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The Journal of General Psychology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/vgen20
Four Triggering Factors in Loudness Adaptation a
a
Ernest M. Weiler , Laurie Smith Gold , David E. a
Sandman & Joel S. Warm
b
a
Department of Communication Science & Disorders , University of Cincinnati , USA b
Department of Psychology , University of Cincinnati , USA Published online: 06 Jul 2010.
To cite this article: Ernest M. Weiler , Laurie Smith Gold , David E. Sandman & Joel S. Warm (1992) Four Triggering Factors in Loudness Adaptation, The Journal of General Psychology, 119:4, 325-334, DOI: 10.1080/00221309.1992.9921175 To link to this article: http://dx.doi.org/10.1080/00221309.1992.9921175
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The Journol of General Psychology, 119(4). 325-334
Downloaded by [York University Libraries] at 14:50 29 December 2014
Four Triggering Factors in Loudness Adaptation ERNEST M. WEILER LAURIE SMITH GOLD DAVID E. SANDMAN Department of Communication Science & Disorders University of Cincinnati
JOEL S. WARM
Department of Psychology University of Cincinnati
ABSTRACT. A factor analysis was used to determine whether induced loudness adaptation (Botte, Canevet, & Scharf, 1982; Scharf, 1983) and adaptation measured by Hood’s ( 1950) classic Simultaneous Dichotic Loudness Balance technique (SDLB) would cluster on the same factors. The two phenomena did not cluster on the same factors; thus, induced adaptation cannot replace SDLB adaptation. Four independent factors that trigger auditory adaptation were identified in the factor analysis.
HOOD’S MONUMENTAL STUDY (1950) has stimulated much research in the area of auditory adaptation. However, subsequent studies using a variety of techniques have resulted in conflicting conclusions. In Hood’s classic (1950) Simultaneous Dichotic Loudness Balance (SDLB) technique, one ear received a continuous, adapting tone of constant intensity while the other ear received an intermittent, adjustable comparison This article evolvedfrom a project conceived by Ernest M . Weiler and Laurie Smith Gold as part of Ms. Gold’s MA requirements; her laboratory skills were essential to the research. We wish to acknowledge the help of h u r a Kretschmer, Angel Dell‘aira, Kenneth Donnelly, Satish Venkatesan. Yea Wen Shiau. Bertram Scharf. and J. Derek Hood. Address correspondence to Ernest M . Weiler. Psychoacoustics Lahoratoy M.L. #379, Department of CommunicationScience & Disorders, University of Cincinnati, Cincinnati, OH 45221. 325
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tone. After several minutes of stimulation, the listener was to set the adjustable tone so that it would be as loud as he or she thought the adapting tone was. The listener set the adjustable tone so that it was much less intense than the adapting tone. The value of the dB decline in the comparison ear was considered to be the measure of monaural adaptation to the continuous tone. Bocca and Pestalozza ( I 959) and Stokinger and Studebaker ( 1968), among others, have challenged the validity of the SDLB procedure, suggesting that the time-based changes that occur with the use of the SDLB technique are due to interaural artifacts rather than the adaptation of the continuously stimulated ear. A number of researchers who used monaural techniques have answered this challenge by demonstrating adaptation effects that were comparable in magnitude to those found with the binaural SDLB procedure. For example, Weiler and Friedman (1973) and Weiler and (Friedman) Gross (1976) used a monaural heterophonic balance procedure that resulted in 22 dB of adaptation, the same amount Weiler, Loeb, and Alluisi (1972) found, using the SDLB. Davis and Weiler (1976) used a monaural reaction time technique and found that response slowed significantly, as would be expected with a decline in loudness. Moreover, Weiler, Sandman, and Pederson (1981) devised a monaural loudness-estimation technique with an ipsilateral loudness referent that demonstrated substantial loudness adaptation, as measured by magnitude estimates (MEs). These results were replicated by Canevet, Scharf, and Botte (1983). Botte, Canevet, and Scharf ( 1982) and Scharf (1983) tested the validity of the SDLB in still another way, using a procedure in which MEs, instead of the contralateral intermittent tone, were used to indicate the loudness of the continuous, adapting tone. Adaptation effectsoccurred when the functionally neutral intermittent tone was present, but not when it was absent. Botte et al. and Scharf attributed these adaptation effects, which they labeled induced adaptation, to an artifact of psychophysical contrast based on funneling (von Bekesy, 1958). Botte et al. and Scharf would have us believe that their results duplicate most or all of the effects that occur with the SDLB procedure, but the induced adaptation technique differs from the SDLB approach in two important ways: 1. Given the imprecision that exists when MEs of loudness are con-
verted to dB changes, the magnitude of the induced adaptation effects is considerably smaller than that of the adaptation effects obtained with the SDLB technique. 2. Using the induced adaptation technique eliminates adjustment in the comparison ear, and Mulligan, Goodman, Gleisner, and Faupel (1985) have demonstrated that adjusting the intensity of sound in one ear actively affects loudness in the other.
