Loudness Judgments Research Articles

Perceived auditory dynamic range is enhanced with wrist-based tactile stimulation.

Tactile stimulation has been shown to increase auditory loudness judgments in listeners. This bias could be utilized to enhance perception for people with deficiencies in auditory intensity perception, such as cochlear implant users. However, several aspects of this enhancement remain uncertain. For instance, does the tactile stimulation need to be applied to the hand or body, or can it be applied to the wrist? Furthermore, can the tactile stimulation both amplify and attenuate the perceived auditory loudness? To address these questions, two loudness-matching experiments were conducted. Participants matched a comparison auditory stimulus with an auditory reference, either with or without spectro-temporally identical tactile stimulation. In the first experiment, fixed-level tactile stimulation was administered to the wrist during the comparison stimulus to assess whether perceived auditory loudness increased. The second experiment replicated the same conditions but introduced tactile stimulation to both the reference and comparison, aiming to investigate the potential decrease in perceived auditory loudness when the two tactile accompaniments were incongruent between the reference and comparison. The results provide evidence supporting the existence of the tactile loudness bias in each experiment and are a step towards wrist-based haptic devices that modulate the auditory dynamic range for a user.

Results of a 6-Month Field Trial of a Transitional Intervention for Debilitating Hyperacusis.

We present results from a 6-month field trial of a transitional intervention for debilitating primary hyperacusis, including a combination of structured counseling; promotion of safe, comfortable, and healthy sound exposure; and therapeutic broadband sound from sound generators. This intervention is designed to overcome barriers to successful delivery of therapeutic sound as a tool to downregulate neural hyperactivity in the central auditory pathways (i.e., the maladaptive mechanism believed to account for primary hyperacusis) and, together with the counseling, reduce the associated negative emotional and physiological reactions to debilitating hyperacusis. Twelve adults with normal or near-normal audiometric thresholds, complaints consistent with their pretreatment loudness discomfort levels ≤ 75 dB HL at multiple frequencies, and hearing questionnaire scores ≥ 24 completed the sound therapy-based intervention. The low-level broadband therapeutic sound was delivered by ear-level devices fitted bilaterally with either occluding earpieces and output-limiting loudness suppression (LS; to limit exposure to offensive sound levels) or open domes to maximize comfort and exposure to sound therapy. Thresholds for LS (primary outcome) were incrementally adjusted across six monthly visits based on treatment-driven change in loudness judgments for running speech in sound field. Secondary outcomes included categorical loudness judgments, speech understanding, and questionnaires to assess the hyperacusis problem, quality of life, and depression. An exit survey assessed satisfaction with and benefit from the intervention and the counseling, therapeutic sound, and LS components. The mean change in LS (34.8 dB) was highly significant (effect size = 2.045). Eleven of 12 participants achieved ≥ 16-dB change in LS, consistent with highly significant change in sound-based questionnaire scores. Exit surveys indicated satisfaction with and benefit from the intervention. The transitional intervention was successful in improving the hyperacusis conditions of 11 of 12 study participants while reducing their sound avoidance behaviors and reliance on sound protection.

Relationships between loudness and preference judgments for fan sounds as a function of the reference sound pressure level

In a prior study, the level of fan test sounds was adjusted in a listening test using an adaptive procedure, until they became equally loud or equally preferred as a reference sound at a fixed level. Depending on the test sound, level reductions of up to 15 dB compared to the 60 dB(A) reference level were necessary to reach equal loudness or preference compared to the reference sound. It turned out that the preference-equivalent levels were highly correlated with the loudness-equivalent levels, indicating that the preference decision and the loudness judgment were closely related to each other. In a follow-up study, the measurements were extended towards a higher reference level of 75 dB(A) and a lower reference level of 45 dB(A). The preference-equivalent levels obtained at 75 dB(A) were again closely related to the loudness-equivalent levels. For the lower reference level of 45 dB(A), the preference-equivalent levels deviate from the loudness-equivalent levels by 3.5 dB on average and also the inter-individual variability increased. This result suggests an increasing effect of additional fan-noise characteristics to play a role for the preference decisions on top of the perceived loudness especially at low absolute sound pressure levels.

