Loudness Judgments Research Articles

CI Programming in Patients with Neurologic Impairment

CI Programming in Patients with Neurologic Impairment

Evaluation of a model of temporal weights in loudness judgments.

The onset of a sound receives a higher weight than later portions in time when its loudness is assessed, an effect commonly referred to as primacy effect. It is investigated if this effect can be predicted on the basis of an exponentially decaying function where the weight assigned to a temporal portion of a sound is the integral of this function over the segment duration. To test this model, temporal loudness weights were measured for sounds with different segment durations and total durations. The model successfully predicted essential aspects of the data.

Interrelationships among microstructures of otoacoustic emissions and hearing thresholds

Otoacoustic emission (OAE) amplitudes, phases, and delays often exhibit ripples with small changes in stimulus frequency. Similar microstructure patterns are observed in behavioral hearing thresholds and loudness judgements for pure tones. Here, we summarize work demonstrating that there is a common microstructure in hearing thresholds and OAEs elicited by single tones—referred to as stimulus-frequency OAEs (SFOAEs)—when presented at near-threshold levels. The periodicity and strength of this microstructure are related to SFOAE delay and magnitude, respectively. Such relationships are consistent with this microstructure arising from multiple intracochlear reflections of SFOAE energy between its region of generation and the middle ear boundary—an idea proposed by David Kemp in his first reports describing the discovery of emissions from the ear. The details of OAE generation and propagation explain why similar but not identical microstructures are also observed in the ear canal pressure in response to tones (which is the vector sum of the stimulus and SFOAE pressures) and in two-tone evoked distortion-product OAE spectra, as well as why microstructures shift in frequency as the result of cochlear or middle ear manipulations.Otoacoustic emission (OAE) amplitudes, phases, and delays often exhibit ripples with small changes in stimulus frequency. Similar microstructure patterns are observed in behavioral hearing thresholds and loudness judgements for pure tones. Here, we summarize work demonstrating that there is a common microstructure in hearing thresholds and OAEs elicited by single tones—referred to as stimulus-frequency OAEs (SFOAEs)—when presented at near-threshold levels. The periodicity and strength of this microstructure are related to SFOAE delay and magnitude, respectively. Such relationships are consistent with this microstructure arising from multiple intracochlear reflections of SFOAE energy between its region of generation and the middle ear boundary—an idea proposed by David Kemp in his first reports describing the discovery of emissions from the ear. The details of OAE generation and propagation explain why similar but not identical microstructures are also observed in the ear canal pressure in response to tone...

How does the perceptual organization of a multi-tone mixture interact with partial and global loudness judgments?

Two experiments were conducted to investigate how the perceptual organization of a multi-tone mixture interacts with global and partial loudness judgments. Grouping (single-object) and segregating (two-object) conditions were created using frequency modulation by applying the same or different modulation frequencies to the odd- and even-rank harmonics. While in Experiment 1 (Exp. 1) the two objects had the same loudness, in Experiment 2 (Exp. 2), loudness level differences (LLD) were introduced (LLD = 6, 12, 18, or 24 phons). In the two-object condition, the loudness of each object was not affected by the mixture when LLD = 0 (Exp. 1), otherwise (Exp. 2), the loudness of the softest object was modulated by LLD, and the loudness of the loudest object was the same regardless of whether it was presented in or out of the mixture. In the single- and the two-object conditions, the global loudness of the mixture was close to the loudness of the loudest object. Taken together, these results suggest that while partial loudness judgments are dependent on the perceptual organization of the scene, global loudness is not. Yet, both partial and global loudness computations are governed by relative "saliences" between different auditory objects (in the segregating condition) or within a single object (in the grouping condition).

Quantification of Preference Relevant Sound Characteristics of Multi-Tone Sounds Based on the Differences Between Loudness Judgments and Preference Evaluations

Quantification of Preference Relevant Sound Characteristics of Multi-Tone Sounds Based on the Differences Between Loudness Judgments and Preference Evaluations

Overall judgment of loudness of time-varying sounds.

