scholarly journals Auditory Attention Reduced Ear-Canal Noise in Humans by Reducing Subject Motion, Not by Medial Olivocochlear Efferent Inhibition: Implications for Measuring Otoacoustic Emissions During a Behavioral Task

Author(s):  
Nikolas A. Francis ◽  
Wei Zhao ◽  
John J. Guinan Jr.
2018 ◽  
Author(s):  
Nikolas A. Francis ◽  
Wei Zhao ◽  
John J. Guinan

AbstractOtoacoustic emissions (OAEs) are often measured to non-invasively determine activation of medial olivocochlear (MOC) efferents in humans. Usually these experiments assume that ear-canal noise remains constant. However, changes in ear-canal noise have been reported in some behavioral experiments. We studied the variability of ear-canal noise in eight subjects who performed a two-interval-forced-choice (2IFC) sound-level-discrimination task on monaural tone pips in masking noise. Ear-canal noise was recorded directly from the unstimulated ear opposite the task ear. Recordings were also done with similar sounds presented, but no task done. In task trials, ear-canal noise was reduced at the time the subject did the discrimination, relative to the noise level earlier in the trial. In two subjects, there was a decrease in ear-canal noise, primarily at 1-2 kHz, with a time course similar to that expected from inhibition by MOC activity elicited by the task-ear masker noise. These were the only subjects with spontaneous OAEs (SOAEs). We hypothesize that the SOAEs were inhibited by MOC activity elicited by the task-ear masker. Based on the standard rationale in OAE experiments that large bursts of noise are artifacts due to subject movement, noise bursts above a sound-level criterion were removed. As the criterion was lowered and more high-and moderate-level noise bursts were removed, the reduction in noise level from the beginning of the trial to the time of the 2IFC discrimination became less. This pattern is opposite that expected from MOC inhibition (which is greater on lower-level sounds), but can be explained by the hypothesis that subjects move less and create fewer bursts of noise when they concentrate on doing the task. In contrast, for the six subjects with no SOAEs, in no-task trials the noise level was little changed throughout the trial. Our results show that measurements of MOC effects on OAEs must measure and account for changes in ear-canal noise, especially in behavioral experiments. The results also provide a novel way of showing the time course of the buildup of attention in ear-canal noise during a 2IFC task.


2013 ◽  
Vol 133 (4) ◽  
pp. EL331-EL337 ◽  
Author(s):  
Makram Zebian ◽  
Volker Schirkonyer ◽  
Johannes Hensel ◽  
Sven Vollbort ◽  
Thomas Fedtke ◽  
...  

2013 ◽  
Vol 34 (5) ◽  
pp. 784-789 ◽  
Author(s):  
Erdem Eren ◽  
Ece Harman ◽  
Seçil Arslanoğlu ◽  
Kazm Önal ◽  
Hüseyin Katlmiş

2006 ◽  
Vol 119 (6) ◽  
pp. 3896-3907 ◽  
Author(s):  
Tiffany A. Johnson ◽  
Stephen T. Neely ◽  
Judy G. Kopun ◽  
Michael P. Gorga

Author(s):  
Shawn Goodman ◽  
Sriram Boothalingam ◽  
Jeffery T Lichtenhan

Functional outcomes of medial olivocochlear reflex (MOCR) activation, such as improved hearing in background noise and protection from noise damage, involve moderate to high sound levels. Previous noninvasive measurements of MOCR in humans focused primarily on otoacoustic emissions (OAEs) evoked at low sound levels. Interpreting MOCR effects on OAEs at higher levels is complicated by the possibility of the middle-ear muscle reflex and by components of OAEs arising from different locations along the length of the cochlear spiral. We overcame these issues by presenting click stimuli at a very slow rate and by time-frequency windowing the resulting click-evoked (CE)OAEs into short-latency (SL) and long-latency (LL) components. We characterized the effects of MOCR on CEOAE components using multiple measures to more comprehensively assess these effects throughout much of the dynamic range of hearing. These measures included CEOAE amplitude attenuation, equivalent input attenuation, phase, and slope of growth functions. Results show that MOCR effects are smaller on SL components than LL components, consistent with SL components being generated slightly basal of the characteristic frequency region. Amplitude attenuation measures showed the largest effects at the lowest stimulus levels, but slope change and equivalent input attenuation measures did not decrease at higher stimulus levels. These latter measures are less commonly reported and may provide insight into the variability in listening performance and noise susceptibility seen across individuals.


2014 ◽  
Vol 150 (6) ◽  
pp. 1033-1039 ◽  
Author(s):  
Erdem Eren ◽  
Ece Harman ◽  
Seçil Arslanoğlu ◽  
Kazım Önal

2014 ◽  
Vol 25 (04) ◽  
pp. 343-354 ◽  
Author(s):  
Venkatesh Aithal ◽  
Joseph Kei ◽  
Carlie Driscoll ◽  
Andrew Swanston ◽  
Katrina Roberts ◽  
...  

Background: Diagnosing middle ear disorders in neonates is a challenging task for both audiologists and otolaryngologists. Although high-frequency (1000 Hz) tympanometry and acoustic stapedial reflex tests are useful in diagnosing middle ear problems in this age group, they do not provide information about the dynamics of the middle ear in terms of its resonance frequency (RF) and mobility. The sweep frequency impedance (SFI) test can provide this information, which may assist in the diagnosis of middle ear dysfunction in neonates. Purpose: This study aimed to investigate the feasibility of testing neonates using the SFI technique, establish normative SFI data for RF and mobility of the middle ear in terms of changes in sound pressure level (ΔSPL in dB), and describe the dynamics of the middle ear in healthy Australian neonates. Study Sample: A prospective sample of 100 neonates (58 males, 42 females) with a mean gestational age of 39.3 wk (SD = 1.3 wk; range = 38–42 wk), who passed all three tests, namely, automated auditory brainstem response, transient evoked otoacoustic emissions, and 1000 Hz tympanometry, were included in this study. Data Collection and Analysis: A SFI research prototype was used to collect the data. First, the SPL in the ear canal was measured as a probe-tone frequency was swept from 100–2000 Hz with the ear canal static pressure held constant at 200 daPa. Then, this measurement was repeated with the static pressure reduced in 50 daPa steps to –200 daPa. Additional measurement was also performed at the static pressure, where the peak of the 1000 Hz tympanogram occurred. A graph showing the variation of SPL against frequency at all static pressures was plotted. From this graph, the RF and ΔSPL at tympanometric peak pressure (TPP) were determined. Descriptive statistics and an analysis of variance (ANOVA) were applied to the RF and ΔSPL data with gender and ear as independent variables. Results: The results showed two resonance regions of the outer/middle ear with the high RF (mean = 1236 Hz; 90% range: 830–1518 Hz) being approximately equal to four times that of the low RF (mean = 287 Hz; 90% range = 209–420 Hz). The low RF was more easily identifiable than the high RF. The ΔSPL at the low RF (mean = 8.2 dB; 90% range = 3.4–13 dB) was greater than that at the high RF (mean = 5.0 dB; 90% range = 1.5–8.1 dB). There were no significant differences or interactions between genders and ears. Conclusion: The study showed that the SFI is a feasible test of middle ear function in neonates. The SFI results revealed two regions of resonance with the lower resonance (287 Hz) possibly related to the movements of the outer ear canal wall and higher resonance (1236 Hz) related to the resonance of the middle ear. The normative data developed in this study will be useful in evaluating outer and middle ear function in neonates.


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