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In the present study, we used factor analysis to determine whether the results of the induced adaptation procedure explain those that are obtained with the SDLB technique. In factor analysis, correlations between measurements are used to group similar variables (Kachigan, 1982) that define the underlying dimensions, or factors, of behavior. If the adaptation measured by the SDLB technique is subsumed by that in the induced adaptation procedure, then the measures obtained from both procedures should cluster on the same underlying factor; if the measures obtained from the two techniques do not assess the same dimension, they should cluster, or load, on different factors. Method Subjects The 18 subjects (4 men, 14 women) were from 15 to 43 years old (median age = 23 years). The subjects’ hearing was tested at 500, 1O00, 2000, and 4000 Hz. Those subjects whose hearing was poorer than 20 dB HTL (American National Standards Institute, 1969) were excluded from the study. All the subjects were allowed to practice the study techniques until they were familiar with them before we began collecting data. All the subjects participated in all three conditions of the study.
Instruments The output of a Bruel and Kjaer Model 1024 sine-random generator was connected to both channels of a Grayson-Stadler 829 dual-channel electronic switch. The output from one channel was connected to a 11I-dB HewlettPackard Model 350-D attenuator, which delivered the signal to the TDH-39 earphone used to provide the stimulus for the adapting ear. The output from the other channel was connected to a Daven 45-dB rotary attenuator, and then to a second 11l-dB Hewlett-Packard attenuator. This stimulus was also presented through a TDH-39 earphone to the comparison ear. All the testing took place in an IAC Model 402A single-wall sound booth. A Bruel and Kjaer precision sound level meter (model 3303) with an octave filter set (model 1613) and an artificial ear with a 6-cc coupler (model 4152) was used to calibrate the 1000-Hz tone for 60 dB SPL. We tested the intensity of the tone for calibration before each subject participated in the experiment.
Procedure Monaural and binaural combinations of 1000 Hz at 60 dB SPL were used for all the testing for the three conditions. The procedure for Condition 1 fol-
-
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lowed the SDLB procedure (Hood, 1950; Weiler et al., 1972; Weiler & Hood, 1977), but in addition to determining adaptation in dB (typical for this procedure), we took MEs of loudness throughout. We followed the three stages of the SDLB procedure: Stage I , the determination of a baseline balance of loudness between simultaneous, intermittent stimulation in two ears; Stage 2, 7 min of constant stimulation of the experimental adapting ear; and Stage 3, a reintroduction of the adjustable, intermittent stimulus in the comparison ear (while constant stimulation was maintained in the adapting ear) to enable the tracking of the dB equivalent of any loudness change in the adapting tone. The uninterrupted ipsilateral stimulation in Stage 2 was presented for 7 min because Weiler et al. (1972) reported that this length of time maximizes SDLB adaptation. Condition 2 was analogous to the SDLB procedure, but we used MEs of loudness and did not adjust the loudness in the comparison ear to equal that in the adapting ear. (Hence there was no dB of adaptation.) Stage 3 of Condition 2 was a replication of the induced adaptation procedure (Botte et al., 1982; Scharf, 1983). Condition 3 consisted of exposing the adapting ear to a continuous tone, and MEs of loudness were taken at the beginning and the end. Botte et al. (1982) and Scharf (1983) reported that this third condition should not produce any adaptation. The experimental conditions are represented in Figure 1.
Results Table 1 contains the values for mean loudness effects. We used Scharf's (1983) adaptation quotient (AQ) to assess the degree of adaptation, or the proportional decline. For Condition 1, the results of the SDLB adaptation (Hood, 1950) indicated a 20.75-dB decline from Stage 1 (baseline) to Stage 3 (final balance). This value is consistent with those that were found in the studies discussed previously. The AQ was 0.345 (Botte et al., 1982; Scharf, 1983). The overall dB adaptation value (which represented a decline of 34.5%) was by far the largest effect (see Table I). In contrast, the ME of adaptation taken during Condition 1 declined proportionally by only 15.4% (AQ = 0.154) from Stage 1 to Stage 3. Condition 2 (no balances), which followed the same form as Condition 1, declined proportionally by 18.9% (AQ = 0.189) from Stage 1 to Stage 3. Thus, the total AQ in Conditions 1 and 2, measured using MEs, was about half the AQ that was found in Condition 1, using the SDLB method. Thus, the SDLB approach yielded much stronger results than the MEs did. The AQ of Condition 3 (the ipsilateral presentation of the Stage 2 adapting tone) was 0.032 (a decline of 3.2%). This value is considerably smaller than the total values for Conditions 1 and 2, but is the same size as the AQ for Stage 2 in Condition 1 and is half the AQ in Stage 2 of Condition 2. Stage 3 reproduced the contralateral induced adaptation procedure of Botte et al.
II
1 Stage3
Condition 3 is equivalent only to Stage 2. Intermittenaesin Stages 1 and 2 are 500 ms on, 500 ms off.
FIGURE 1. Schematic for experimental conditions. Conditions 1 and 2 follow the entire schematic procedure above.
