Wideband ipsilateral measurements of middle-ear muscle reflex thresholds in children and adults

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An insert ear-canal probe including sound source and microphone can deliver a calibrated sound power level to the ear. The aural power absorbed is proportional to the product of mean-squared forward pressure, ear-canal area, and absorbance, in which the sound field is represented using forward (reverse) waves traveling toward (away from) the eardrum. Forward pressure is composed of incident pressure and its multiple internal reflections between eardrum and probe. Based on a database of measurements in normal-hearing adults from 0.22 to 8 kHz, the transfer-function level of forward relative to incident pressure is boosted below 0.7 kHz and within 4 dB above. The level of forward relative to total pressure is maximal close to 4 kHz with wide variability across ears. A spectrally flat incident-pressure level across frequency produces a nearly flat absorbed power level, in contrast to 19 dB changes in pressure level. Calibrating an ear-canal sound source based on absorbed power may be useful in audiological and research applications. Specifying the tip-to-tail level difference of the suppression tuning curve of stimulus frequency otoacoustic emissions in terms of absorbed power reveals increased cochlear gain at 8 kHz relative to the level difference measured using total pressure.

Section: Interpreting Suppression Of Sfoaes At High Frequenciesmentioning

confidence: 96%

Section: B Acoustic Transfer-function Measurementsmentioning

confidence: 99%

Specification of absorbed-sound power in the ear canal: Application to suppression of stimulus frequency otoacoustic emissions

Keefe¹,

Schairer²

2011

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“…First, unlike the MOC, we are not aware of any neural-reflex circuitry that could mediate differential MER activity under different states of attention. Second, our most important measurements were made at 4.0 kHz, and the MER primarily attenuates lower frequencies (Dallos, 1973;Goodman and Keefe, 2006;Henin et al, 2014;Schairer et al, 2007). Third, there are large individual differences in the SPLs that activate the MER (e.g., Goodman and Keefe, 2006;Henin et al, 2014), and when a 4.0-kHz tone of 80 dB was presented during the initial screening of these subjects, only three had an MER.…”

Section: F Possible Alternative Explanationsmentioning

confidence: 99%

Changes in otoacoustic emissions during selective auditory and visual attention

Walsh

Pasanen

McFadden

2015

Previous studies have demonstrated that the otoacoustic emissions (OAEs) measured during behavioral tasks can have different magnitudes when subjects are attending selectively or not attending. The implication is that the cognitive and perceptual demands of a task can affect the first neural stage of auditory processing-the sensory receptors themselves. However, the directions of the reported attentional effects have been inconsistent, the magnitudes of the observed differences typically have been small, and comparisons across studies have been made difficult by significant procedural differences. In this study, a nonlinear version of the stimulus-frequency OAE (SFOAE), called the nSFOAE, was used to measure cochlear responses from human subjects while they simultaneously performed behavioral tasks requiring selective auditory attention (dichotic or diotic listening), selective visual attention, or relative inattention. Within subjects, the differences in nSFOAE magnitude between inattention and attention conditions were about 2-3 dB for both auditory and visual modalities, and the effect sizes for the differences typically were large for both nSFOAE magnitude and phase. These results reveal that the cochlear efferent reflex is differentially active during selective attention and inattention, for both auditory and visual tasks, although they do not reveal how attention is improved when efferent activity is greater.

“…In the most commonly used condition, the noise levels were 63 and 69 dB SPL for the single-earphone and two-earphone presentations of each triplet, respectively, the larger of which is close to the nominal MER threshold for broadband noise ͑Wilson and Margolis, 1999͒. In adult ears, Shairer et al ͑2007͒ found that the range of broadband noise levels capable of eliciting a statistically significant change in acoustic admittance in the ear canal was 64-80 dB Hearing Level. These facts make it logically possible that some or all of the effects reported here were attributable to the MER rather than to cochlear mechanisms and the MOC system.…”

mentioning

confidence: 99%

“…We are not unequivocally able to rule out a potential influence of the MER on our nSFOAE measures, but several facts suggest that those influences were minimal. ͑1͒ The MER primarily acts to attenuate the transmission of low frequencies through the middle ear ͑Dallos, 1973; Goodman and Keefe, 2006;Shairer et al, 2007͒. In the present study, the frequency of the probe tone and the frequency at which the nSFOAE was measured was 4.0 kHz. Shairer et al ͑2007͒ found that above 2.0 kHz, shifts in acoustic admittance were not significantly different from zero for any level of noise activator.…”

mentioning

confidence: 99%

Properties of a nonlinear version of the stimulus-frequency otoacoustic emission

Walsh

Pasanen

McFadden

2010

A procedure for extracting the nonlinear component of the stimulus-frequency otoacoustic emission ͑SFOAE͒ is described. This nSFOAE measures the amount by which the cochlear response deviates from linear additivity when the input stimulus is doubled in amplitude. When a 4.0-kHz tone was presented alone, the magnitude of the nSFOAE response remained essentially constant throughout the 400-ms duration of the tone; response magnitude did increase monotonically with increasing tone level. When a wideband noise was presented alone, nSFOAE magnitude increased over the initial 100-to 200-ms portion of the 400-ms duration of the noise. When the tone and the wideband noise were presented simultaneously, nSFOAE magnitude decreased momentarily, then increased substantially for about the first 100 ms and then remained strong for the remainder of the presentation. Manipulations of the noise bandwidth revealed that the low-frequency components were primarily responsible for this rising, dynamic response; no rising segment was seen with bandpass or highpass noise. The rising, dynamic nSFOAE response is likely attributable to activation of the medial olivocochlear efferent system. This perstimulatory emission appears to have the potential to provide information about the earliest stages of auditory processing for stimuli commonly used in psychoacoustical tasks.