Loudness Judgments Research Articles

Magnitude judgments of loudness change for discrete, dynamic, and hybrid stimuli

Recent investigations of loudness change within stimuli have identified differences as a function of direction of change and power range (e.g., Canévet, Acustica, 62, 2136-2142, 1986; Neuhoff, Nature, 395, 123-124, 1998), with claims of differences between dynamic and static stimuli. Experiment 1 provides the needed direct empirical evaluation of loudness change across static, dynamic, and hybrid stimuli. Consistent with recent findings for dynamic stimuli, quantitative and qualitative differences in pattern of loudness change were found as a function of power change direction. With identical patterns of loudness change, only quantitative differences were found across stimulus type. In Experiment 2, Points of Subjective loudness Equality (PSE) provided additional information about loudness judgments for the static and dynamic stimuli. Because the quantitative differences across stimulus type exceed the magnitude that could be expected based upon temporal integration by the auditory system, other factors need to be, and are, considered.

A comparison of the temporal weighting of annoyance and loudness

The influence of single temporal portions of a sound on global annoyance and loudness judgments was measured using perceptual weight analysis. The stimuli were 900-ms noise samples randomly changing in level every 100 ms. For loudness judgments, Pedersen and Ellermeier [J. Acoust. Soc. Am. 123, 963-972 (2008)] found that listeners attach greater weight to the beginning and ending than to the middle of a stimulus. Qualitatively similar weights were expected for annoyance. Annoyance and loudness judgments were obtained from 12 listeners in a two-interval forced-choice task. The results demonstrated a primacy effect for the temporal weighting of both annoyance and loudness. However, a significant recency effect was observed only for annoyance. Potential explanations of these weighting patterns are discussed. Goodness-of-fit analysis showed that the prediction of annoyance and loudness can be improved by allowing a non-uniform weighting of single temporal portions of the signal, rather than assuming a uniform weighting as in measures like the energy-equivalent level (L(eq)). A second experiment confirmed that the listeners were capable of separating annoyance and loudness of the stimuli. Noises with the same L(eq) but different amplitude modulation depths were judged to differ in annoyance but not in loudness.

Factors affecting a loudness asymmetry in real-room reverberation.

Narrowband stimuli with envelopes that have a slow-attack and a fast-decay (S-F) are judged to be louder than temporally-reversed, equal-energy versions of the stimuli (i.e., fast-attack and slow-decay, or F-S). We have found that this perceived loudness asymmetry is also apparent with real-room reflection patterns using dichotic presentation of sounds processed with binaural room impulse responses. These findings are consistent with the idea that the energy in the decaying tails of stimuli is discounted from loudness judgments because they are perceptually attributed to room reverberation. These results might therefore arise from the same perceptual mechanism that compensates for reverberation in speech which seems to operate within but not between frequency bands. Here, we ask whether the loudness asymmetry is similarly a “band-by-band” mechanism using conditions where loudness comparisons are made between S-F and F-S stimuli that are in the same or in different frequency bands.

Perceived loudness of speech based on the characteristics of glottal excitation source

The impulse-like characteristic of glottal excitation in speech production is an important factor in the perception of loudness of speech signals. This characteristic is attributed to the abruptness of the closing phase in the glottal cycle. In this paper, an acoustic feature, called strength of excitation, is proposed to represent the impulse-like nature of excitation. The strength of excitation is derived from the linear prediction residual of speech signals, where the residual can be considered as an estimate of the source of excitation. Since the loudness of speech is perceived over one or more utterances of speech, it is hypothesized that the distribution of strength of excitation is indicative of the perceived loudness of speech. The distribution of strength of excitation is shown to distinguish between soft and loud utterances of speakers. The distribution can also help in discriminating between the loudness of two speakers. The loudness measure obtained using the distribution of the strength of excitation is in agreement with the subjective judgment of loudness of speech.

Measuring Tinnitus Loudness Using Constrained Psychophysical Scaling

We measured tinnitus loudness using a new method of psychophysical scaling with the aim of introducing a potentially useful new procedure to the literature. Fourteen adults reporting tinnitus were trained to use a standardized loudness scale, and then they used that response scale to assess loudness of nonstandard stimuli and of their tinnitus. We also measured tinnitus loudness and pitch using a computer-based matching procedure, and we measured the impact of tinnitus on daily living using the Tinnitus Handicap Inventory (THI; C. W. Newman, G. P. Jacobson, & J. B. Spitzer, 1996) for those 14 individuals and an additional 2 participants. Results and Conclusions Our 14 trained participants judged loudness similarly to normal hearing participants for pure tones at normal hearing, nontinnitus frequencies-implying that their judgments of tinnitus loudness were valid. Constrained scaling of tinnitus loudness yielded measurements that were substantially greater than the sensation level of sounds matched to tinnitus loudness. Our total of 16 participants fell into 2 groups on the basis of hearing loss, extent of abnormal loudness growth at the tinnitus frequency, and several aspects of tinnitus experience. Finally, as previously found, there was little correlation between tinnitus loudness, no matter how measured, and the impact of tinnitus on daily life as measured by the THI.