Comparison Ear
Experimental Adapting Ear
Ij
Stage1 1 Stage2
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TABLE 1 Values for Mean Loudness Effects Value
Variable
Initial
Final
Change
AQ
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Condition I
Stage 1 Stage 1 to 2 Stage 2 Stage 2 to 3 Stage 3 Stage 1 to 3 Stage 1 to 3a
60.00 58.00 56.50 54.72 55.05 60.00 60.00
58.00 56.50 54.72 55.05 50.77 50.77 39.25
2.oo 1 .so 1.78 -0.33 4.28 9.23 20.75
.033 .026 .032 - .006 .078 .I54 .345
I .so I .so - 1.22
.025 .026 .078 - .023
4.28 11.33
.080 .189
Condition 2
Stage I Stage I to2 Stage 2 Stage 2 to 3 Stage 3 Stage 1 to 3
60.00 58.50 57.00 52.56 53.78 60.00
Stage 2 equivalent
60.00
58.50 57.00 52.76 53.78 49.50 49.50 Condition 3 58.I I
4.44
1.89
.032
Note. All the data are magnitude estimates (MEs) of loudness. except the data for Stage I to 3'. AQ = adaptation quotient (Scharf, 1983). 'The data for this variable are dB values.
(1982) and Scharf (1983). The AQs for Stage 3 in Conditions 1 and 2 were 0.078 (a 7.8% decline) and 0.080 (an 8.0% decline), respectively-considerably smaller than any of the total AQs. This contradicts the claim of Bone et al. and Scharf that the effects of induced adaptation can replace SDLB effects, even when the fact that Botte et al. and Scharf converted dB values to ME values is taken into account. The primary issue we wanted to address in the factor analysis was whether induced loudness adaptation can adequately account for the major effects that occur with SDLB adaptation. Adaptation is a complex phenomena, whether the SDLB approach, MEs of loudness, or other procedures are used (Weiler, Katbamna, Nileshwar, & Dell'aira 1987, 1988). We used the data from the present study to perform a factor analysis on data that were obtained using the SDLB procedure and MEs of loudness ad-
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aptation. We used 10 of the 14 variables in Table 1. We did not use Stage 1 to 2 and Stage 2 to 3 because they represent simple loss or gain of binaural summation, which is not useful for assessing adaptation effects. (The results of a separate factor analysis, not reported here, confirmed that the Stage 1 to 2 and Stage 2 to 3 changes did not contribute to the final factors.) In addition, the analysis would not tolerate more than 10 variables with the existing sample size. We performed a principle components factor analysis with varimax rotation (SPSS-X,1985). Four factors were found, accounting for 77% of the variance (Factor 1, 32.3%; Factor 2, 18.8%; Factor 3, 15.1%; and Factor 4, 10.7%). The residual variance, caused by unidentifiable factors, was 23%. With this factor analysis, as with any factor analysis, one must remember that the percentage of variance attributed to each factor is subject to statistical variation. interpretation of Factor Loadings
We named the four factors, using the variables that loaded above .80. Three variables loaded at .80 or above for Factor 1 (32%). These variables were the change in ME loudness from Stage 1 to Stage 3, and the changes in ME loudness during monaural Stage 2 and during Stage 3. All these variables involved MEs of loudness that were taken during Condition 1, using the classic SDLB procedure. There were no strong loadings from Condition 2. (Condition 2 was identical to Condition 1, except that the intensity of loudness in the comparison ear was not adjusted to balance the perceived change in loudness during adaptation.) The interaural adjustment effects that occurred during the balancing of perceived loudness may well have been the effect described by Mulligan et al. (1985). Mulligan et al. provided strong evidence that adjustment in one ear can produce (or reveal) loudness changes in the contralateral ear and suggested that this may be related to adaptation effects. Some researchers might argue that because the second variable for Factor 1 (adaptationduring monaural Stage 2) had a high loading, Factor 1 is truly the primary monaural effect of SDLB adaptation. We called Factor 1 Mulligan's Adjustment-Related Loudness Adaptation. Factor 2 accounted for 19% of the overall variance. Only Stage 3 of Condition 2 loaded above .80on this factor. The Stage 3 protocol replicated the induced ME loudness adaptation procedure described by Botte et al. (1982) and Scharf (1983) because there was no balancing or adjustment of the comparison stimulus during Condition 2. The difference in the variables that are important to Factors 1 and 2 makes it clear that the basic measure of induced interaural adaptation is independent of SDLB adaptation, as used in this study. We called Factor 2 Scharf's Interaural Induced Loudness Adaptation.
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Factor 3 accounted for 15% of the total variance and was nearly the same size as Factor 2. Only the dB decline of the SDLB adaptation measured in Condition 1 loaded above .80 on Factor 3. The fact that dB adaptation did not load on Factor 2 was another indication that the induced ME adaptation effect described by Botte et al. (1982) and Scharf (1983) does not replace classical SDLB adaptation. Factor 3 appears to be the essence of what we have called Hood’s Classical dB Adaptation. Factor 4 accounted for 11% of the total variance, leaving 23% of the variance unaccounted for or due to error. Only the overall decline in ME loudness associated with the monaural, steady tone in Condition 3 loaded above .80 on Factor 4. Weiler, Sandman, and Pederson (198 1) argued that a referent stimulus is necessary if adaptation effects are to be fully revealed, but Scharf asserted that the decline in loudness of a steady, monaural tone in the absence of other stimulation should be called simple adaptation. For this reason we called Factor 4 Unreferenced Simple Loudness Adaptation.