Influence of Color on Loudness Perception of Household Appliances: Case of a Coffee Maker

Previous studies have investigated the effect of color on the assessment of loudness in various cases, such as cars, trains, and concert halls. This study sets out to explore the influence of color on the loudness perception of household appliances, in particular in the case of coffee makers. To this end, images of a coffee maker colored in black, red, dark green, light blue, light green, and white were displayed to participants during a magnitude estimation task. In a repeated measures design, the sound of a coffee maker was used synchronously as a stimulus presented in different sound levels (74, 78, 82, and 86 dB LAeq). The sample of participants was selected to be gender balanced and unfamiliar with similar experiments. Statistical analysis suggested that the color of the visual stimulus had no influence on loudness judgments. However, a gender-based statistically significant influence regarding the color of the coffee maker on loudness evaluation was found for females. An interpretation of the results is attempted in the discussion. The results of this study suggest that since there is the possibility of gender differences in the assessment of loudness for household appliances, special care should be taken in similar studies to account for these effects. Finally, these gender differences could possibly be utilized for product sound design and product marketing where the appropriate use of color has been found to be effective.

Relationship of noise history to perceived loudness and physiological arousal from noise

Chronic exposure to noise is a well-documented health hazard (Suter, 1991). In this study, we investigated whether an individuals’ self-reported noise history (exposure, sensitivity, and annoyance) correlated with noise-elicited physiologic arousal. We measured pupil dilation responses and loudness judgments to varying types of noise and related those to self-identified noise history. We hypothesized that increased history of exposure or annoyance would be correlated with perceived loudness and arousal from noise. Five colors (spectra) of noise were generated with the same sound pressure levels within the band 1000–4000 Hz but with different slopes of spectral energy below and above the band. Changes in participant pupil dilation responses elicited by each noise type were used as an assessment of physiological stress response to noise stimuli. Participants also adjusted the loudness of two randomized noise spectra until they were determined to be of equal loudness. Preliminary data suggest that the perception of loudness and levels of arousal differed depending on the color spectrum of noise. Relationships between the loudness judgments, self-reported noise history, and observed physiologic data will be further discussed. Results have implications for understanding the behavioral and physiological effects of chronic exposure to noise. [Robert Young, NIDCD R01DC017114 (Winn).]

Temporal loudness weights: Primacy effects, loudness dominance and their interaction.

Loudness judgments of sounds varying in level across time show a non-uniform temporal weighting, with increased weights assigned to the beginning of the sound (primacy effect). In addition, higher weights are observed for temporal components that are higher in level than the remaining components (loudness dominance). In three experiments, sounds consisting of 100- or 475-ms Gaussian wideband noise segments with random level variations were presented and either none, the first, or a central temporal segment was amplified or attenuated. In Experiment 1, the sounds consisted of four 100-ms segments that were separated by 500-ms gaps. Previous experiments did not show a primacy effect in such a condition. In Experiment 2, four- or ten-100-ms-segment sounds without gaps between the segments were presented to examine the interaction between the primacy effect and level dominance. As expected, for the sounds with segments separated by gaps, no primacy effect was observed, but weights on amplified segments were increased and weights on attenuated segments were decreased. For the sounds with contiguous segments, a primacy effect as well as effects of relative level (similar to those in Experiment 1) were found. For attenuation, the data indicated no substantial interaction between the primacy effect and loudness dominance, whereas for amplification an interaction was present. In Experiment 3, sounds consisting of either four contiguous 100-ms or 475-ms segments, or four 100-ms segments separated by 500-ms gaps were presented. Effects of relative level were more pronounced for the contiguous sounds. Across all three experiments, the effects of relative level were more pronounced for attenuation. In addition, the effects of relative level showed a dependence on the position of the change in level, with opposite direction for attenuation compared to amplification. Some of the results are in accordance with explanations based on masking effects on auditory intensity resolution.

