Stevens: toward a unified psychophysical law

A revised model of loudness perception applied to cochlear hearing loss.

Equal-loudness-level contours provide the foundation for theoretical and practical analyses of intensity-frequency characteristics of auditory systems. Since 1956 equal-loudness-level contours based on the free-field measurements of Robinson and Dadson [Br. J. Appl. Phys. 7, 166–181 (1956)] have been widely accepted. However, in 1987 some questions about the general applicability of these contours were published [H. Fastl and E. Zwicker, Fortschritte der Akustik, DAGA ’87, pp. 189–193 (1987)]. As a result, a new international effort to measure equal-loudness-level contours was undertaken. The present paper brings together the results of 12 studies starting in the mid-1980s to arrive at a new set of contours. The new contours estimated in this study are compared with four sets of classic contours taken from the available literature. The contours described by Fletcher and Munson [J. Acoust. Soc. Am. 5, 82–108 (1933)] exhibit some overall similarity to our proposed estimated contours in the mid-frequency range up to 60 phons. The contours described by Robinson and Dadson exhibit clear differences from the new contours. These differences are most pronounced below 500 Hz and the discrepancy is often as large as 14 dB.

Equal-loudness-level contours for pure tones.

An investigation of the relation among individual power-function exponents for 51 adults with normal hearing was undertaken. Three different psychophysical procedures were employed: absolute magnit...

Prediction of Individual Loudness Exponents from Cross-Modality Matching

Individual and group loudness relations were obtained at a frequency in the region of impaired hearing for 100 people, 98 with bilateral cochlear impairment. Slope distributions were determined from absolute magnitude estimation (AME) and absolute magnitude production (AMP) of loudness; they were also derived from cross‐modality matching (CMM) and AME of apparent length. With respect to both the means and the individual slope values, the two distributions closely agree. More than half of the measured deviations are less than 20%, with an overall average of −1.5%, meaning that transitivity is preserved for bilaterally impaired individuals. Moreover, over the stimulus range where cochlear impairment steepens the loudness function, both the group means and the individual slope values are clearly larger than in normal hearing. The results also show that, for groups of people with approximately similar losses, the standard deviation is a nearly constant proportion of the mean slope value giving a coefficient of variation of about 27% in normal and impaired hearing. This indicates, in accord with loudness matching, that the size of the slopes depends directly on the degree of hearing loss. The results disclose that loudness measurements obtained by magnitude scaling are able to reveal the operating characteristic of the ear for individuals.

Loudness relations for individuals and groups in normal and impaired hearing

The present article provides an analysis of loudness growth rates in normal and cochlear-impaired hearing for diverse groups with respect to age and backgrounds. Slopes are obtained from absolute magnitude estimation and magnitude production of loudness (measured values), and from cross-modality matching and absolute magnitude estimation of apparent length (predicted values). Consistent with an earlier study [R. P. Hellman and C. H. Meiselman, J. Acoust Soc. Am. 88, 2596-2606 (1990)], slopes calculated within the 15-30 dB stimulus range above the elevated threshold increase in size with the degree of hearing loss. The corresponding range of loudness values in normal hearing yields a slope near 0.60 independent of the threshold levels. This pattern of loudness growth holds for individuals and groups. But the intersubject variability of the slope is more labile, being larger across than within groups and larger for the measured slopes than for the predicted values. Determined from the predicted slopes, the coefficient of variation, sigma/m, is approximately constant in normal and impaired hearing ranging from 20%-27%. In contrast, sigma/m, obtained from the measured slopes, increases with the degree of hearing loss to a value of almost 50% for a 75-dB loss. The overall stability and systematics of the observed effects further demonstrate that the loudness-intensity relation can be specified with reasonable precision and accuracy from cross-modality matching.

Rate of loudness growth for pure tones in normal and impaired hearing

Loudness adaptation was measured for pure tones at 4, 12, 14, and 16 kHz. In three experiments, a total of 87 young listeners judged—by the method of successive magnitude estimation—the loudness of the tones over a 6‐min exposure period. Thresholds were measured by an adaptive 2IFC procedure. Although earlier measurements had shown that adaptation near threshold increases with frequency, these new data reveal that the increase is especially marked at higher sensation levels. Thus, at 40 dB SL, over a 6‐min period loudness declined by 18% at 4 kHz and by 94% at 16 kHz. Moreover, the 4‐kHz tone remained audible for all listeners throughout the 6‐min exposure period whereas the 16‐kHz tone became inaudible for two‐thirds of them by the end of the exposure period. Listeners with relatively low thresholds (<50 dB SPL) at 16 kHz showed much less adaptation at 14 kHz than at 16 kHz and much less than listeners with relatively high thresholds (≳50 dB SPL) at 16 kHz; this latter group showed strong adaptation at 14 kHz. The marked loudness adaptation of steady tones at very high frequencies and relatively high sensation levels is associated with a restricted spread of excitation in the auditory system resulting from the steep rise of the threshold curve at the highest audible frequencies.

Carol H. Meiselman

Papers

Prediction of Individual Loudness Exponents from Cross-Modality Matching

Loudness relations for individuals and groups in normal and impaired hearing

Rate of loudness growth for pure tones in normal and impaired hearing

Loudness adaptation at high frequencies.