Discussion and Conclusions Our purpose in this study was to determine whether the interaural loudness adaptation effect (Botte et al., 1982; Scharf, 1983) could replace the adaptation effect that is associated with Hood’s (1950) classic SDLB procedure. The results of our analysis clearly indicated that the induced adaptation effect was separate (Factor 2) from the primary sources of variance that are associated with SDLB adaptation (Factors I and 3). Factor 4 appeared to be simple, unreferenced ME loudness adaptation, as described by Scharf. We did not consider the differences between referenced and unreferenced monaural adaptation (Weiler et al., 1981) in this study. The SDLB procedure yielded the strongest adaptation effects, perhaps because adaptation is a complex behavior and may be based on several elemental effects. We would need more data to establish a unique multiple regression formula for SDLB adaptation. The results for Factor 1 can be interpreted in more than one way. Factor 1 is associated with the adjustment of the intensity of loudness in the comparison ear so that it equals the level of loudness in the adapting ear. Thus, Factor 1 seems to be the interaural influence that was described by Mulligan et al. (1985). However, the change in ME loudness during the monaural Stage 2, using the SDLB procedure, loaded heavily on Factor 1. This variable is consistent with the original interpretations of SDLB adaptation (Hood, 1950; Small, 1963; Weiler et al., 1972; Weiler & Hood, 1977). Does Factor 1 represent an interaural effect, or does it represent a basic monaural effect revealed by contralateral balancing? The variety of adaptation effects noted in this study and in other studies (Weiler et al., 1987, 1988) caution against a simple decision.
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It has been assumed that adaptation effects represent aspects of hearing that are critical to survival (Hood, 1988, 1990; Weiler et al., 1987, 1988). If this is true, then understanding adaptation effects is an important step toward understanding hearing and human sensation.
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REFERENCES American National Standards Institute. (1969). Specification for audiometers. New York: Author. Bocca, E., & Pestalozza, G.(1959). Auditory adaptation: Theories and facts. Acta Oto-Laryngol,50, 349-353. Botte, M. C., Canevet, G.,& Scharf, B. (1982). Loudness adaptation induced by an intermittent tone. Journal of the Acoustical Society of America, 72, 727-739. Canevet, G., Scharf, B., & Botte, M. C. (1983). Loudness adaptation when induced is real. British Journal of Audiology, 17. 49-57. Davis, J. D., & Weiler, E. M., (1976). Monaural auditory adaptation as measured by simple reaction time. British Journal of Audiology, 10, 102-106. Hood, J. D. (1950). Studies in auditory fatigue and adaptation. Acta Oto-Laryngol. Suppl. 92. Hood, J. D. (1988). Is auditory adaptation different from any other sensory modality? Proceedings of the International Society for Psychophysics (pp. 125-128). Stuling, Scotland. Hood, J. D. (1990). The functional significance of auditory adaptation. British Journal of Audiology, 24, 15 1-1 54. Kachigan, S. D. (1982). Multivariate statistical analysis. New York: Radius Press. Mulligan, B. E., Goodman, L. S., Gleisner, D. P. & Faupel, M. L. (1985). Steps in loudness summation. Journal of the Acoustical Society of America, 77, 11411154.
Scharf, B. (1983). Loudness adaptation. In J. V. Tobias & E. D. Schubert (Eds.), Hearing research and theory: Vol. 2. (pp. 1-56). New Yo&: Academic Press. Small, A. M. (1963). Auditory adaptation. In J. Jerger (Ed.), Modem developments in audiology (pp. 287-336). New York: Academic Press. SPSS-X (Statistical package for the social sciences). (1985). (3rd ed.). Chicago, IL: McGraw-Hill. Stokinger. T. E., & Studebaker, G. A. (1968). Measurement of perstimulatory loudness adaptation. Journal of the Acoustical Society of America, 44, 250-256. von Bekesy, G. (1958). Funneling in the nervous system. Journal of the Acoustical Society of America, 30, 399-4 12. Weiler, E. M., Loeb, M., & Alluisi, E. A. (1972). Auditory adaptation and its relationship to a model for loudness. Journal of the Acoustical Society of America, 51,638-643.
Weiler, E. M., & Friedman, L. (1973). Monaural heterophonic auditory adaptation. 87th Meeting of the Acoustical Society of America, Los Angeles (Suppl. 1). Journal of the Acoustical Society of America, 55. Weiler, E. M., & Gross,L. F. (1976). A positive measure of monaural heterophonic auditory adaptation. Journal of Auditory Research, 16, 20-23. Weiler, E. M., & Hood, J. D. (1977). An improved model for loudness coding during auditory adaptation. Audiology, 16. 499-506. Weiler, E. M., Sandman, D. E., & Pederson. L. M. (1981). Magnitude estimates of loudness adaptation at 60 dB SPL. British Journal of Audiology. 15, 201-204.
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Weiler, E. M . , Katbarnna, B . , Nileshwar, N . , & Dell'aira. A. (1987). Redundancy: A similar principle in independent adaptation techniques. Journal of General Psychology, 114. 41 1-421. Weiler, E. M . , Katbarnna, B . , Nileshwar, N . , & Dell'aira, A. (1988). Redundancy: A similar principle in independent adaptation techniques. [Errata]. Journal ofGenera1 Psychology, 115. 33 1.