The role of temporal-masking patterns in the determination of subjective duration and loudness for ramped and damped sounds

The association between temporal-masking patterns, duration, and loudness for broadband noises with ramped and damped envelopes was examined. Duration and loudness matches between the ramped and damped sounds differed significantly. Listeners perceived the ramped stimuli to be longer and louder than the damped stimuli, but the outcome was biased by the stimulus context. Next, temporal-masking patterns were measured for ramped- and damped-broadband noises using three (0.5, 1.5, and 4.0 kHz) 10 ms probe tones presented individually at various temporal delays. Predictions of subjective duration derived from masking results underpredicted the matching results. Loudness estimates derived from models that assume persistence of neural activity after stimulus offset [Glasberg B. R., and Moore, B. C. J. (2002). "A model of loudness applicable to time-varying sounds," J. Audio. Eng. Soc. 50, 331-341; Chalupper, J., and Fastl, H. (2002) "Dynamic loudness model (DLM) for normal and hearing-impaired listeners," Acust. Acta Acust. 88, 378-386] were greater for ramped sounds than for damped sounds and were close to the average results obtained via the matching task. Differences in simultaneous-masked thresholds for these stimuli could not account for the loudness-matching results. Decay suppression of the later occurring portion of the damped stimulus may account for the differences in perception due to the stimulus context; however, a parsimonious implementation of this process that accounts for both subjective duration and loudness judgments remains unclear.

Does induced loudness reduction explain contextual effects in loudness judgment

Briefly presenting an inducing tone of 70‐80 dB can substantially reduce the loudness of a subsequent test tone at or near the inducer's frequency, a phenomenon called Induced Loudness Reduction (ILR). The study of ILR emerged from earlier observations on differential contextual effects in loudness judgment: Tones of a given SPL and frequency were judged softer when presented as part of an ensemble of high rather than low SPL tones at the same frequency, relative to judgments of loudness of tones at a different sound frequency. At first, these effects of stimulus context on loudness judgment were assumed to reflect decisional processes, that is, to reflect biases in loudness judgment. On the other hand, ILR is often assumed to reflect a depression in the intensity response of the auditory system. While it is tempting to explain differential contextual effects in loudness judgment wholly in terms of ILR, the properties of ILR and the properties of contextual effects may not be identical, leaving open a possible role for decisional processes as well as sensory processes in contextual effects, and perhaps also in ILR, in both laboratory and 'real‐world' settings.

Influence of vehicle color on loudness judgments

This experiment investigates the effect of images of differently colored sports cars on the loudness of a simultaneously perceived car sound. Still images of a sports car, colored in red, light green, blue, and dark green, were displayed to subjects during a magnitude estimation task. The sound of an accelerating sports car was used as a stimulus. Statistical analysis suggests that the color of the visual stimulus may have a small influence on loudness judgments. The observed loudness differences are generally equivalent to a change in sound level of about 1 dB, with maximum individual differences of up to 3 dB.

Auditory memory and evaluation of environmental sounds

A series of experiments were conducted concerning the memory of environmental sounds. Twelve kinds of sound were presented with soft background noise of about 6 min to participants. They were asked to recall or recognize the sound sources and to judge the loudness of the recalled or recognized sounds some period after they listened to the sounds. The recalled or recognized loudness was examined in relation to the length of the period between the presentation of sounds and the judgment of loudness, the method to measure the memory, LAeq of each sound source, etc. The results suggest that it is possible to judge the loudness of the memorized sounds and that the judgments seems reliable.