Listeners can judge the overall loudness of time-varying sounds quite easily, i.e., assign a single value that represents the loudness of the entire sound. This holds even if the duration is long and the judgment includes memory effects. Different metrics for calculating overall loudness have been developed. They agree that overall loudness is higher than the mean of loudness over time. Percentiles like the N5, the loudness being exceeded 5% of the time, are adopted by ISO 532-1. In the present study the concept of an energy mean known from level measurements (ISO 1996-1) was applied to the loudness domain. This equivalent continuous loudness level, LLP, was compared to the N5 using a set of real-world sounds that was orthogonal between the two metrics over a wide dynamic range of 30 phon. Cross-modality matching with line length was used in three experiments with a focus on either the overall judgment of loudness, continuous judgment while a sound was played, or both. The LLP showed considerably higher correlations with overall judgments than N5. Comparing continuous instantaneous judgment with calculated instantaneous loudness suggests that the participants might have focused on the sounds' prominent portions.

Loudness counts: Interactions between loudness, number magnitude, and space.

ATOM (a theory of magnitude) suggests that magnitude information of different formats (numbers, space, and time) is processed within a generalized magnitude network. In this study we investigated whether loudness, as a possible indicator of intensity and magnitude, interacts with the processing of numbers. Small and large numbers, spoken in a quiet and a loud voice, were simultaneously presented to the left and right ear (Experiments 1a and 1b). Participants judged whether the number presented to the left or right ear was louder or larger. Responses were faster when the smaller number was spoken in a quiet voice, and the larger number in a loud voice. Thus, task-irrelevant numerical information influenced the processing of loudness and vice versa. This bi-directional link was also confirmed by classical SNARC paradigms (spatial-numerical association of response codes; Experiments 2a-2c) when participants again judged the magnitude or loudness of separately presented stimuli. In contrast, no loudness-number association was found in a parity judgment task. Regular SNARC effects were found in the magnitude and parity judgment task, but not in the loudness judgment task. Instead, in the latter task, response side was associated with loudness. Possible explanations for these results are discussed.

Global loudness of rising- and falling-intensity tones: How temporal profile characteristics shape overall judgments

The mechanisms underlying global loudness judgments of rising- or falling-intensity tones were further investigated in two magnitude estimation experiments. By manipulating the temporal characteristics of such stimuli, it was examined whether judgments could be accounted for by an integration of their loudest portion over a certain temporal window associated to a "decay mechanism" downsizing this integration over time for falling ramps. In experiment 1, 1-kHz intensity-ramps were stretched in time between 1 and 16 s keeping their dynamics (difference between maximum and minimum levels) unchanged. While global loudness of rising tones increased up to 6 s, evaluations of falling tones increased at a weaker rate and slightly decayed between 6 and 16 s, resulting in significant differences between the two patterns. In experiment 2, ramps were stretched in time between 2 and 12 s keeping their slopes (rate of change in dB/s) unchanged. In this context, the main effect of duration became non-significant and the interaction between the two profiles remained, although the decay of falling tones was not significant. These results qualitatively support the view that the global loudness computation of intensity-ramps involves an integration of their loudest portions; the presence of a decay mechanism could, however, not be attested.

Effect of hearing loss on spectral weighting of broadband signals

Several studies have shown that normal hearing (NH) listeners place greater weight on the edge frequencies of broadband sounds when they are asked to pick the louder of two intervals in a sample discrimination task. However, little is known about the effects of hearing loss on spectral weighting for broadband sounds. In a classic study of sample discrimination, Doherty and Lutfi (1996) found that listeners with hearing loss (HL) placed greater weight on frequencies in the region of the HL and proposed that components that were less audible were weighted higher. The current study investigated the effect of audibility and hearing loss on spectral weighting for loudness judgments using two spectrally overlapping 18-tone complexes (from 208- to 8708-Hz). Four NH and nine HL listeners judged the loudness of tone complexes in two conditions where the mean level of each tone in the complex was set to either 10-dB SL or 75-dB SPL. The results show that listeners placed greater weight on the high-frequency edges of both tone complexes in 10-dB SL condition but not in 75-dB SPL condition, suggesting that the HL listeners place less weight on portions of the spectrum near the threshold of audibility. [Work supported by NIH.]

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.

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 soft and loud, but OK 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 very soft to uncomfortably loud 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 soft and loud, but OK 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 soft and for loud, but OK 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 soft and for loud, but OK 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 soft and loud, but OK 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 soft (audible), comfortable, and loud, but OK (tolerable) sound inputs for the individual listener.

Relations among Auditory Brainstem and Middle Latency Response Measures, Categorical Loudness Judgments, and Their Associated Physical Intensities.