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Received June 22, 1992
The Journal of General Psychology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/vgen20
Four Triggering Factors in Loudness Adaptation a
a
Ernest M. Weiler , Laurie Smith Gold , David E. a
Sandman & Joel S. Warm
b
a
Department of Communication Science & Disorders , University of Cincinnati , USA b
Department of Psychology , University of Cincinnati , USA Published online: 06 Jul 2010.
To cite this article: Ernest M. Weiler , Laurie Smith Gold , David E. Sandman & Joel S. Warm (1992) Four Triggering Factors in Loudness Adaptation, The Journal of General Psychology, 119:4, 325-334, DOI: 10.1080/00221309.1992.9921175 To link to this article: http://dx.doi.org/10.1080/00221309.1992.9921175
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content.
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The Journol of General Psychology, 119(4). 325-334
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Four Triggering Factors in Loudness Adaptation ERNEST M. WEILER LAURIE SMITH GOLD DAVID E. SANDMAN Department of Communication Science & Disorders University of Cincinnati
JOEL S. WARM
Department of Psychology University of Cincinnati
ABSTRACT. A factor analysis was used to determine whether induced loudness adaptation (Botte, Canevet, & Scharf, 1982; Scharf, 1983) and adaptation measured by Hood’s ( 1950) classic Simultaneous Dichotic Loudness Balance technique (SDLB) would cluster on the same factors. The two phenomena did not cluster on the same factors; thus, induced adaptation cannot replace SDLB adaptation. Four independent factors that trigger auditory adaptation were identified in the factor analysis.
HOOD’S MONUMENTAL STUDY (1950) has stimulated much research in the area of auditory adaptation. However, subsequent studies using a variety of techniques have resulted in conflicting conclusions. In Hood’s classic (1950) Simultaneous Dichotic Loudness Balance (SDLB) technique, one ear received a continuous, adapting tone of constant intensity while the other ear received an intermittent, adjustable comparison This article evolvedfrom a project conceived by Ernest M . Weiler and Laurie Smith Gold as part of Ms. Gold’s MA requirements; her laboratory skills were essential to the research. We wish to acknowledge the help of h u r a Kretschmer, Angel Dell‘aira, Kenneth Donnelly, Satish Venkatesan. Yea Wen Shiau. Bertram Scharf. and J. Derek Hood. Address correspondence to Ernest M . Weiler. Psychoacoustics Lahoratoy M.L. #379, Department of CommunicationScience & Disorders, University of Cincinnati, Cincinnati, OH 45221. 325
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tone. After several minutes of stimulation, the listener was to set the adjustable tone so that it would be as loud as he or she thought the adapting tone was. The listener set the adjustable tone so that it was much less intense than the adapting tone. The value of the dB decline in the comparison ear was considered to be the measure of monaural adaptation to the continuous tone. Bocca and Pestalozza ( I 959) and Stokinger and Studebaker ( 1968), among others, have challenged the validity of the SDLB procedure, suggesting that the time-based changes that occur with the use of the SDLB technique are due to interaural artifacts rather than the adaptation of the continuously stimulated ear. A number of researchers who used monaural techniques have answered this challenge by demonstrating adaptation effects that were comparable in magnitude to those found with the binaural SDLB procedure. For example, Weiler and Friedman (1973) and Weiler and (Friedman) Gross (1976) used a monaural heterophonic balance procedure that resulted in 22 dB of adaptation, the same amount Weiler, Loeb, and Alluisi (1972) found, using the SDLB. Davis and Weiler (1976) used a monaural reaction time technique and found that response slowed significantly, as would be expected with a decline in loudness. Moreover, Weiler, Sandman, and Pederson (1981) devised a monaural loudness-estimation technique with an ipsilateral loudness referent that demonstrated substantial loudness adaptation, as measured by magnitude estimates (MEs). These results were replicated by Canevet, Scharf, and Botte (1983). Botte, Canevet, and Scharf ( 1982) and Scharf (1983) tested the validity of the SDLB in still another way, using a procedure in which MEs, instead of the contralateral intermittent tone, were used to indicate the loudness of the continuous, adapting tone. Adaptation effectsoccurred when the functionally neutral intermittent tone was present, but not when it was absent. Botte et al. and Scharf attributed these adaptation effects, which they labeled induced adaptation, to an artifact of psychophysical contrast based on funneling (von Bekesy, 1958). Botte et al. and Scharf would have us believe that their results duplicate most or all of the effects that occur with the SDLB procedure, but the induced adaptation technique differs from the SDLB approach in two important ways: 1. Given the imprecision that exists when MEs of loudness are con-
verted to dB changes, the magnitude of the induced adaptation effects is considerably smaller than that of the adaptation effects obtained with the SDLB technique. 2. Using the induced adaptation technique eliminates adjustment in the comparison ear, and Mulligan, Goodman, Gleisner, and Faupel (1985) have demonstrated that adjusting the intensity of sound in one ear actively affects loudness in the other.