Manual Gestures Modulate Early Neural Responses in Loudness Perception.

How different sensory modalities interact to shape perception is a fundamental question in cognitive neuroscience. Previous studies in audiovisual interaction have focused on abstract levels such as categorical representation (e.g., McGurk effect). It is unclear whether the cross-modal modulation can extend to low-level perceptual attributes. This study used motional manual gestures to test whether and how the loudness perception can be modulated by visual-motion information. Specifically, we implemented a novel paradigm in which participants compared the loudness of two consecutive sounds whose intensity changes around the just noticeable difference (JND), with manual gestures concurrently presented with the second sound. In two behavioral experiments and two EEG experiments, we investigated our hypothesis that the visual-motor information in gestures would modulate loudness perception. Behavioral results showed that the gestural information biased the judgment of loudness. More importantly, the EEG results demonstrated that early auditory responses around 100 ms after sound onset (N100) were modulated by the gestures. These consistent results in four behavioral and EEG experiments suggest that visual-motor processing can integrate with auditory processing at an early perceptual stage to shape the perception of a low-level perceptual attribute such as loudness, at least under challenging listening conditions.

Toward an Individual Binaural Loudness Model for Hearing Aid Fitting and Development.

The individual loudness perception of a patient plays an important role in hearing aid satisfaction and use in daily life. Hearing aid fitting and development might benefit from individualized loudness models (ILMs), enabling better adaptation of the processing to individual needs. The central question is whether additional parameters are required for ILMs beyond non-linear cochlear gain loss and linear attenuation common to existing loudness models for the hearing impaired (HI). Here, loudness perception in eight normal hearing (NH) and eight HI listeners was measured in conditions ranging from monaural narrowband to binaural broadband, to systematically assess spectral and binaural loudness summation and their interdependence. A binaural summation stage was devised with empirical monaural loudness judgments serving as input. While NH showed binaural inhibition in line with the literature, binaural summation and its inter-subject variability were increased in HI, indicating the necessity for individualized binaural summation. Toward ILMs, a recent monaural loudness model was extended with the suggested binaural stage, and the number and type of additional parameters required to describe and to predict individual loudness were assessed. In addition to one parameter for the individual amount of binaural summation, a bandwidth-dependent monaural parameter was required to successfully account for individual spectral summation.

Audio-Visual Interactions and the Influence of Colour on Noise Annoyance Evaluations

This study aims to examine the influence of colour exposure on noise annoyance. Previous studies in the literature have focused mostly on the effects of colour exposure on loudness judgements; however, due to the cognitive nature of multisensory perception, the influence of colour on noise annoyance also needs to be investigated. Our experiments were designed to administer non-information-carrying sound signals (i.e. white noise) and visual stimuli (i.e. abstract colour samples) and to limit visual and auditory contextual information. Participants were asked to evaluate noise annoyance on an 11-point International Commission on Biological Effects of Noise (ICBEN) scale. The experiments were conducted in the form of audio-visual tests. During these tests, random combinations of three white noise sound samples with sound pressure levels of 66 dB(A) (−4 dB[A] acoustic condition), 70 dB(A) (0 dB[A] acoustic condition) and 74 dB(A) (+4 dB[A] acoustic condition), and six visual stimuli, including the elementary colours of the Natural Colour System (NCS)—yellow (Y), red (R), blue (B), green (G), white (W) and black (S)—were presented to a total of 42 participants. The black colour sample was used to measure the audio-only control condition for the three white noise sound samples. The results of the study reveal that the effects of sound, the effects of colour and the interaction effects of colour and sound on perceived noise annoyance were statistically significant. The effects of colour on the loudness evaluations of the previous studies and the effects of colour on noise annoyance evaluations presented in this study show very similar and concordant results, indicating that the effects of colour on noise annoyance depend on the sound pressure level (SPL). The results indicate that the hue contrasts of red–green, red–blue and yellow–blue and the lightness contrast of yellow–blue influenced perceived noise annoyance when the SPL was low or high. Within the contrast pairs, red and yellow were perceived to be annoying, whereas blue and green were perceived to be non-annoying.