Loudness asymmetry ratings between accelerating and decelerating car sounds

Loudness change has been studied for tones with linearly varying levels revealing an asymmetry depending on the direction of change (increasing vs. decreasing) and the range of levels (high vs. low). Different assumptions were proposed to explain this asymmetry in favour of linearly increasing sounds. Teghtsoonian et al. (2005) and, more recently, Susini et al. (2006) explain that loudness of an increasing sound is influenced by the end level. Neuhoff (1999) describes this result by a survival advantage for detecting an approaching sound source. Whatever the assumption is, the results show that loudness judgments for abstract sounds (1000‐Hz tones) and synthetic vowel sounds were significantly higher for increasing ramps. Those results are compared here with continuous and global ratings obtained on everyday sounds such as accelerating and decelerating car sounds with a same duration (43 s), but with different temporal functions and range of levels. Global loudness judgments made after the end of the sound are significantly higher for accelerating than decelerating car sounds, but are judged on average similar using continuous judgments. In addition, an increase in the speed (acceleration) is evaluated primarily in terms of its level at the end. These results confirm the previous studies.

Effect of reverberation on loudness perception

Stimuli with a slow‐attack/fast‐decay (S‐F) envelope are judged to be louder than stimuli with a temporally‐reversed, equal‐energy version of the same envelope (fast‐attack/slow‐decay or F‐S). It may be that the energy in the tails of F‐S stimuli is discounted from loudness judgments because it is perceptually attributed to room reverberation. Here we examine the characteristics of real‐room reverberation that affect loudness perception, particularly the way that reverberant tails tend to be de‐correlated at the two ears. Our experiments used reverberation from real‐room measurements of binaural room impulse responses (BRIRs). We ask if the perceived reduction in loudness of F‐S stimuli relative to S‐F stimuli is still apparent with dichotic sounds processed by the BRIRs.

Temporal weighting in loudness judgments of time-varying sounds containing a gradual change in level

Two experiments studied how listeners weight the level information from different portions of a noise consisting of ten temporal segments, the levels of which were sampled independently from a normal distribution. If a gradual increase in level ("fade-in") is imposed on the first few segments in such a sound, temporal weights in global loudness judgments in a one-interval paradigm show a delayed primacy effect [Oberfeld and Plank, Fortschritte der Akustik - DAGA2005, 227-228 (2005)]. The maximum weight is assigned to the first segment presented at the full level, while the weights assigned to the fade-in segments are close to zero. In Experiment 1, a similar pattern of weights was observed in a two-interval paradigm. Thus, listeners do not use intensity information from the fade-in segments even when making within-trial comparisons. In Experiment 2, the first three segments gradually decreased rather than increased in level (i.e., the first segment had the highest level). Listeners gave near exclusive weight to the first segment. The results are compatible with a tendency to assign greater weight to loud elements [Lutfi and Jesteadt, J. Acoust. Soc. Am. 120, 3853-3860 (2006)] rather than with segmentation of the noise into a "gradually changing" and a "stable" part.

Are absolute thresholds and loudness judgements influenced by different colours

Previous experiments showed that images of differently colored trains and sports cars can influence the loudness ratings given by subjects via free magnitude estimation. Red vehicles caused subjects to rate the loudness of simultaneously presented train or car sounds higher relative to green vehicles. To investigate whether these loudness differences correspond to shifts in absolute threshold, subject's threshold in quiet was measured via Békésy-tracking while viewing red, green, and neutral color patches. Also, the influence of color on the loudness of broadband noise was measured using a method of adjustment, in which subjects had to adjust the level of a test sound until it was perceived as loud as a reference sound. In both cases, no influence of color on either absolute threshold or loudness perception measured via adjustment could be found. These results support the hypothesis that, compared to previously used methods like magnitude estimation, methods that require subjects to concentrate on the auditory stimulus do not seem to be as applicable for measurements of audio-visual interactions.

When exposed to sounds, would perceived loudness not be affected by social context

After decades of predominantly correlation studies of non-auditory factors and environmental noise annoyance, Maris, Stallen, Vermunt and Steensma (2007a,2007b) have demonstrated experimentally that a negative and positive relationship between producer and receiver of environmental sounds can cause the receiver to be more and less annoyed by the sound, respectively. This finding raises the question whether the context of environmental sound, and social context in particular, could already be determining responses to environmental sounds at earlier stages of auditory processing. This paper will present answers regarding perceived loudness, which is generally considered to be a more immediate (and less evaluative) response to sound exposure than the feeling of annoyance. From a statistics point of view, there is room for early influences as isophones which are based upon equal loudness judgments seem to hide no less, if not more, variation than the mean annoyance score at various sound pressure levels (cf. Berglund and Preis, 1997). It will be argued that seemingly conflicting empirical findings could be reconciled by postulating different attentional mechanisms as they vary with task characteristics and demands. Ideas will be presented by which the presumed theoretical model could be tested experimentally.

Does a rhythmic context have an effect on perceptual weights in auditory intensity processing?