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In the present study, we used factor analysis to determine whether the results of the induced adaptation procedure explain those that are obtained with the SDLB technique. In factor analysis, correlations between measurements are used to group similar variables (Kachigan, 1982) that define the underlying dimensions, or factors, of behavior. If the adaptation measured by the SDLB technique is subsumed by that in the induced adaptation procedure, then the measures obtained from both procedures should cluster on the same underlying factor; if the measures obtained from the two techniques do not assess the same dimension, they should cluster, or load, on different factors. Method Subjects The 18 subjects (4 men, 14 women) were from 15 to 43 years old (median age = 23 years). The subjects’ hearing was tested at 500, 1O00, 2000, and 4000 Hz. Those subjects whose hearing was poorer than 20 dB HTL (American National Standards Institute, 1969) were excluded from the study. All the subjects were allowed to practice the study techniques until they were familiar with them before we began collecting data. All the subjects participated in all three conditions of the study.
Instruments The output of a Bruel and Kjaer Model 1024 sine-random generator was connected to both channels of a Grayson-Stadler 829 dual-channel electronic switch. The output from one channel was connected to a 11I-dB HewlettPackard Model 350-D attenuator, which delivered the signal to the TDH-39 earphone used to provide the stimulus for the adapting ear. The output from the other channel was connected to a Daven 45-dB rotary attenuator, and then to a second 11l-dB Hewlett-Packard attenuator. This stimulus was also presented through a TDH-39 earphone to the comparison ear. All the testing took place in an IAC Model 402A single-wall sound booth. A Bruel and Kjaer precision sound level meter (model 3303) with an octave filter set (model 1613) and an artificial ear with a 6-cc coupler (model 4152) was used to calibrate the 1000-Hz tone for 60 dB SPL. We tested the intensity of the tone for calibration before each subject participated in the experiment.
Procedure Monaural and binaural combinations of 1000 Hz at 60 dB SPL were used for all the testing for the three conditions. The procedure for Condition 1 fol-
-
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lowed the SDLB procedure (Hood, 1950; Weiler et al., 1972; Weiler & Hood, 1977), but in addition to determining adaptation in dB (typical for this procedure), we took MEs of loudness throughout. We followed the three stages of the SDLB procedure: Stage I , the determination of a baseline balance of loudness between simultaneous, intermittent stimulation in two ears; Stage 2, 7 min of constant stimulation of the experimental adapting ear; and Stage 3, a reintroduction of the adjustable, intermittent stimulus in the comparison ear (while constant stimulation was maintained in the adapting ear) to enable the tracking of the dB equivalent of any loudness change in the adapting tone. The uninterrupted ipsilateral stimulation in Stage 2 was presented for 7 min because Weiler et al. (1972) reported that this length of time maximizes SDLB adaptation. Condition 2 was analogous to the SDLB procedure, but we used MEs of loudness and did not adjust the loudness in the comparison ear to equal that in the adapting ear. (Hence there was no dB of adaptation.) Stage 3 of Condition 2 was a replication of the induced adaptation procedure (Botte et al., 1982; Scharf, 1983). Condition 3 consisted of exposing the adapting ear to a continuous tone, and MEs of loudness were taken at the beginning and the end. Botte et al. (1982) and Scharf (1983) reported that this third condition should not produce any adaptation. The experimental conditions are represented in Figure 1.
Results Table 1 contains the values for mean loudness effects. We used Scharf's (1983) adaptation quotient (AQ) to assess the degree of adaptation, or the proportional decline. For Condition 1, the results of the SDLB adaptation (Hood, 1950) indicated a 20.75-dB decline from Stage 1 (baseline) to Stage 3 (final balance). This value is consistent with those that were found in the studies discussed previously. The AQ was 0.345 (Botte et al., 1982; Scharf, 1983). The overall dB adaptation value (which represented a decline of 34.5%) was by far the largest effect (see Table I). In contrast, the ME of adaptation taken during Condition 1 declined proportionally by only 15.4% (AQ = 0.154) from Stage 1 to Stage 3. Condition 2 (no balances), which followed the same form as Condition 1, declined proportionally by 18.9% (AQ = 0.189) from Stage 1 to Stage 3. Thus, the total AQ in Conditions 1 and 2, measured using MEs, was about half the AQ that was found in Condition 1, using the SDLB method. Thus, the SDLB approach yielded much stronger results than the MEs did. The AQ of Condition 3 (the ipsilateral presentation of the Stage 2 adapting tone) was 0.032 (a decline of 3.2%). This value is considerably smaller than the total values for Conditions 1 and 2, but is the same size as the AQ for Stage 2 in Condition 1 and is half the AQ in Stage 2 of Condition 2. Stage 3 reproduced the contralateral induced adaptation procedure of Botte et al.
II
1 Stage3
Condition 3 is equivalent only to Stage 2. Intermittenaesin Stages 1 and 2 are 500 ms on, 500 ms off.
FIGURE 1. Schematic for experimental conditions. Conditions 1 and 2 follow the entire schematic procedure above.