Weakened Cochlear Nonlinearity During Human Aging and Perceptual Correlates.

As humans age, compressive nonlinearity-a hallmark of healthy cochlear function-changes. The nonlinear distortion-component of the distortion product otoacoustic emission (DPOAE) provides a noninvasive gauge of cochlear nonlinearity. Earlier published work has suggested that weakened nonlinearity begins in middle age; the current work extends this investigation into the eight decade of life using advanced DPOAE data collection and analysis methods as well as multiple metrics of nonlinearity, including a test of loudness scaling. The 2f1-f2 DPOAE was recorded in 20 young adults, 25 middle-aged adults and 32 older adults from f2 = 0.78 to 9.4 kHz with primary tones (f2/f1 = 1.22) swept upward at a rate of 0.5 octave/sec. Only frequencies with audiometric thresholds ≤20 dB HL were included in the analysis and to the extent possible, ears were audiometrically matched to eliminate hearing threshold as a contributing factor to the observed age effects. Input/output functions were generated for the separated distortion-component of the DPOAE to probe compressive nonlinearity of the cochlea, and ipsilateral suppression of the DPOAE was conducted to probe two-tone suppression. To investigate the perceptual effects of weakening nonlinearity on loudness perception, the same subjects performed categorical loudness scaling. Age effects on both DPOAE and loudness scaling variables were assessed, and correlations were conducted between key OAE and perceptual metrics. Age × Frequency ANOVAs revealed that the compression knee of the DPOAE I/O function occurred at higher stimulus levels in both groups of older adults compared to young adults, suggesting an expanded linear range with aging; also, the compressive slope (growth beyond the knee point) was steeper in older-adults compared to young adults. These results were most notable at high frequencies. ANOVAs including age and auditory threshold as factors confirmed that the age effect observed was independent of threshold. Additionally, in smaller subsets of subjects with audiometrically matched data, these same trends persisted, further ruling out hearing threshold as an influential factor. The growth of DPOAE ipsilateral suppression was shallower near 4 kHz in middle-aged and older adults compared to young adults and elevated suppression thresholds were observed. Results of categorical loudness scaling showed steeper growth of loudness for older adults and, at fixed sensation levels (dB SL), the older-adult group rated tones as louder than did their young-adult counterparts, suggesting abnormal loudness growth and perception. Several correlations between the compression knee of the DPOAE I/O function and key metrics of loudness scaling were significant and accounted for up to one-third of the variance. Results indicate that the aging cochlea begins to show weakened nonlinearity in middle age and it progressively weakens further into senescence. The perceptual impact of weakened nonlinearity during aging is manifested as abnormal loudness judgments; that is, in older-adult ears, a tone considered comfortable or medium in young-adult ears can be considered loud. The biophysical origin of this weakened nonlinearity is not known. It is hypothesized to reflect aging-related damage to, or loss of, outer hair cells and their stereocilia. More work is warranted to better define the perceptual impact of a linearized cochlear response in older adults and to consider how this deficit might impact the fitting of hearing aids and other intervention strategies.

Contextual effects on loudness judgments for sounds with continuous changes of intensity are reflected in nonauditory areas.