This study characterizes changes in response properties of toneburst-evoked auditory brainstem responses (ABRs) and/or middle latency responses (MLRs) as a function of perceived loudness and physical intensity of these stimuli and delineates the range of levels corresponding to categorical loudness judgments for these stimuli. ABRs/MLRs were recorded simultaneously to 500- and 2,000-Hz tonebursts in 10 normal-hearing adults at levels corresponding to each listener's loudness judgments for four categories on Contour Test of Loudness. Group mean ABR wave V and MLR wave Pa latency values increased significantly as loudness judgments decreased. Group mean amplitude values for ABR wave V-V' and MLR wave Na-Pa increased as the listeners' categorical judgments increased. Listeners assigned a broad range (30 to 40 dB) of stimulus intensities when judging loudness of these stimuli within a specific loudness category. This was true for all four loudness categories and both frequencies. Thus, it appears that tone-evoked ABR/MLR response measures reflect, in part, the listener's perception of loudness. Response latencies are a more sensitive indicator of listener's loudness percept than corresponding response amplitudes. An appreciable range of signal levels was judged to be categorically equivalent across listeners. Thus, limiting how loudness judgments can be applied to prescriptive hearing aid fittings in individuals who cannot provide accurate loudness judgments.

Intra- and Intersubject Variability in Audiometric Measures and Loudness Judgments in Older Listeners with Normal Hearing.

This research was to document intra- and intersubject variability in measures of pure tone thresholds, loudness discomfort levels, and the Contour test of loudness for tonal and speech stimuli across 8 to 10 repeated test sessions over a period of almost 1 year in a group of 11 normal-hearing, older middle-aged adults (39 to 73 years, mean of 56 years). The measured pure tone thresholds and loudness discomfort levels were determined to be stable across sessions, with variability on the order of 5 dB. The categorical judgments for the Contour test for both warbled tones and spondaic speech stimuli decreased over time in level required for categories greater than comfortable. This result contrasts with reports of a slight increase over time when young, normal-hearing adults were tested in comparable measures. The intrasubject variability in the Contour test results was greatest for the 4,000-Hz tonal stimulus for which the largest time effects were observed. The intersubject variability was typically greater than the intrasubject variability and typically increased as the loudness category increased, with some exceptions. The results from this study can be used to aid in power and sample size analyses using these measures in future studies designed to compare effects of treatments based on changes in loudness judgments over time.

Structured Counseling for Auditory Dynamic Range Expansion.

A structured counseling protocol is described that, when combined with low-level broadband sound therapy from bilateral sound generators, offers audiologists a new tool for facilitating the expansion of the auditory dynamic range (DR) for loudness. The protocol and its content are specifically designed to address and treat problems that impact hearing-impaired persons who, due to their reduced DRs, may be limited in the use and benefit of amplified sound from hearing aids. The reduced DRs may result from elevated audiometric thresholds and/or reduced sound tolerance as documented by lower-than-normal loudness discomfort levels (LDLs). Accordingly, the counseling protocol is appropriate for challenging and difficult-to-fit persons with sensorineural hearing losses who experience loudness recruitment or hyperacusis. Positive treatment outcomes for individuals with the former and latter conditions are highlighted in this issue by incremental shifts (improvements) in LDL and/or categorical loudness judgments, associated reduced complaints of sound intolerance, and functional improvements in daily communication, speech understanding, and quality of life leading to improved hearing aid benefit, satisfaction, and aided sound quality, posttreatment.

Using acoustic reflex threshold, auditory brainstem response and loudness judgments to investigate changes in neural gain following acute unilateral deprivation in normal hearing adults

Unilateral auditory deprivation induces a reduction in the acoustic reflex threshold (ART) and an increase in loudness. These findings have been interpreted as a compensatory change in neural gain, governed by changes in excitatory and inhibitory neural inputs. There is also evidence to suggest that changes in neural gain can be measured using the auditory brainstem response (ABR). The present study extended Munro et al. (2014) [J. Acoust. Soc. Am. 135, 315–322] by investigating changes after 4 days of unilateral earplug use to: (i) ART, (ii) ABR and (iii) loudness. Because changes may occur during the post-deprivation test session (day 4), ART measurements were taken 1 h and 2 h post-earplug removal. There was a significant reduction in ART in the treatment ear immediately after the removal of the earplug, which is consistent with a compensatory increase in neural gain. A novel finding was the significant return of ARTs to baseline within 2 h of earplug removal. A second novel finding was a significant decrease in the mean amplitude of ABR wave V in the treatment ear, but a significant increase in the control ear, both after 4 days of deprivation. These changes in the ABR are in the opposite direction to those predicted. We were unable to replicate the change in loudness reported in previous deprivation studies; however, the short period of earplug use may have contributed to this null finding.

