Auditory Intensity Discrimination Research Articles

Opening a window into the riddle of misophonia, sensory over-responsiveness, and pain.

IntroductionMisophonia and sensory over-responsiveness (SOR) share physiological and psychological symptoms. While individuals with SOR demonstrate pain perception alterations, these were not explored in misophonia.MethodsThis exploratory study comprised thirty healthy adults with (n = 15; based on the Misophonia Questionnaire) and without misophonia. The Sensory Responsiveness Questionnaire (SRQ) was used for evaluating sensory responsiveness. In addition, psychophysical tests were applied for quantification of: (i) stimulus-response function of painful stimuli, (ii) the individual perceived pain intensity, (iii) pain modulation efficiency, (iv) auditory intensity discrimination capability, and (v) painful and unpleasantness responses to six ecological daily sounds using the Battery of Aversiveness to Sounds (BAS).ResultsIndividuals with misophonia reported higher scores in the SRQ-Aversive (p = 0.022) and SRQ-Hedonic (p = 0.029) scales as well as in auditory (p = 0.042) and smell (p = 0.006) sub-scales, indicating higher sensory responsiveness. Yet they were not identified with the SOR type of sensory modulation dysfunction. Groups did not differ in the pain psychophysical tests, and in auditory discrimination test scores (p > 0.05). However, in the misophonia group the BAS evoked higher pain intensity (p = 0.046) and unpleasantness (p <0.001) ratings in the apple biting sound, and higher unpleasantness rating in the scraping a dish sound (p = 0.007), compared to the comparison group.ConclusionFindings indicate increased sensory responsiveness in individuals with misophonia, yet not defined as SOR. Thus, this suggests that misophonia and SOR are two distinct conditions, differing in their behavioral responses to painful and non-painful stimuli.

RETRACTED ARTICLE: Neural auditory intensity discrimination during naturalistic listening: a brain decoding study.

Neural discrimination of auditory intensity is one of the fundamental questions in human auditory perception. Human neuroimaging studies have demonstrated specific neural activations during intensity discrimination tasks. The detailed functional anatomy, however, remains elusive. Most of the existing studies examined the entire auditory cortex as a whole, neglecting the potential functional differentiation within the auditory cortex. Moreover, these previous results based on controlled auditory stimuli might not necessarily extend to the neural mechanism of natural auditory processing. In this study, we propose a novel brain decoding method to examine neural encoding of intensity discrimination during naturalistic auditory experience. Here, we used publically available dataset (http://studyforrest.org) in which high resolution functional magnetic resonance imaging (fMRI) was acquired when the participants freely listened to the audio-version of the movie “Forrest Gump”. We found the sensitivity and accuracy of intensity discrimination in the auditory cortex critically depend on the divergences in intensity levels, yielding a sigmoidal relationship. Furthermore, anatomical subdivisions of auditory cortex revealed great functional diversity and lateralization in intensity discrimination. While bilateral activations were observed in primary auditory cortex, enhanced left-lateralization effects were shown in inferior frontal gyrus, anterior middle temporal gyrus and temporal-occipital junction. Our findings underscore the value of naturalistic paradigms in mapping auditory processing in the brain: naturalistic paradigm contains enriched and complex natural sounds, which not only improve the ecological validity but also alleviate the discrepancies caused by the differences in stimulus types and task designs in previous studies. The multidisciplinary methodology we developed here provides an analytical framework for studying neural encoding of complex auditory stimuli.

Auditory intensity processing: Effect of MRI background noise

Studies on active auditory intensity discrimination in humans showed equivocal results regarding the lateralization of processing. Whereas experiments with a moderate background found evidence for right lateralized processing of intensity, functional magnetic resonance imaging (fMRI) studies with background scanner noise suggest more left lateralized processing. With the present fMRI study, we compared the task dependent lateralization of intensity processing between a conventional continuous echo planar imaging (EPI) sequence with a loud background scanner noise and a fast low-angle shot (FLASH) sequence with a soft background scanner noise. To determine the lateralization of the processing, we employed the contralateral noise procedure. Linearly frequency modulated (FM) tones were presented monaurally with and without contralateral noise. During both the EPI and the FLASH measurement, the left auditory cortex was more strongly involved than the right auditory cortex while participants categorized the intensity of FM tones. This was shown by a strong effect of the additional contralateral noise on the activity in the left auditory cortex. This means a massive reduction in background scanner noise still leads to a significant left lateralized effect. This suggests that the reversed lateralization in fMRI studies with loud background noise in contrast to studies with softer background cannot be fully explained by the MRI background noise.