Psychoacoustic research suggests that judgments of perceived loudness change differ significantly between sounds with continuous increases and decreases of acoustic intensity, often referred to as “up‐ramps” and “down‐ramps.” The magnitude and direction of this difference, in turn, appears to depend on focused attention and the specific task performed by the listeners. This has led to the suspicion that cognitive processes play an important role in the development of the observed context effects. The present study addressed this issue by exploring neural correlates of context‐dependent loudness judgments. Normal hearing listeners continuously judged the loudness of complex‐tone sequences which slowly changed in level over time while auditory fMRI was performed. Regression models that included information either about presented sound levels or about individual loudness judgments were used to predict activation throughout the brain. Our psychoacoustical data confirmed robust effects of the direction of intensity change on loudness judgments. Specifically, stimuli were judged softer when following a down‐ramp, and louder in the context of an up‐ramp. Levels and loudness estimates significantly predicted activation in several brain areas, including auditory cortex. However, only activation in nonauditory regions was more accurately predicted by context‐dependent loudness estimates as compared with sound levels, particularly in the orbitofrontal cortex and medial temporal areas. These findings support the idea that cognitive aspects contribute to the generation of context effects with respect to continuous loudness judgments.

Influence of Measurement Procedure on the Korean Matrix Sentence-in-Noise Intelligibility for Normal-Hearing Listeners

Background and Objectives A Korean Matrix Sentence Test is one of the adaptive tests used to evaluate speech intelligibility in noise. The present study aimed to investigate the influence of measurement procedure (presentation level and mode) on the Korean matrix sentence-in-noise intelligibility of normal-hearing listeners.Subjects and Method Twenty-seven normal-hearing adults participated in the study. The speech reception threshold (SRT) was determined using a software-based adaptive procedure, which converges on the signal-to-noise ratio (SNR), corresponding to 50% intelligibility. The speech or speech-shaped noise was given at three presentation levels based on the previous categorical loudness judgments (between soft and medium: 55 dB SPL, medium: 65 dB SPL, and loud level: 80 dB SPL). The effect of the presentation mode was explored by fixing either the sentence level or noise level, while the noise or sentence level was adaptively adjusted according to the subject’s response.Results The presentation level significantly affected the SRTs, whereas the SRTs did not depend on the presentation mode. The sentence-in-noise intelligibility was similar between 55 and 65 dB SPL, yet the sentence-in-noise intelligibility significantly decreased at 80 dB SPL regardless of the presentation mode. Correlation analyses showed moderate to high positive correlations among the results of two presentation modes.Conclusion A presentation level of 55 or 65 dB SPL yielded comparable adaptive measurement results for normal-hearing subjects, yet the sentence-in-nose intelligibility became worse at 80 dB SPL. Clinicians should be careful with the influence of the presentation level when identifying speech-in-noise intelligibility.

Subjective criteria underlying noise-tolerance in the presence of speech

Objective The objective was to determine the relative contribution of four criteria (loudness, annoyance, distraction, speech interference) to participants’ noise-tolerance thresholds (NTT). Design While listening to speech in noise set at the highest signal-to-noise ratio at which noise became unacceptable (noise tolerance threshold), participants completed paired-comparison judgments of loudness, annoyance, distraction, and speech interference to determine the noise domain(s) that were most important in their noise tolerance judgments. Participants also completed absolute ratings of the noise using the same noise domains, which were combined with the paired comparison data for analysis. Study Sample Sixty-three adults with normal hearing participated. Results For the entire group, speech interference and distraction were the largest contributors to noise tolerance. A cluster analysis indicated three distinct groups: criteria were dominated by either annoyance (33%); distraction (48%), or speech interference (19%). Significant differences in NTT among the groups revealed the highest mean NTT for the annoyance group and lowest NTT for the speech interference group. Conclusion The majority of participants based NTTs on criteria related to the noise itself (annoyance or distraction) and had greater noise sensitivity than the smaller group of participants who focused more on speech intelligibility in the noise.