精神物理学と音色

G. T. Fechner proposed his logarithmic law between physical continuum of stimulus and an attribute of sensation in 1860. Fechner also proposed the distinction between outer and inner-psychophysics. Outer-psychophysics deals with the relation between the observable participant's response and stimulus. In outer-psychophysics, it can be postulated that the response is located on the interval scale when the logarithmic law between stimulus and response is established. In inner-psychophysics, the logarithmic law is established in mind on the assumption that the equality of subjective size of just noticeable difference (jnd). However, it is difficult to verify the equality of jnd using empirical procedures. Bergson strongly criticizes that Fechner's law is based on an assumption that cannot be verified. Zwislocki (1991) defines that the measurement entails matching of common attributes of things or events. According to his definition of “Natural Measurement”, we can match the different things or events on the common psychological continuum. As a result, matching operation can ensure the point of subjective equality (PSE) to be a common attribute among different objects. When an appropriate measure is applied, the same PSE from different things or events confirms the same point on the continuum of common attribute of sensation. The PSE is a physical measure. It can be measured using objective or empirical procedure. An important role of psychophysics is to find an appropriate physical measure. Usually, the standardized physical measure of adequate stimulus is modified on the basis of psychophysical data and reflects the characteristics of sensation. Therefore, a good relationship between subjective response to adequate stimulus and a standardized measure can be expected. It is true that the relation between the loudness judgment of various kinds of nonsteady sounds and a standardized index (e. g. equivalent continuous A-weighted sound pressure level: LAeq) exhibits a high coefficient correlation. However, a law derived from the experimental results depends on the psychophysical method used. For example, the method of category scaling results logarithmic law and magnitude estimation results power law. The result of the experiment using the scale discriminative method was introduced to verify whether the logarithmic law or the power law was valid for the loudness judgment. The results showed that participants' quantitative judgments were well adapted to the experimental procedure. Torgerson (1960) suggests that the participants seem to judge the stimulus taking a different strategy depending on the purpose of the experiment. In daily life situations, we are very adaptive to quantitative behavior for satisfying the purpose of the behavior. This poses a problem of ecological validity in psychophysics. Therefore, it is necessary to select the appropriate stimuli and method to simulate the daily life situations in the psychophysical experiments. Main attributes of auditory sensation are loudness, pitch and timbre. Both loudness and pitch are one dimensional, but timbre or tone quality is multidimensional. It is difficult to constitute rating scale of tone quality expressed by only one physical dimension, and at present, it is far from to establish a general psychophysical rule for applying to tone quality. However, if the sound source is limited, a possibility of establishing a physical scale to predict tone quality. Some examples of the machine sound's tone quality control were introduced.

Effects of spectral gaps on the contribution of specific frequency bands to the loudness of broadband sounds

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. Recent studies using stimuli consisting of 15 bands of noise, each two critical bands wide, have shown that frequencies near the lower and upper edges of a broadband noise make a greater contribution to overall loudness than frequencies in the center of the spectrum. In the present study, eight listeners with normal hearing compared the loudness of two 15-band stimuli with average levels of 59 dB SPL per band and of stimuli where 1, 3, 5, or 7 bands were missing from the center of the spectrum. Listeners placed greater weight on the bands at the edges of the spectral gap and the effect was larger for greater gap widths. Edge bands received more weight regardless of absolute frequency and the high-frequency edge of the low bands received greater weight than the low-frequency edge of the high bands. These effects are not predicted by loudness models. [Work supported by NIH.]

Influence of simultaneous grouping mechanisms in the loudness judgment of a multi-tone mixture

Our main concern is to understand how the perceptual organization of an acoustical mixture into distinct auditory objects (known as an ASA mechanism) can affect the judgments of loudness. Three main questions have been raised: Is the loudness of one auditory object influenced by concurrent objects? How the partial loudness of different auditory objects are combined into one global loudness percept? Does global loudness depend on the perceptual organization of the mixture? In the present experiment, the mixtures consisted of frequency-modulated harmonic complexes. The same or different modulation frequencies have been applied to the odd and even harmonics to ensure that participants perceived either one or two auditory objects, respectively. As a first result, when two objects were well segregated (without spectral masking), the loudness of one object in the mixture equaled the loudness of the same object presented alone. It suggests that spectral grouping mechanisms prevail over loudness. Then, the global loudness pattern obtained for two auditory objects as a function of their partial loudness will be drawn up. Global loudness modeling for two auditory objects will be discussed with regards to the predictions given by classical loudness models. [Research supported by the chair “MOUVIE”, carried by the UPMC.]

