Publications by authors named "Leonard Varghese"

Objective: The aim of this study was to explore the potential for bimodal auditory and noninvasive electrical stimulation at the ears to alleviate tonal, somatic tinnitus that was investigated in a small preliminary trial (11 participants).

Design: Auditory stimulation took the form of short "notched noise" bursts customized to each participant's tinnitus percept. Simultaneous pulsed electrical stimulation, intended to facilitate neuroplasticity, was delivered via hydrogel electrodes placed in opposite ears.

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Listeners performed two different tasks in which they remembered short sequences comprising either complex tones (generally heard as one melody) or everyday sounds (generally heard as separate objects). In one, listeners judged whether a probe item had been present in the preceding sequence. In the other, they judged whether a second sequence of the same items was identical in order to the preceding sequence.

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Article Synopsis
  • The ability to tell the difference between two sounds gets worse as the time between the sounds gets longer.
  • Researchers think this might happen because our minds "forget" the sounds over time, which increases confusion.
  • A study with musicians showed that while people generally had more confusion as time between sounds increased, they also started guessing more at very long time intervals, indicating that both forgetting and guessing are involved in how we hear sounds.
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Article Synopsis
  • Perceptual anchors are things we remember about sounds that help us recognize them later, and they come from our long-term memory.
  • In an experiment, ten amateur musicians listened to different tones to see how well they could tell the difference between them.
  • The study found that when the first tone stayed the same, the musicians did better at telling differences between tones because they used their memory more effectively, but had a harder time when the tones changed a lot.
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Cross-modal interactions of auditory and visual temporal modulation were examined in a game-like experimental framework. Participants observed an audiovisual stimulus (an animated, sound-emitting fish) whose sound intensity and/or visual size oscillated sinusoidally at either 6 or 7 Hz. Participants made speeded judgments about the modulation rate in either the auditory or visual modality while doing their best to ignore information from the other modality.

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Auditory brainstem responses (ABRs) and their steady-state counterpart (subcortical steady-state responses, SSSRs) are generally thought to be insensitive to cognitive demands. However, a handful of studies report that SSSRs are modulated depending on the subject׳s focus of attention, either towards or away from an auditory stimulus. Here, we explored whether attentional focus affects the envelope-following response (EFR), which is a particular kind of SSSR, and if so, whether the effects are specific to which sound elements in a sound mixture a subject is attending (selective auditory attentional modulation), specific to attended sensory input (inter-modal attentional modulation), or insensitive to attentional focus.

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