The effect of silent gaps on temporal weights in loudness judgments

Human loudness judgments of time-varying sounds show a non-uniform temporal weighting pattern with increased weights at the beginning of a sound. Four experiments were conducted to investigate whether this primacy effect reoccurs after a silent gap of an appropriate duration that is inserted into a level-fluctuating sound. In three of the experiments, contiguous sounds as well as sounds containing silent gaps of different durations were presented. The temporal loudness weights were compared between the sounds that contained a gap and the sounds without a gap. The data showed that with increasing gap duration an increasingly pronounced primacy effect reoccurred on the second sound part in the sense that a) the weights assigned to the first segments after the gap were increased compared to the conditions without a gap, and that b) the following weights again showed a decrease over time. This effect was statistically significant for gap durations of 350 ms and above. To investigate whether an attenuation in level can lead to the same results as a silent gap, segments in the middle part of a sound were attenuated in the fourth experiment, and the resulting weights were compared to conditions in which the middle segments were unattenuated or where a 700 ms silent gap was presented instead of the middle segments. An attenuation of 15 dB resulted in a significant reoccurrence of the primacy effect, although the effect was more pronounced for an attenuation of 30 dB and the silent gap. The results are discussed in the light of auditory nerve responses, masking effects on intensity resolution, and assumptions based on evidence integration processes.

Using auditory reaction time to measure loudness growth in rats

Previous studies have demonstrated that auditory reaction time (RT) is a reliable surrogate of loudness perception in humans. Reaction time-intensity (RT-I) functions faithfully recapitulate equal loudness contours in humans while being easier to obtain than equal loudness judgments, especially in animals. In humans, loudness estimation not only depends on sound intensity, but on a variety of other acoustic factors. Stimulus duration and bandwidth are known to impact loudness perception. In addition, the presence of background noise mimics loudness recruitment; loudness growth is rapid near threshold, but growth becomes normal at suprathreshold levels. Therefore, to evaluate whether RT-I functions are a reliable measure of loudness growth in rats, we obtained auditory RTs across a range of stimulus intensities, durations, and bandwidths, in both quiet and in the presence of background/masking noise. We found that reaction time patterns across stimulus parameters were repeatable over several months in rats and generally consistent with human loudness perceptual data. Our results provide important building blocks for future animal model studies of loudness perception and loudness perceptual disorders.

Comparison of Relative Loudness Judgment in Children using Listening Devices with Typically Developing Children.

Introduction Loudness perception is considered important for the perception of emotions, relative distance and stress patterns. However, certain digital hearing devices worn by those with hearing impairment may affect their loudness perception. This could happen in devices that have compression circuits to make loud sounds soft and soft sounds loud. These devices could hamper children from gaining knowledge about loudness of acoustical signals. Objective To compare relative loudness judgment of children using listening devices with age-matched typically developing children. Methods The relative loudness judgment of sounds created by day-to-day objects were evaluated on 60 children (20 normal-hearing, 20 hearing aid users, & 20 cochlear implant users), utilizing a standard group comparison design. Using a two-alternate forced-choice technique, the children were required to select picturized sound sources that were louder. Results The majority of the participants obtained good scores and poorer scores were mainly obtained by children using cochlear implants. The cochlear implant users obtained significantly lower scores than the normal-hearing participants. However, the scores were not significantly different between the normal-hearing children and the hearing aid users as well as between the two groups with hearing impairment. Conclusion Thus, despite loudness being altered by listening devices, children using non-linear hearing aids or cochlear implants are able to develop relative loudness judgment for acoustic stimuli. However, loudness growth for electrical stimuli needs to be studied.