Audiovisual congruency and incongruency effects on auditory intensity discrimination

This study used a S1–S2 matching paradigm to investigate the influences of visual (size) change on auditory intensity discrimination. Behavioral results showed that subjects made more errors and spent more time to discriminate change in auditory intensity when it was accompanied by an incongruent visual change, while the performance for congruent audiovisual stimuli was better especially if there is a change in auditory stimuli. Event-related potential difference waves revealed that audiovisual interactions for multimodal mismatched information processing activated the right frontal and left centro-parietal cortices around 300–400ms post S1-onset.

Why do forward maskers affect auditory intensity discrimination? Evidence from "molecular psychophysics".

Nonsimultaneous maskers can strongly impair performance in an auditory intensity discrimination task. Using methods of molecular psychophysics, we quantified the extent to which (1) a masker-induced impairment of the representation of target intensity (i.e., increase in internal noise) and (2) a systematic influence of the masker intensities on the decision variable contribute to these effects. In a two-interval intensity discrimination procedure, targets were presented in quiet, and combined with forward maskers. The lateralization of the maskers relative to the targets was varied via the interaural time difference. Intensity difference limens (DLs) were strongly elevated under forward masking but less with contralateral than with ipsilateral maskers. For most listeners and conditions, perceptual weights measuring the relation between the target and masker levels and the response in the intensity discrimination task were positive and significant. Higher perceptual weights assigned to the maskers corresponded to stronger elevations of the intensity DL. The maskers caused only a weak increase in internal noise, unrelated to target level and masker lateralization. The results indicate that the effects of forward masking on intensity discrimination are determined by an inclusion of the masker intensities in the decision variable, compatible with the hypothesis that the impairment in performance is to a large part caused by difficulties in directing selective attention to the targets. The effects of masker lateralization are evidence for top-down influences, and the observed positive signs of the masker weights suggest that the relevant mechanisms are located at higher processing stages rather than in the auditory periphery.

Formerly known as inhibitory: effects of 1‐Hz rTMS on auditory cortex are state‐dependent

The major repetitive transcranial magnetic stimulation (rTMS) paradigm applied to the treatment of tinnitus has been the 1-Hz variant due to its alleged inhibitory effects. Clinical effects have, however, been hampered by great interindividual variability as well as the fact that TMS includes no explicit mechanism to modulate excitability in circumscribed regions of tonotopically organised auditory fields. Following studies showing that the effect of TMS depends on the activational state preceding the stimulation, participants were exposed to 10 min of either notch- or bandpass-filtered noise prior to 1-Hz rTMS applied to the left auditory cortex. A control group was additionally assessed using bandpass noise - albeit with subsequent sham stimulation - to assess whether effects were due to the differential sounds alone or to a genuine interaction between sound and rTMS. Electroencephalogram was recorded from 128 electrodes before and after the experimental treatment while participants performed an auditory intensity discrimination task. While state-dependency effects from the behavioural data are not conclusive, several condition × (sound) frequency effects (some specific to the stimulated side) could be observed. Importantly, many of these could not be explained by the use of rTMS or the filtered noise alone. The resulting patterns are, however, complex and temporally variable, which currently prohibits recommendations on how to design a clinically effective approach to treat tinnitus. Nevertheless, our study gives the first evidence that state-dependency principles can induce sound frequency-specific effects in the auditory cortex, providing a crucial proof-of-principle upon which future studies can build.