The representation of level and loudness in the central auditory system for unilateral stimulation

Loudness is the perceptual correlate of the physical intensity of a sound. However, loudness judgments depend on a variety of other variables and can vary considerably between individual listeners. While functional magnetic resonance imaging (fMRI) has been extensively used to characterize the neural representation of physical sound intensity in the human auditory system, only few studies have also investigated brain activity in relation to individual loudness. The physiological correlate of loudness perception is not yet fully understood. The present study systematically explored the interrelation of sound pressure level, ear of entry, individual loudness judgments, and fMRI activation along different stages of the central auditory system and across hemispheres for a group of normal hearing listeners. 4-kHz-bandpass filtered noise stimuli were presented monaurally to each ear at levels from 37 to 97dB SPL. One diotic condition and a silence condition were included as control conditions. The participants completed a categorical loudness scaling procedure with similar stimuli before auditory fMRI was performed. The relationship between brain activity, as inferred from blood oxygenation level dependent (BOLD) contrasts, and both sound level and loudness estimates were analyzed by means of functional activation maps and linear mixed effects models for various anatomically defined regions of interest in the ascending auditory pathway and in the cortex. Our findings are overall in line with the notion that fMRI activation in several regions within auditory cortex as well as in certain stages of the ascending auditory pathway might be more a direct linear reflection of perceived loudness rather than of sound pressure level. The results indicate distinct functional differences between midbrain and cortical areas as well as between specific regions within auditory cortex, suggesting a systematic hierarchy in terms of lateralization and the representation of level and loudness.11A preliminary report on this study was presented during the 17th International Symposium on Hearing in Paterswolde, NL (Behler and Uppenkamp, 2016).

Balancing current levels in children with bilateral cochlear implants using electrophysiological and behavioral measures

Children have benefited from bilateral cochlear implants (CIs) over unilateral CIs despite often missing important periods in bilateral auditory development. This suggests a remarkable perceptual ability by children to “work around” abnormal changes in the auditory pathways. Nonetheless, these children rely primarily on interaural level differences as interaural timing cues are more difficult to access or detect. Mismatched levels provided to the two implants could distort interaural level cues thus compromising the benefits of bilateral CI use. We asked whether “balanced” or “centered” perception of bilateral input can be predicted by physiological or behavioral measures. Twenty-four children who had used unilateral CIs for 9.21 ± 2.66 years prior to bilateral implantation participated. “Balanced bilateral levels” were identified by responses occurring with a probability of 50% on the right side of the head and 50% on the left in a two choice lateralization task. Loudness judgments of current presented unilaterally by each implant were measured on a continuous visual scale. Maximum wave eV amplitudes were evoked unilaterally by each implant and matched amplitudes were identified. Balanced bilateral levels were predicted within 10 Clinical Units (CU) in 9 of 13 (69%) children using matched wave eV amplitudes. Bilaterally balanced levels were reasonably predicted by similar loudness judgments (<10% difference between CIs) in only 6 of 13 (46%) children. Results indicate that matching amplitudes of physiological responses can produce a balanced perception of bilateral input despite unilateral strengthening of the auditory pathways and can potentially be used clinically to provide a first approximation of balance/centered levels.

Auditory fMRI of Sound Intensity and Loudness for Unilateral Stimulation.

We report a systematic exploration of the interrelation of sound intensity, ear of entry, individual loudness judgments, and brain activity across hemispheres, using auditory functional magnetic resonance imaging (fMRI). The stimuli employed were 4 kHz-bandpass filtered noise stimuli, presented monaurally to each ear at levels from 37 to 97 dB SPL. One diotic condition and a silence condition were included as control conditions. Normal hearing listeners completed a categorical loudness scaling procedure with similar stimuli before auditory fMRI was performed. The relationship between brain activity, as inferred from blood oxygenation level dependent (BOLD) contrasts, and both sound intensity and loudness estimates were analyzed by means of linear mixed effects models for various anatomically defined regions of interest in the ascending auditory pathway and in the cortex. The results indicate distinct functional differences between midbrain and cortical areas as well as between specific regions within auditory cortex, suggesting a systematic hierarchy in terms of lateralization and the representation of sensory stimulation and perception.