Comparison Ear
Experimental Adapting Ear
Ij
Stage1 1 Stage2
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TABLE 1 Values for Mean Loudness Effects Value
Variable
Initial
Final
Change
AQ
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Condition I
Stage 1 Stage 1 to 2 Stage 2 Stage 2 to 3 Stage 3 Stage 1 to 3 Stage 1 to 3a
60.00 58.00 56.50 54.72 55.05 60.00 60.00
58.00 56.50 54.72 55.05 50.77 50.77 39.25
2.oo 1 .so 1.78 -0.33 4.28 9.23 20.75
.033 .026 .032 - .006 .078 .I54 .345
I .so I .so - 1.22
.025 .026 .078 - .023
4.28 11.33
.080 .189
Condition 2
Stage I Stage I to2 Stage 2 Stage 2 to 3 Stage 3 Stage 1 to 3
60.00 58.50 57.00 52.56 53.78 60.00
Stage 2 equivalent
60.00
58.50 57.00 52.76 53.78 49.50 49.50 Condition 3 58.I I
4.44
1.89
.032
Note. All the data are magnitude estimates (MEs) of loudness. except the data for Stage I to 3'. AQ = adaptation quotient (Scharf, 1983). 'The data for this variable are dB values.
(1982) and Scharf (1983). The AQs for Stage 3 in Conditions 1 and 2 were 0.078 (a 7.8% decline) and 0.080 (an 8.0% decline), respectively-considerably smaller than any of the total AQs. This contradicts the claim of Bone et al. and Scharf that the effects of induced adaptation can replace SDLB effects, even when the fact that Botte et al. and Scharf converted dB values to ME values is taken into account. The primary issue we wanted to address in the factor analysis was whether induced loudness adaptation can adequately account for the major effects that occur with SDLB adaptation. Adaptation is a complex phenomena, whether the SDLB approach, MEs of loudness, or other procedures are used (Weiler, Katbamna, Nileshwar, & Dell'aira 1987, 1988). We used the data from the present study to perform a factor analysis on data that were obtained using the SDLB procedure and MEs of loudness ad-
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aptation. We used 10 of the 14 variables in Table 1. We did not use Stage 1 to 2 and Stage 2 to 3 because they represent simple loss or gain of binaural summation, which is not useful for assessing adaptation effects. (The results of a separate factor analysis, not reported here, confirmed that the Stage 1 to 2 and Stage 2 to 3 changes did not contribute to the final factors.) In addition, the analysis would not tolerate more than 10 variables with the existing sample size. We performed a principle components factor analysis with varimax rotation (SPSS-X,1985). Four factors were found, accounting for 77% of the variance (Factor 1, 32.3%; Factor 2, 18.8%; Factor 3, 15.1%; and Factor 4, 10.7%). The residual variance, caused by unidentifiable factors, was 23%. With this factor analysis, as with any factor analysis, one must remember that the percentage of variance attributed to each factor is subject to statistical variation. interpretation of Factor Loadings
We named the four factors, using the variables that loaded above .80. Three variables loaded at .80 or above for Factor 1 (32%). These variables were the change in ME loudness from Stage 1 to Stage 3, and the changes in ME loudness during monaural Stage 2 and during Stage 3. All these variables involved MEs of loudness that were taken during Condition 1, using the classic SDLB procedure. There were no strong loadings from Condition 2. (Condition 2 was identical to Condition 1, except that the intensity of loudness in the comparison ear was not adjusted to balance the perceived change in loudness during adaptation.) The interaural adjustment effects that occurred during the balancing of perceived loudness may well have been the effect described by Mulligan et al. (1985). Mulligan et al. provided strong evidence that adjustment in one ear can produce (or reveal) loudness changes in the contralateral ear and suggested that this may be related to adaptation effects. Some researchers might argue that because the second variable for Factor 1 (adaptationduring monaural Stage 2) had a high loading, Factor 1 is truly the primary monaural effect of SDLB adaptation. We called Factor 1 Mulligan's Adjustment-Related Loudness Adaptation. Factor 2 accounted for 19% of the overall variance. Only Stage 3 of Condition 2 loaded above .80on this factor. The Stage 3 protocol replicated the induced ME loudness adaptation procedure described by Botte et al. (1982) and Scharf (1983) because there was no balancing or adjustment of the comparison stimulus during Condition 2. The difference in the variables that are important to Factors 1 and 2 makes it clear that the basic measure of induced interaural adaptation is independent of SDLB adaptation, as used in this study. We called Factor 2 Scharf's Interaural Induced Loudness Adaptation.
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Factor 3 accounted for 15% of the total variance and was nearly the same size as Factor 2. Only the dB decline of the SDLB adaptation measured in Condition 1 loaded above .80 on Factor 3. The fact that dB adaptation did not load on Factor 2 was another indication that the induced ME adaptation effect described by Botte et al. (1982) and Scharf (1983) does not replace classical SDLB adaptation. Factor 3 appears to be the essence of what we have called Hood’s Classical dB Adaptation. Factor 4 accounted for 11% of the total variance, leaving 23% of the variance unaccounted for or due to error. Only the overall decline in ME loudness associated with the monaural, steady tone in Condition 3 loaded above .80 on Factor 4. Weiler, Sandman, and Pederson (198 1) argued that a referent stimulus is necessary if adaptation effects are to be fully revealed, but Scharf asserted that the decline in loudness of a steady, monaural tone in the absence of other stimulation should be called simple adaptation. For this reason we called Factor 4 Unreferenced Simple Loudness Adaptation.
