Middle-Latency and 40-Hz Auditory Evoked Responses in Normal-Hearing Subjects

1986 ◽  
Vol 29 (1) ◽  
pp. 20-28 ◽  
Author(s):  
Paul Kileny ◽  
Susan L. Shea
Keyword(s):  
Normal Hearing ◽  
Evoked Responses ◽  
Auditory Evoked Responses ◽  
Middle Latency ◽  
40 Hz

Electrophysiologic Assessment of Low-Frequency Hearing: Sedation Effects

1989 ◽  
Vol 101 (4) ◽  
pp. 434-441 ◽  
Author(s):  
Constantine W. Palaskas ◽  
Michael J. Wilson ◽  
Robert A. Dobie
Keyword(s):  
Cross Correlation ◽  
Low Frequency ◽  
Correlation Method ◽  
Normal Hearing ◽  
Hearing Level ◽  
Evoked Responses ◽  
Middle Latency Response ◽  
Latency Response ◽  
Middle Latency ◽  
40 Hz

Sixteen normal-hearing adults were tested in both awake and sedated states for several evoked responses to low-frequency stimuli. Responses obtained by cross-correlation function, middle latency responses, and the 40-Hz response proved most sensitive; all had mean thresholds of less than 20 dB normal hearing level for the awake-alert state, but 40-Hz and middle latency response mean thesholds were shifted about 10 dB under sedation. The cross-correlation method seems to offer promise for pediatric auditory assessment.

Auditory Evoked Responses in Normal Hearing Adults and Children Before and During Sedation

1969 ◽  
Vol 12 (2) ◽  
pp. 394-401 ◽  
Author(s):  
Paul Skinner ◽  
Frank Antinoro
Keyword(s):  
Preschool Children ◽  
Evoked Potential ◽  
Normal Hearing ◽  
Auditory Stimuli ◽  
Evoked Responses ◽  
Auditory Evoked Responses ◽  
Adults And Children ◽  
Awake Condition ◽  
Wave Complex ◽  
Prominent Peak

Averaged evoked responses (AER) to auditory stimuli presented to young children and adults were compared between awake and induced sleep conditions. Eight adults and twenty preschool children with normal hearing were tested before and during sedation at two suprathreshold levels with tone pips centered at 510, 1020, and 2040 Hz. Responses obtained during sedation assumed a distinctly different wave complex than those obtained under the awake condition. The P2 peak that is most prominent in the AERs obtained from awake subjects was diminished considerably under sedation and P3 became the prominent peak. Moreover, the P3 peaks in the AERs obtained under sedation were of considerably greater amplitude than the P2 peaks obtained in the awake condition. In all cases where responses were obtained from awake subjects, greater amplitude responses were obtained during sedation. The use of sedation with the preschool children proved to be most important in obtaining more detectable responses and permitting evoked potential audiometry with otherwise unmanageable children.

Wavelet Analysis of Middle Latency Auditory Evoked Responses

2001 ◽  
Vol 95 (5) ◽  
pp. 1141-1150 ◽  
Author(s):  
Eberhard Kochs ◽  
Gudrun Stockmanns ◽  
Christine Thornton ◽  
Werner Nahm ◽  
Cor J. Kalkman
Keyword(s):  
Wavelet Transform ◽  
Wavelet Analysis ◽  
Threshold Value ◽  
Evoked Responses ◽  
Verbal Command ◽  
Auditory Evoked Responses ◽  
Analysis Technique ◽  
Prediction Probability ◽  
Middle Latency ◽  
Monitoring Devices

Background Middle latency auditory evoked responses (MLAER) as a measure of depth of sedation are critically dependent on data quality and the analysis technique used. Manual peak labeling is subject to observer bias. This study investigated whether a user-independent index based on wavelet transform can be derived to discriminate between awake and unresponsive states during propofol sedation. Methods After obtaining ethics committee approval and written informed consent, 13 volunteers and 40 patients were studied. In all subjects, propofol was titrated to loss of response to verbal command. The volunteers were allowed to recover, then propofol was titrated again to the same end point, and subjects were finally allowed to recover. From three MLAER waveforms at each stage, latencies and amplitudes of peaks Pa and Nb were measured manually. In addition, wavelet transform for analysis of MLAER was applied. Wavelet transform gives both frequency and time information by calculation of coefficients related to different frequency contents of the signal. Three coefficients of the so-called wavelet detail level 4 were transformed into a single index (Db3d4) using logistic regression analysis, which was also used for calculation of indices for Pa, Nb, and Pa/Nb latencies. Prediction probabilities for discrimination between awake and unresponsive states were calculated for all MLAER indices. Results During propofol infusion, subjects were unresponsive, and MLAER components were significantly depressed when compared with the awake states (P < 0.001). The wavelet index Db3d4 was positive for awake and negative for unresponsive subjects with a prediction probability of 0.92. Conclusion These data show that automated wavelet analysis may be used to differentiate between awake and unresponsive states. The threshold value for the wavelet index allows easy recognition of awake versus unresponsive subjects. In addition, it is independent of subjective peak identification and offers the advantage of easy implementation into monitoring devices.

Middle Latency Auditory Evoked Responses in Normal Term Infants: A Longitudinal Study

1989 ◽  
Vol 20 (02) ◽  
pp. 59-63 ◽  
Author(s):  
Susan Rogers ◽  
Deborah Edwards ◽  
D. Henderson-Smart ◽  
A. Pettigrew
Keyword(s):  
Longitudinal Study ◽  
Evoked Responses ◽  
Term Infants ◽  
Auditory Evoked Responses ◽  
Normal Term ◽  
Middle Latency
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