Cortical Evoked Response to Gaps in Noise: Within-Channel and Across-Channel Conditions

Abstract

Objectives-The objective of this study was to describe the cortical evoked response to silent gaps in a group of young adults with normal hearing using stimulus conditions identical to those used in psychophysical studies of gap detection. Specifically, we sought to examine the P1-N1-P2 auditory evoked response to the onsets of stimuli (markers) defining a silent gap for withinchannel (spectrally identical markers) and across-channel (spectrally different markers) conditions using four perceptually-equated gap durations. It was hypothesized that (1) P1, N1, and P2 would be present and consistent for 1st marker (before the gap) onsets; (2) for within-channel markers, P1, N1, and P2 would be present for 2nd marker (after the gap) onsets only when the gap was of a duration equal to or larger than the behaviorally measured gap detection threshold; and (3) for the across-channel conditions, P1, N1, and P2 would be present for 2nd marker onsets regardless of gap duration. This is expected due to the additional cue of frequency change following the gap.Design-Twelve young adults (mean age 26 years) with normal hearing participated. Withinchannel and across-channel gap detection thresholds were determined using an adaptive psychophysical procedure. Next, cortical auditory evoked potentials (P1-N1-P2) were recorded with a 32-channel Neuro-scan™ electroencephalogram system using within-channel and acrosschannel markers identical to those used for the psychophysical task and four perceptually weighted gap durations: (1) individual listener's gap detection threshold; (2) above gap detection threshold; (3) below gap detection threshold; and (4) a 1-ms gap identical to the gap in the standard interval of the psychophysical task. P1-N1-P2 peak latencies and amplitudes were analyzed using repeated-measures analyses of variance. A temporal-spatial principal component analysis was also conducted.Results-The latency of P2 and the amplitude of P1, N1, and P2 were significantly affected by the acoustic characteristics of the 2nd marker as well as the duration of the gap. Larger amplitudes and shorter latencies were generally found for the conditions in which the acoustic cues were most salient (e.g., across-channel markers, 1st markers, large gap durations). Interestingly, the temporal-spatial principal component analysis revealed activity elicited by gap durations equal to gap detection threshold in the latency regions of 167 and 183 ms for temporal-parietal and rightfrontal spatial locations.Address for correspondence: Jennifer Lister, Department of Communication Sciences and Disorders, University of South Florida, 4202 E. Fowler Ave. PCD 1017, Tampa, FL 33620. jlister@cas.usf.edu.. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptConclusions-The cortical response to a silent gap is unique to specific marker characteristics and gap durations among young adults with normal hearing. Specifically, when the onset of the 2nd marker is perceptually salient, the amplitude of the P1-N1-P2 re...

Hearing an Illusory Vowel in Noise: Suppression of Auditory Cortical Activity

“…The latter enhancement was further significantly stronger than the former (t 13 ϭ 2.9, p Ͻ 0.02). The timing of these enhancements was consistent with that reported by EEG studies on gap detection in noise (Michalewski et al, 2005;Pratt et al, 2005;Lister et al, 2007), tones (Heinrich et al, 2004), or noiseinterrupted tones (Riecke et al, 2009b). They further matched previously observed increases in 4 Hz power to sound onsets and offsets (Makeig, 1993;Riecke et al, 2009b).…”

Auditory discrimination: The relationship between psychophysical and electrophysiological measures

“…In terms of the effect of gap duration on ACC latency, the findings have not been consistent. Whereas some researchers found a significant effect (Pratt et al, 2005; Lister et al, 2007), other researchers reported no effect at all (Michalewski et al, 2005). In addition, the effect of intensity change on ACC latency is still unknown.…”

“…Jones and colleagues (Jones et al, 1998; Jones and Perez, 2001, 2002) reported that the ACC response could also be recorded in response to changes in pitch and/or timbre of synthesized music. In addition, several studies have shown that the ACC response can be recorded using ongoing stimuli that contain silent gaps of various durations (Michalewski et al, 2005; Pratt et al, 2005, 2007; Lister et al, 2007; Atcherson et al, 2009). Results of these studies showed that the ACC amplitude increased with increasing magnitude of acoustic changes in intensity (Martin and Boothroyd, 2000; Harris et al, 2007; Dimitrijevic et al, 2009, 2011), spectrum (Harris et al, 2008; Dimitrijevic et al, 2009, 2011), and gap duration (Michalewski et al, 2005).…”

Comparison of Regularity Detection between Individuals with and without Speech-in-Noise Problems using Electrophysiological Methods

“…For example, a repeating sound at a random frequency and a repeating three-sound pattern appearing after random frequency sounds have been found to be evoking magnetic 100 (M100) responses [electroencephalography (EEG) N1 response] in the root mean square amplitude waveform of magnetoencephalography recordings [5,6] . In fact, cortical implications of auditory processes, ranging from the detection of sound onset to the detection of frequency changes as well as the detection of embedded gaps in continuous noise, are reflected on N1 responses, the magnetic counterpart of which is the M100 response [7][8][9][10][11][12] .…”