Activation in human auditory cortex in relation to the loudness and unpleasantness of low-frequency and infrasound stimuli

Low frequency noise (LFS) and infrasound (IS) are controversially discussed as potential causes of annoyance and distress experienced by many people. However, the perception mechanisms for IS in the human auditory system are not completely understood yet. In the present study, sinusoids at 32 Hz (at the lower limit of melodic pitch for tonal stimulation), as well as 8 Hz (IS range) were presented to a group of 20 normal hearing subjects, using monaural stimulation via a loudspeaker sound source coupled to the ear canal by a long silicone rubber tube. Each participant attended two experimental sessions. In the first session, participants performed a categorical loudness scaling procedure as well as an unpleasantness rating task in a sound booth. In the second session, the loudness scaling procedure was repeated while brain activation was measured using functional magnetic resonance imaging (fMRI). Subsequently, activation data were collected for the respective stimuli presented at fixed levels adjusted to the individual loudness judgments. Silent trials were included as a baseline condition. Our results indicate that the brain regions involved in processing LFS and IS are similar to those for sounds in the typical audio frequency range, i.e., mainly primary and secondary auditory cortex (AC). In spite of large variation across listeners with respect to judgments of loudness and unpleasantness, neural correlates of these interindividual differences could not yet be identified. Still, for individual listeners, fMRI activation in the AC was more closely related to individual perception than to the physical stimulus level.

Contribution of frequency bands to the loudness of broadband sounds: Tonal and noise stimuli.

Contributions of individual frequency bands to judgments of total loudness can be assessed by varying the level of each band independently from one presentation to the next and determining the relation between the change in level of each band and the loudness judgment. In a previous study, measures of perceptual weight obtained in this way for noise stimuli consisting of 15 bands showed greater weight associated with the highest and lowest bands than loudness models would predict. This was true even for noise with the long-term average speech spectrum, where the highest band contained little energy. One explanation is that listeners were basing decisions on some attribute other than loudness. The current study replicated earlier results for noise stimuli and included conditions using 15 tones located at the center frequencies of the noise bands. Although the two types of stimuli sound very different, the patterns of perceptual weight were nearly identical, suggesting that both sets of results are based on loudness judgments and that the edge bands play an important role in those judgments. The importance of the highest band was confirmed in a loudness-matching task involving all combinations of noise and tonal stimuli.

Determination of preference-equivalent levels for fan noise and their prediction by indices based on specific loudness patterns.

In a previous study by the authors, two indices were identified as appropriate descriptors for perceptual dimensions of fan noise. The index Nlow describes the amount of low-frequency loudness relative to the overall loudness. The index Nratio represents the ratio between the amount of loudness resulting from mid-frequency content and that from high frequencies. The aim of this study is to quantify how variations in these two indices affect subjects' preferences and loudness judgments. In listening experiments, fan noise signals were adjusted separately to equal loudness and equal preference compared to a common reference sound by varying their level in an adaptive procedure. The fan noises used in the listening tests consisted of 11 typical signals from three major groups of fan sounds from the earlier study and 18 signals that were parametrically varied in terms of the two indices. Reductions in A-weighted sound pressure level of up to 15 dB were necessary to make unpleasant fan sounds equally preferred as the fixed reference sound. A regression model based on the index Nratio explains 81% of the variation in the evaluation data with a root-mean-squared error of 2.53 dB.

Group Means and Intersubject and Intrasubject Variability Estimates for Absolute and Relative (Categorical) Loudness Judgments of Typical Young Adult Listeners

Purpose This brief research note is motivated by an ever-increasing need for typical repeated-measures loudness judgments and variability estimates of the kind necessary to conduct evidence-based treatment studies and clinical trials. Method These judgments and variability data, originally collected but not reported by Formby, Payne, Yang, Wu, and Parton (2017) , are presented here for relative (categorical) and absolute loudness judgments for typical young adult listeners with normal auditory function. Results As shown in this research note, these data may differ appreciably between young and older adult listeners with audiometric pure-tone thresholds within the clinically normal range. Conclusion In general, these findings highlight the need for good age-based, repeated-measures data for planning and powering evidence-based treatment studies and, specifically, for clinical trials that rely on categorical loudness judgments (i.e., as measured with the Contour Test of loudness; Cox, Alexander, Taylor, & Gray, 1997 ) as primary and secondary outcome measures.