The effects of a rhythmic context on auditory intensity processing were studied. Experiment 1 tested the hypothesis that the involuntary temporal direction of attention by a rhythmic context sequence influences the temporal weighting of loudness. Perceptual weight analysis was used to measure the attention directed to individual temporal portions of a longer stimulus by estimating the importance of individual temporal segments for global loudness judgements. A rhythmic context resulted in a sharper temporal weighting profile, but the expected rhythmic pattern of weights was not observed. In Experiment 2, the accuracy for detecting a peak in the temporal loudness profile of a level-fluctuating noise was measured for the level increment presented at expected and unexpected times. The rhythmic context again caused a more pronounced temporal weighting profile. However, the accuracy was neither significantly increased for expected target segment positions nor decreased for unexpected target segment positions, relative to the condition without a rhythmic context sequence.

Temporal weights in the level discrimination of time-varying sounds

To determine how listeners weight different portions of the signal when integrating level information, they were presented with 1-s noise samples the levels of which randomly changed every 100 ms by repeatedly, and independently, drawing from a normal distribution. A given stimulus could be derived from one of two such distributions, a decibel apart, and listeners had to classify each sound as belonging to the "soft" or "loud" group. Subsequently, logistic regression analyses were used to determine to what extent each of the ten temporal segments contributed to the overall judgment. In Experiment 1, a nonoptimal weighting strategy was found that emphasized the beginning, and, to a lesser extent, the ending of the sounds. When listeners received trial-by-trial feedback, however, they approached equal weighting of all stimulus components. In Experiment 2, a spectral change was introduced in the middle of the stimulus sequence, changing from low-pass to high-pass noise, and vice versa. The temporal location of the stimulus change was strongly weighted, much as a new onset. These findings are not accounted for by current models of loudness or intensity discrimination, but are consistent with the idea that temporal weighting in loudness judgments is driven by salient events.

Adaptive Recalibration of Chronic Auditory Gain

This report follows up and extends an exploratory investigation of a hypothetical adaptive chronic gain (amplification of suprathreshold information) process within the auditory system. In theory, this hypothetical gain process is plastic and can be systematically modified and recalibrated. The idea of an adaptive auditory gain mechanism is a fundamental concept in the treatment of both tinnitus and hyperacusis with tinnitus retraining therapy (TRT). This notion, however, has gone virtually untested. The hypothesis of this research is that judgments of loudness provide a functional index of chronic auditory gain. Further, chronic auditory gain can be manipulated either upward or downward in a controlled way by prolonged reduction or enhancement in the levels of background sound to which a listener is exposed. To evaluate these assertions, 8 normal-hearing volunteers were assigned randomly to continuous (23 hours/day), chronic (4-week) external sound treatments. Participants were exposed either to low-level sound produced by bilateral in-the-ear noise generators (NGs) or were fitted bilaterally with sound-attenuating earplugs (EPs) in a sequential crossover design. Both treatments produced elevated audibility thresholds, mainly above 1000 Hz. The effects of each treatment type on loudness judgments were evaluated to test the following predictions: (1) The EPs would enhance the magnitude of perceived loudness and the resulting loudness growth functions would become steeper as a consequence of chronic sound attenuation (consistent with enhanced system gain in response to diminished peripheral sound input); whereas, (2) the NGs would reduce the magnitude of perceived loudness and the resulting loudness growth functions would become shallower (consistent with diminished system gain in response to the elevated background input). Results after 4 weeks of each treatment were consistent with the above predictions, providing support for a plastic, chronic auditory gain process, and the use of sound therapy (i.e., NGs) in TRT.

Relation Between Neural Response Telemetry Thresholds, T- and C-Levels, and Loudness Judgments in 12 Adult Nucleus 24 Cochlear Implant Recipients