Spectral profile cues in comodulation masking release

Previous work on spectral shape discrimination has shown that detection of a level increment in one tone of a tonal complex is dependent on spectral position, with thresholds forming a "bowl" pattern for components spanning 200 to 5000 Hz [Green, D. M., (1988). Profile Analysis: Auditory Intensity Discrimination (Oxford University Press, New York)]. The current study examined whether a similar bowl occurs for comodulation masking release, a paradigm in which dynamic spectral cues could be used to detect an added signal. Maskers were logarithmically spaced 15-Hz-wide bands of noise. The signal was a tone or a copy of the on-signal masker band. When the masker was composed of one or more random bands, thresholds were relatively consistent across frequency. When the masker was a set of comodulated bands, thresholds for both signal types formed a bowl, but the minimum threshold occurred at a higher signal frequency for the tonal than for the narrowband noise signal. Results for additional conditions indicate that spectral effects depend on both absolute frequency and relative frequency of the signal within the masker. Data collected with flanking maskers presented contralateral to the signal and on-signal masker indicate that peripheral effects may play a role in threshold elevation at high signal frequencies with narrowband noise signals.

Auditory intensity discrimination as a function of level-rove and tone duration in normal-hearing and impaired subjects: The “mid-level hump” revisited

The just-noticeable difference (ΔI) in the intensity (I) of sound is typically reported to be a constant or a slightly decreasing ratio of the baseline intensity (known as Weber’s law, and the “near-miss to Weber’s law”, respectively). However, in the relatively few studies on the intensity discrimination of very brief sounds, ΔI/I is usually found to be non-monotonic, with poorest discrimination in the middle of the auditory dynamic range. Here, it is demonstrated that this “severe departure from Weber’s law” or “mid-level hump” is not merely a phenomenon of short-duration sounds. In normal-hearing subjects ( n = 8), the near-miss to Weber’s law that is observed with the discrimination of 300 ms-long, 4 kHz tones, gives way to a significant mid-level hump if tone intensities are not fixed over a great many trials (as is standard practice) but are instead randomly roved, trial-to-trial, over a wide intensity range. This was not the case in subjects with mild to moderate hearing impairment ( n = 4). Furthermore, in the discrimination of widely-roved, 4 ms-long, 4 kHz tone bursts, the performance of normal-hearing subjects did not significantly worsen at mid-levels compared to the unroved condition, unlike what was found with the 300 ms-long tones. It is suggested that mid-level humps could simply be the product of the well-known mid-level compressive nonlinearity in cochlear mechanics. We further suggest that the hump is eliminated, and the near-miss to Weber’s law is produced, by a more central mechanism such as the recently reported “adaptation to sound-level statistics”, which is bypassed during wide-range roving and possibly when sound durations are brief.

Is auditory intensity discrimination a comparison of entropy changes

In JASA (97, 1995), Wong &amp; Norwich presented a Weber-fraction equation derived from McConville, Norwich, &amp; Abel (Int J Biomed Comput 27, 1991). The latter modeled two-alternative forced-choice discrimination between stimuli of identical spectra and identical durations “t” but differing intensities I and I+ΔI. Discrimination depended on ΔH(I,t), the change in the information-theoretic entropy over t and ΔI. ΔH(I,t), assumed constant over intensities, emerged as one of five unknowns in a Weber-fraction equation, (ΔI)/I=f(t0,tW,n,β,ΔH(I,t)). McConville et al. presumed values for n and tW. Using (ΔI)/I≈ΔH(I,t)/(IΔt[∂2H/∂I∂t]) and setting Δt=t, f(t0,tW,n,β,ΔH(I,t)) was approximated as g(n,(β/t),ΔH(I,t)) =ΔH(I,t)/(It[∂2H/∂I∂t]), which was then curvefitted to one listener's Weber fractions. The obtained ΔH(I,t) alone was substituted back into f(t0,tW,n,β,ΔH(I,t)), which was then substantiated by curvefitting to the data to reveal the remaining unknowns, t0 and β. McConville et al. had to curvefit, because they model only a single, unspecified forced-choice trial, making ΔI any intensity change; and none of the unknowns could legitimately be presumed. The curvefitting was flawed: the assumption ΔH(I,t)=constant affirms Fechner's postulate; and ∂2H/∂I∂t&amp;lt;0, giving a negative Weber fraction. McConville et al. fail to explain auditory intensity discrimination as a comparison of entropy changes, casting doubt on Wong &amp; Norwich (1995).

