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

A psychoacoustical study to investigate the perceived unpleasantness of infrasound combined with audio-frequency sound

At many immission sites of infrasound (frequency f < 20 Hz), humans are exposed to a mixture of infrasound and sound in the common audio-frequency range (audio sound, 20 Hz < f < 20 kHz). Therefore, the purpose of this study was to examine the auditory perception of infrasound and audio sound not only in isolation but also in combination. This laboratory study aims to investigate the perceived unpleasantness of infrasound (sinusoid at 12 Hz) and audio sound (sinusoid at 1000 Hz, pink-noise 250–4000 Hz), presented alone or in combination with each other. A pairwise comparison task and a rating task using a numerical scale were conducted with 19 normal hearing listeners. In addition, individual detection thresholds were determined for the infrasound stimulus. Combinations of infrasound and audio sound were rated as equally or more unpleasant than either sound presented alone. Inter-individual differences in unpleasantness ratings using the numerical scale were particularly high for stimuli containing infrasound. This can only in part be related to the large variability in infrasound thresholds. These findings suggest that simultaneous exposure to infrasound and audio sound can increase the perceived unpleasantness when both are presented at a sufficient level above the detection threshold

A psychoacoustical study to investigate the perceived unpleasantness of infrasound combined with audio-frequency sound

At many immission sites of infrasound (frequency f < 20 Hz), humans are exposed to a mixture of infrasound and sound in the common audio-frequency range (audio sound, 20 Hz < f < 20 kHz). Therefore, the purpose of this study was to examine the auditory perception of infrasound and audio sound not only in isolation but also in combination. This laboratory study aims to investigate the perceived unpleasantness of infrasound (sinusoid at 12 Hz) and audio sound (sinusoid at 1000 Hz, pink-noise 250–4000 Hz), presented alone or in combination with each other. A pairwise comparison task and a rating task using a numerical scale were conducted with 19 normal hearing listeners. In addition, individual detection thresholds were determined for the infrasound stimulus. Combinations of infrasound and audio sound were rated as equally or more unpleasant than either sound presented alone. Inter-individual differences in unpleasantness ratings using the numerical scale were particularly high for stimuli containing infrasound. This can only in part be related to the large variability in infrasound thresholds. These findings suggest that simultaneous exposure to infrasound and audio sound can increase the perceived unpleasantness when both are presented at a sufficient level above the detection threshold

The representation of peripheral neural activity in the middlelatency evoked field of primary auditory cortex in humans. Hearing research 174

Abstract Short sweeps with increasing instantaneous frequency (up-chirps) designed to compensate for the propagation delay along the human cochlea enhance the magnitude of wave V of the auditory brainstem responses, while time reversed sweeps (down-chirps) reduce the magnitude of wave V [Dau, T., Wegner, O., Mellert, V., Kollmeier, B., J. Acoust. Soc. Am. 10

Data from: Auditory functional magnetic resonance imaging in dogs – normalization and group analysis and the processing of pitch in the canine auditory pathways

Background: Functional magnetic resonance imaging (fMRI) is an advanced and frequently used technique for studying brain functions in humans and increasingly so in animals. A key element of analyzing fMRI data is group analysis, for which valid spatial normalization is a prerequisite. In the current study we applied normalization and group analysis to a dataset from an auditory functional MRI experiment in anesthetized beagles. The stimulation paradigm used in the experiment was composed of simple Gaussian noise and regular interval sounds (RIS), which included a periodicity pitch as an additional sound feature. The results from the performed group analysis were compared with those from single animal analysis. In addition to this, the data were examined for brain regions showing an increased activation associated with the perception of pitch. Results: With the group analysis, significant activations matching the position of the right superior olivary nucleus, lateral lemniscus and internal capsule were identified, which could not be detected in the single animal analysis. In addition, a large cluster of activated voxels in the auditory cortex was found. The contrast of the RIS condition (including pitch) with Gaussian noise (no pitch) showed a significant effect in a region matching the location of the left medial geniculate nucleus. Conclusion: By using group analysis additional activated areas along the canine auditory pathways could be identified in comparison to single animal analysis. It was possible to demonstrate a pitch-specific effect, indicating that group analysis is a suitable method for improving the results of auditory fMRI studies in dogs and extending our knowledge of canine neuroanatomy

Deductive development and validation of a measure to assess sensitivity to infra- low and ultra- high frequency sound

Auditory research as well as complaints about environmental noise indicate that there might exist a small but significant percentage of individuals within the population who are sensitive towards infra- and low-frequency or ultra- and high-frequency sounds (ILF/ UHF). This paper reports on the development, factorization and construct validation of a questionnaire to measure frequency sensitivity at frequencies outside the common hearing range. Principal component and exploratory factor analyses, based on a sample of N = 267 Europeans, mainly from the UK, Slovenia, and Germany, suggested that ILF vs. UHF sensitivity constitute different factors that include sensory perception, stress responsivity, and behavioral avoidance of these extreme frequencies. A third factor emerged, comprising beliefs of dangerousness associated with ILF and/or UHF. The factors explained 72% of the total variance. The factor-solution was robust and replicated separately for the English (n = 98) and the German (n = 169) versions of the questionnaire (Slovenians filled out the English version as did participants from the UK). The resulting scales had acceptable to excellent reliability. ILF and UHF sensitivity were only moderately related to established measures of noise sensitivity in the normal hearing range, suggesting that our scales likely capture a sufficiently distinct type of sensitivity. Correlations with psychiatric and somatic symptoms were small to moderate. Only ILF sensitivity correlated with neuroticism and daytime sleepiness (moderate effect), while both ILF and UHF sensitivity were significantly related to agreeableness (comprising all small effects). In sum, we conclude that our ILF and UHF sensitivity scales provide a solid starting point for conducting further research on the prediction of inter-individually divergent effects (e.g. health outcomes, annoyance ratings) of ILF and UHF sound, as moderated by sensitivity. The questionnaire consortium recommends using the new scales in combination with established measures of sensitivity in the normal hearing range

auditory_fmri_dog.zip.003

This is the third part of the zip file containing all data necessary for the functional analysis as presented in the manuscript