Discussion and Conclusions Our purpose in this study was to determine whether the interaural loudness adaptation effect (Botte et al., 1982; Scharf, 1983) could replace the adaptation effect that is associated with Hood’s (1950) classic SDLB procedure. The results of our analysis clearly indicated that the induced adaptation effect was separate (Factor 2) from the primary sources of variance that are associated with SDLB adaptation (Factors I and 3). Factor 4 appeared to be simple, unreferenced ME loudness adaptation, as described by Scharf. We did not consider the differences between referenced and unreferenced monaural adaptation (Weiler et al., 1981) in this study. The SDLB procedure yielded the strongest adaptation effects, perhaps because adaptation is a complex behavior and may be based on several elemental effects. We would need more data to establish a unique multiple regression formula for SDLB adaptation. The results for Factor 1 can be interpreted in more than one way. Factor 1 is associated with the adjustment of the intensity of loudness in the comparison ear so that it equals the level of loudness in the adapting ear. Thus, Factor 1 seems to be the interaural influence that was described by Mulligan et al. (1985). However, the change in ME loudness during the monaural Stage 2, using the SDLB procedure, loaded heavily on Factor 1. This variable is consistent with the original interpretations of SDLB adaptation (Hood, 1950; Small, 1963; Weiler et al., 1972; Weiler & Hood, 1977). Does Factor 1 represent an interaural effect, or does it represent a basic monaural effect revealed by contralateral balancing? The variety of adaptation effects noted in this study and in other studies (Weiler et al., 1987, 1988) caution against a simple decision.
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It has been assumed that adaptation effects represent aspects of hearing that are critical to survival (Hood, 1988, 1990; Weiler et al., 1987, 1988). If this is true, then understanding adaptation effects is an important step toward understanding hearing and human sensation.
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REFERENCES American National Standards Institute. (1969). Specification for audiometers. New York: Author. Bocca, E., & Pestalozza, G.(1959). Auditory adaptation: Theories and facts. Acta Oto-Laryngol,50, 349-353. Botte, M. C., Canevet, G.,& Scharf, B. (1982). Loudness adaptation induced by an intermittent tone. Journal of the Acoustical Society of America, 72, 727-739. Canevet, G., Scharf, B., & Botte, M. C. (1983). Loudness adaptation when induced is real. British Journal of Audiology, 17. 49-57. Davis, J. D., & Weiler, E. M., (1976). Monaural auditory adaptation as measured by simple reaction time. British Journal of Audiology, 10, 102-106. Hood, J. D. (1950). Studies in auditory fatigue and adaptation. Acta Oto-Laryngol. Suppl. 92. Hood, J. D. (1988). Is auditory adaptation different from any other sensory modality? Proceedings of the International Society for Psychophysics (pp. 125-128). Stuling, Scotland. Hood, J. D. (1990). The functional significance of auditory adaptation. British Journal of Audiology, 24, 15 1-1 54. Kachigan, S. D. (1982). Multivariate statistical analysis. New York: Radius Press. Mulligan, B. E., Goodman, L. S., Gleisner, D. P. & Faupel, M. L. (1985). Steps in loudness summation. Journal of the Acoustical Society of America, 77, 11411154.
Scharf, B. (1983). Loudness adaptation. In J. V. Tobias & E. D. Schubert (Eds.), Hearing research and theory: Vol. 2. (pp. 1-56). New Yo&: Academic Press. Small, A. M. (1963). Auditory adaptation. In J. Jerger (Ed.), Modem developments in audiology (pp. 287-336). New York: Academic Press. SPSS-X (Statistical package for the social sciences). (1985). (3rd ed.). Chicago, IL: McGraw-Hill. Stokinger. T. E., & Studebaker, G. A. (1968). Measurement of perstimulatory loudness adaptation. Journal of the Acoustical Society of America, 44, 250-256. von Bekesy, G. (1958). Funneling in the nervous system. Journal of the Acoustical Society of America, 30, 399-4 12. Weiler, E. M., Loeb, M., & Alluisi, E. A. (1972). Auditory adaptation and its relationship to a model for loudness. Journal of the Acoustical Society of America, 51,638-643.
Weiler, E. M., & Friedman, L. (1973). Monaural heterophonic auditory adaptation. 87th Meeting of the Acoustical Society of America, Los Angeles (Suppl. 1). Journal of the Acoustical Society of America, 55. Weiler, E. M., & Gross,L. F. (1976). A positive measure of monaural heterophonic auditory adaptation. Journal of Auditory Research, 16, 20-23. Weiler, E. M., & Hood, J. D. (1977). An improved model for loudness coding during auditory adaptation. Audiology, 16. 499-506. Weiler, E. M., Sandman, D. E., & Pederson. L. M. (1981). Magnitude estimates of loudness adaptation at 60 dB SPL. British Journal of Audiology. 15, 201-204.
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Weiler, E. M . , Katbarnna, B . , Nileshwar, N . , & Dell'aira. A. (1987). Redundancy: A similar principle in independent adaptation techniques. Journal of General Psychology, 114. 41 1-421. Weiler, E. M . , Katbarnna, B . , Nileshwar, N . , & Dell'aira, A. (1988). Redundancy: A similar principle in independent adaptation techniques. [Errata]. Journal ofGenera1 Psychology, 115. 33 1.
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Received June 22, 1992
