Repeated Measurement of Absolute and Relative Judgments of Loudness: Clinical Relevance for Prescriptive Fitting of Aided Target Gains for soft, Comfortable, and Loud, But Ok Sound Levels

Abstract

This study was undertaken with the purpose of streamlining clinical measures of loudness growth to facilitate and enhance prescriptive fitting of nonlinear hearing aids. Repeated measures of loudness at 500 and 3,000 Hz were obtained bilaterally at monthly intervals over a 6-month period from three groups of young adult listeners. All volunteers had normal audiometric hearing sensitivity and middle ear function, and all denied problems related to sound tolerance. Group 1 performed judgments of and for presentation of ascending sound levels. We defined these judgments operationally as absolute judgments of loudness. Group 2 initially performed loudness judgments across a continuum of seven loudness categories ranging from judgments of to for presentation of ascending sound levels per the Contour Test of Loudness; we defined these judgments as relative judgments of loudness. In the same session, they then performed the absolute judgments for and sound levels. Group 3 performed the same set of loudness judgments as did group 2, but the task order was reversed such that they performed the absolute judgments initially within each test session followed by the relative judgments. The key findings from this study were as follows: (1) Within group, the absolute and relative tasks yielded clinically similar judgments for and for sound levels. These judgments were largely independent of task order, ear, frequency, or trial order within a given session. (2) Loudness judgments increased, on average, by ∼3 dB between the first and last test session, which is consistent with the commonly reported acclimatization effect reported for incremental changes in loudness discomfort levels as a consequence of chronic bilateral hearing aid use. (3) Measured and predicted comfortable judgments of loudness were in good agreement for the individual listener and for groups of listeners. These comfortable judgments bisect the measured levels judged for and for sounds. (4) Loudness judgments within the same loudness category varied across listeners within group by as much as 50 to 60 dB. Such large variation in judgments of loudness is problematic, especially because hearing-impaired listeners are known to exhibit similarly large ranges of intersubject response variation and, yet, poplar prescriptive fitting strategies continue to use average rather than individual loudness data to fit nonlinear hearing aids. The primary conclusions drawn from these findings are that reliable absolute judgments of and are clinically practical and economical to measure and, from these judgments, good estimates of comfortable loudness can also be predicted for individuals or for groups of listeners. Such loudness data, as measured as described in this report, offer promise for streamlining and enhancing prescriptive fitting of nonlinear hearing aids to target gain settings for (audible),, and (tolerable) sound inputs for the individual listener.

Potential Consequences of Spectral and Binaural Loudness Summation for Bilateral Hearing Aid Fitting

“…Figure 9 ), taking the effect of compression into account still leaves output level differences in individual binaural loudness summation between 14 and 29 dB. These values are in accordance with the large interindividual differences in LDLs found by Formby et al. (2017) for monaural warble tones.…”

“…Loudness complaints remain a major reason for revisiting the hearing aid dispenser (Jenstad, Van Tasell, & Ewert, 2003), and aversiveness of loud sounds is one of the main reasons to be dissatisfied with a hearing aid fitting (Hickson, Clutterbuck, & Khan, 2010). Discomfort of loud sound and its importance for hearing aid fitting have been extensively investigated (e.g., Formby, Payne, Yang, Wu, & Parton, 2017;Hawley, Sherlock, & Formby, 2017;Mueller & Bentler, 2005). The relationship between measured loudness discomfort levels and ratings for satisfaction, however, is weak (Zaugg, Thielman, Griest, & Henry, 2016), and the loudness judgments within the same loudness category varied across listeners within a group by as much as 50 to 60 dB (Formby et al, 2017).…”

Uni- and bilateral spectral loudness summation and binaural loudness summation with loudness matching and categorical loudness scaling

“…And this range increased further for loudness levels above 35 CU. This is in agreement with the findings from Formby et al (2017) who found loudness judgments within the same loudness category to vary across listeners by as much as 50-60 dB. Van Beurden et al (2018) found comparable ranges between lowest and highest levels judged to have equal loudness for international female noise and uniformly exciting noise of 17 Bark Bandwidth, presented unilaterally and bilaterally after narrowband loudness compensation.…”

“…In studies on the benefit of hearing aids aversiveness of loud sounds remains an important reason for dissatisfaction with hearing aids (Kochkin 2000;Jenstad, Van Tasell, and Ewert 2003;Boymans et al 2008;Hickson, Clutterbuck, and Khan 2010;Franks and Beckmann 1985;EuroTrak Germany 2018). However, in most clinical settings individual frequency-specific loudness discomfort levels (LDLs) are not routinely measured (Mueller 2003), as loudness measurements are deemed time-consuming and tedious for patients to perform (Formby et al 2017). In many hearing aid fittings, only hearing thresholds are included and the uncomfortable loudness level is estimated, for instance NAL-NL1 and NAL-NL2 do not allow to enter patient-specific LDLs (Keidser et al 2011).…”

“…Kamm, Dirks, andMickey 1978, Formby et al 2017) LDLs were found to vary considerably for subjects with different hearing losses but were also found to vary significantly for subjects with the same degree of hearing loss. Formby et al (2017) reported loudness judgments within the same loudness category to vary across a group of 30 normal-hearing listeners by as much as 50 to 60 dB. Nelson et al (2018) allowed a group of mild to moderate hearing-impaired listeners to self-adjust hearing aid gain for speech understanding in a variety of quiet and noisy listening conditions.…”