The primary purpose of this study was to determine if the contour of visual (vNRT) or predicted (tNRT) neural response telemetry (NRT) thresholds across electrodes could predict the contour of behaviorally programmed T-levels (minimum stimulation) and/or C-levels (maximum stimulation) across electrodes for well-fit MAPs. The secondary purpose was to determine the relation between NRT thresholds and loudness judgments obtained at the subject's MAP rate (250, 900, 1200, or 1800 pulses per second [pps]) and the NRT stimulus rate (80 pps). Twelve adult Nucleus 24 cochlear implant recipients participated in the study. The T- and C-levels from a preferred MAP, which had been worn for a minimum of 3 mo, were used in this study. Electrically evoked compound action potentials were measured on 11 active electrodes with NRT software (v3.0). Ascending loudness judgments from first hearing to maximum acceptable loudness were completed on these electrodes with the subject's preferred MAP rate stimulus, using the R126 (v.2.0) software and with an 80 pps rate stimulus, using the NRT software (v3.0). All measures were repeated approximately 1 mo later to determine their reliability. The reliability of the behavioral and objective measures was very high from the first to the second half of the study. The mean tNRT thresholds had a lower reliability (r = 0.73) than vNRT thresholds (r = 0.91). The loudness judgment dynamic range was notably different between rates. The NRT rate (80 pps) stimulus resulted in the narrowest dynamic range followed by increasingly wider dynamic range as the MAP rate increased. The NRT thresholds had a stronger correlation with loudness judgments made with the NRT rate stimulus than with the MAP rate stimulus. The group mean NRT thresholds were significantly correlated with C-levels (vNRT r = 0.69) (tNRT r = 0.66) but not T-levels. The relation between NRT thresholds and T- and C-levels varied for different MAP rates, with the NRT thresholds being closest to the C-levels for the 250 pps MAP rate. Each subject's vNRT thresholds and MAP levels were examined by fitting a third-order polynomial to the data. This analysis revealed significant variability demonstrating that no one fit predicts T- and C-levels well for all subjects. The results of this study provide important insight into the relation between NRT thresholds and loudness judgments for different stimulation rates and T- and C-levels at various MAP rates. The loudness judgment dynamic range and MAP dynamic range (T- and C-levels) varied notably for different stimulation rates. As a result, the relation of NRT thresholds to these measures also varied with stimulation rate. Overall, the mean vNRT thresholds fell higher in the loudness judgment dynamic range than the tNRT thresholds. Mean NRT thresholds fell between the judgments of medium soft and maximum acceptable loudness for all stimulation rates. Mean vNRT thresholds fell above C-levels, whereas almost half of tNRT thresholds fell just below C-levels. However, the relation between NRT thresholds and C-levels varied substantially for different MAP stimulation levels. In addition, there is substantial individual variability in the relation between NRT thresholds and MAP levels that is not reflected in the group data. The prediction of the contour of T- and C-levels from the contour of NRT thresholds across electrodes would not be appropriate for half of the subjects. Therefore, great care should be taken when applying a fitting rule that incorporates NRT thresholds without considering these individual differences. For adults who can provide appropriate loudness judgments and threshold responses it appears to be most efficient to primarily use behavioral measures to create MAPs.

Contributions of individual components to the overall loudness of a multitone complex

The contributions of individual components to the overall loudness of a multitone complex were examined in a two-interval, loudness judgment task. Stimuli were five-tone complexes centered on 1000 Hz, with six different logarithmic frequency spacings, corresponding to bandwidths from 46 to 2119 Hz. Stimuli were presented for 300 ms (10 ms rise/fall). The overall level of the standard complex was fixed at 60 dB SPL (53 dB/component). Levels of the individual components of the comparison complex were selected at random from a rectangular distribution with a range of 20 dB. Perceptual weights were computed by calculating the point-biserial correlation between the difference in the level of each component across the two intervals and the subject's response. When all components fell within the same critical band, weights varied little across components. In contrast, the range of weights increased with increasing frequency separation, with more weight given to the lowest and highest frequency components. A relation between component weight and masked threshold was observed for all but the widest spacing condition. Perceptual weights and masked thresholds were largely in agreement with the loudness model [Moore et al., J. Audio. Eng. Soc. 45, 224-237 (1997)], except at the widest bandwidth.

Use of perceptual weights to test a model of loudness summation

We recently examined the contribution of individual components of a multitone complex to judgments of overall loudness by computing the perceptual weight listeners assign to each component in a loudness-matching task [Leibold et al., J. Acoust. Soc. Am. 117, 2597 (2005)]. Stimuli were five-tone complexes centered on 1000 Hz, with six different logarithmic frequency spacings, ranging from 1.012 to 1.586. When all components fell within the same critical band, weights varied little across components. In contrast, the range of weights increased with increasing frequency separation, with greater weight given to the lowest and highest frequency components. Perceptual weights were largely in agreement with the Moore et al. loudness model [J. Audio Eng. Soc. 45, 224–237 (1997)], except at the widest bandwidth. In the current study we further examined predictions of the loudness model, focusing on the widest frequency-spacing condition. Masked thresholds and jnds for intensity discrimination were measured for each component and were compared to weights. The model predicts more interaction in the widely spaced conditions than simple critical band models, but underestimates the true interactions in conditions where components are widely spaced. Central factors appear to influence loudness, masked thresholds, and intensity discrimination in these conditions. [Work supported by NIH/NIDCD.]