Testing a new theory of Fechnerian scaling: The case of auditory intensity discrimination

Recently, Dzhafarov and Colonius [Psych. Bull. Rev. 6, 239–268 (1999)] proposed a theory that refines Fechner’s ideas of deriving the perceptual distance between stimuli from discriminability measures in the unidimensional case, and generalizes it to multidimensional stimulus domains. In this theory, the existence of a Fechnerian metric is based on testable assumptions about the shape of the psychometric functions. Thus, ‘‘same–different’’ psychometric functions: (1) have to attain a single minimum at some point; (2) must be locally symmetric around their minima; and (3) must show the same degree of cuspidness, or flatness, along the stimulus continuum. In the present investigation, these assumptions were evaluated experimentally employing acoustical stimuli differing along one stimulus dimension, intensity. In a ‘‘same–different’’ paradigm, using the method of constant stimuli, seven 1000-Hz tones deviating from 0 to 2.1 dB with respect to a standard were presented diotically to five observers. For every participant, psychometric functions were assessed at five hearing levels ranging from 40- to 80-dB HL. The outcome of the ‘‘same–different’’ experiments generally supports the assumptions of the theory. Therefore, data such as these are, in principle, suitable for deriving a global loudness scale from local discriminability measures.

Relationship between auditory intensity discrimination in noise and olivocochlear efferent system activity in humans.

Relationship between auditory intensity discrimination in noise and olivocochlear efferent system activity in humans.

Involuntary Listening AIDS Hearing

In two experiments, I simultaneously measured response time, accuracy, and response bias in an auditory intensity discrimination task to look for evidence of stimulus-driven attention orienting in auditory frequency space. The results demonstrated that a cue tone caused an apparently involuntary orienting of attention to the cue's frequency region, allowing faster and more accurate processing of a subsequent target tone when it occurred at the same frequency as the cue than when it occurred at a different frequency. Relationships between response time, accuracy, and bias measures also allowed masking and other effects to be separated from attention-orienting effects in these experiments.

Relationship between auditory intensity discrimination in noise and olivocochlear efferent system activity in humans.

Recent physiological data in animals suggest a role of the medial olivocochlear system (MOCS) in auditory intensity discrimination in noise. In this study, the existence of statistical relationships between intensity difference limens (IDLs) and MOCS functioning was tested in humans. IDLs were measured in conditions of quiet and of ipsilateral, contralateral, and dichotic noise. MOCS functioning was assessed through the contralateral evoked otoacoustic emission (EOAE) amplitude attenuation effect. A first finding was that IDLs measured in the presence of ipsilateral noise were reduced when contralateral noise was added. Furthermore, the observed shift in IDL appeared to be significantly correlated to the contralateral EOAE amplitude attenuation effect. These results support the hypothesis that MOCS functioning plays a role in intensity discrimination in dichotic noise in humans.

Stimulus fluctuations in auditory intensity discrimination.

A basic prediction of Green’s [J. Acoust. Soc. Am. 32, 121–131 (1960)] classical energy‐detection theory for Gaussian signals is a variance measure of stimulus fluctuation that decreases monotonically with the signal’s duration‐bandwidth product (TW). Experiments on intensity discrimination of narrow‐band Gaussian noise provide the most direct support of this prediction for TW<∼16, but indicate a need for another source of fluctuation for larger TW which could reflect internal noise [deBoer, J. Acoust. Soc. Am. 40, 552–560 (1966)]. An alternative solution is proposed based on detection of the largest waveform peak within the analysis window (≥T). Investigation of this detector for narrow‐band Gaussian noise shows that the variance (in dB) of the peak fluctuations is the sum of the variances of the classical energy fluctuation and of a waveform fluctuation due to random phases. For TW<20 the energy fluctuation dominates, while the waveform fluctuation dominates for larger TW. Predictions of the classical energy detection model with an internal noise of 1 dB are essentially indistinguishable from the peak detector model for intensity discrimination thresholds of narrow‐band Gaussian noise; however, peak detection explains a wider range of experiments [Goldstein, J. Acoust. Soc. Am. 98, 2907(A) (1995)].

A composite randomization procedure for measuring spectral shape discrimination.

