The acoustic frequencies of fingernails on a chalkboard activate specific aversiveness pathways in the human brain
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Neuroimaging studies demonstrate that aversive sounds such as chalk screeching on a blackboard activate brain pathways involving the auditory cortex and amygdala, which process their unpleasant valence.
Perception & Psychophysics 1986, 39 (2), 77-80
## Psychoacoustics of a chilling sound
D. LYNN HALPERN, RANDOLPH BLAKE, and JAMES HILLENBRAND
Northwestern University, Evanston, Illinois
We digitally synthesized versions ofthe sound of a sharp object scraping across a slate surface
(which mimics the sound offingernails scraping across a blackboard) to determine whether spec
tral content or amplitude contour contributed to its obnoxious quality. Using magnitude estima
tion, listeners rated each synthesized sound's unpleasantness. Contrary to intuition, removal of
low, but not of high, frequencies lessened the sound's unpleasantness. Manipulations ofthe sig
nal amplitude had no significant impact on listeners' unpleasantness estimates. Evidently, low
frequency spectral factors contribute primarily to the discomfort associated with this sound.
Most people cringe when fingernails are scraped across a chalkboard; for some individuals simply imagining this aversive event evokes a wince. Rare (and perverse) is the person who smiles while sending shivers down the spines of others by scratching a hard surface. So ubiquitous is the reflexive reaction to these kinds of scraping soun
A dynamic system for the analysis of acoustic features and valence of aversive sounds in the human brain - PubMed
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## Abstract
Certain sounds, for example, the squeal of chalk on a blackboard, are perceived as highly unpleasant. Functional magnetic resonance imaging (fMRI) in humans shows responses in the amygdala and auditory cortex to aversive sounds. Dynamic causal modelling (DCM) of the interaction between auditory cortex and the amygdala revealed that evoked responses to aversive sounds are relayed to the amygdala via the auditory cortex. There is a complex interaction between the -auditory cortex and amygdala involving effective connectivity in both directions. While acoustic features modulate forward connections from auditory cortex to the amygdala, the valence modulates effective connectivity from the amygdala to the auditory cortex. The results support interaction between the auditory cortex and amygdala where stimuli are first processed to a higher (object) level in the auditory cortex before assignment of valence in the amygdala.
## Publication types
Research Support, Non-U.S. Gov't
Mapping unpleasantness of sounds to their auditory representation - PubMed
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## Abstract
Certain sounds, for example, the squeal of chalk on a blackboard, are typically perceived as highly unpleasant. This study addressed the question of what aspects of the auditory representation of such sounds are associated with judgments of unpleasantness. Participants rated the perceived unpleasantness of a large number of sounds that included "griding" and other unpleasant sounds. A multivariate partial least-squares (PLS) model was then built to relate the ratings of unpleasantness with an auditory representation derived from a model of processing in the auditory pathway. The "existence region" of unpleasantness in the auditory space of frequency-temporal modulation was determined after the PLS model had been validated by predicting the unpleasantness of novel sounds from the auditory representation. It was observed that the existence region corresponded to spectral frequencies between 2500 and 5500 Hz, and temporal modulations in the range 1-16 Hz.
## MeSH terms
Acoustic Stimulation
Adult
Animals
Auditory Cort
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