In studies of auditory profile analysis [D. M. Green, Profile Analysis: Auditory Intensity Discrimination (Oxford U. P., New York, 1988)], the sounds are presented at random levels to discourage the listener from basing the discrimination on a difference in absolute level rather than on a difference in the shape of the spectrum. A difference in absolute level, however, can still provide an effective discrimination cue if the difference is comparable to the range of randomization. Using enormous ranges of random levels is not desirable, because it is distracting to normal listeners and may exceed the dynamic range of hearing for listeners with hearing loss. This article describes a new experimental procedure which permits the experimenter to greatly reduce the range of level randomization in roving-level tasks.

Application of the entropy theory of perception to auditory intensity discrimination

The entropy theory of perception has been developed from principles of information theory and predicts both psychophysical data and firing rates of sensory receptors or primary afferents. It has demonstrate how mathematical relationships subsist among many previously unrelated phenomena, such as adaptation processes, reaction times and subjective magnitudes and can be applied to most modalities of perception The current study demonstrates how the theory can be applied to intensity discrimination of auditory pure tones. A psychophysical experiment of intensity discrimination was carried out under computer control in three practiced normal hearing listeners. Three different derivations for the entropic description of intensity discrimination were applied to the data and analyzed in terms of computer generated best-fitti parameters. The physiological meaning of these parameters is discussed.

Detection of changes in spectral shape: Uniform vs. non-uniform background spectra

In most of the previous studies [(1987) Profile Analysis: Auditory Intensity Discrimination, Oxford Univ. Press] concerning the detection of a change in spectral shape, or ‘profile analysis’, the listener's task was to detect an increment to a single component pf an otherwise equal-amplitude, multi-component background. We wished to determine whether listeners would exhibit sensitivity to changes in spectral shape if the spectrum of the background were not flat. The results of two experiments, like those of Green and Kidd [(1983) J. Acoust. Soc. Am. 73,1260–1265], indicate that the spectrum of the background can deviate rather substantially from ‘flat’ before detection of the signal becomes more difficult. In a third experiment, we investigated how the function relating the threshold of the signal to the frequency of the signal would vary as the number of components in a flat multi-component background is altered. Our results indicate that as the number of components which compose the background is reduced from 21 to 3, thresholds for increments to the middle region of the spectrum are elevated rather considerably.

Auditory intensity discrimination in the chinchilla.

A positive reinforcement conditioning procedure was used to train chinchillas to respond to intensity differences between successively occurring tone bursts. Intensity difference limens were measured at 0.5, 1, 4, and 8 kHz at five intensities ranging from 10- to 55-dB sensation level. The intensity difference limen decreased from approximately 8 dB near threshold to approximately 3.5 dB at the highest level. The intensity difference limens for the chinchilla were considerably larger than those for humans as well as several other mammals; however, the results were similar to those obtained for the parakeet. The present results from intensity discrimination appeared to be related to previous data for the discrimination of amplitude modulated noise.

Intensity discrimination and loudness for tones in notched noise.

Fechner proposed that equally often noticed differences are subjectively equal. Parker and Schneider (1980) showed that a power-function representation for loudness was consistent with Fechner’s proposal for auditory intensity discrimination when 1-kHz tones were presented in a quiet background. In the present experiment, (1) intensity-increment thresholds were determined for 1-kHz tones in notched noise, and (2) the intensities of 1-kHz tones in quiet which produced the same loudnesses as the tones in notched noise were obtained from the same subjects. Intensityincrement thresholds in notched noise could not be accounted for by either the loudness level of the tones in notched noise or by the Parker and Schneider model. A new model is developed in which the effects of notched noise on discrimination performance are related to the effects of notched noise on loudness.

Auditory intensity discrimination at high frequencies in the presence of noise.

Over a wide range of intensities, subjects were able to detect small differences in the intensity of a high-frequency band of noise that was presented with a relatively intense, complementary band-reject noise. This indicates that neither of two possible mechanisms for peripheral intensity coding, those based on timing and on spread of excitation, is necessary for the large dynamic range of human hearing. It is shown that the information available in the firing rate of a small number of nerve fibers can account for these data.