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Results for “Loudness Perception”

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PubMed2006

Bandwidth determines modulatory effects of centrifugal pathways on cochlear hearing desensitization caused by loud sound.

Centrifugal olivocochlear (OC) pathways modulate cochlear hearing losses induced in cats by loud sounds varying in bandwidth from tones to clicks and noise bands, in a variety of conditions. The general effect, always to reduce hearing damage, can be a net effect resulting from complex interactions between OC subcomponents (crossed and uncrossed OC pathways). The interactions between these subcomponents vary with type of loud sound, suggesting that sound bandwidth may be important in determining how OC pathways modulate loud sound-induced hearing loss. This dependency was examined and here it is reported that OC pathways do not alter cochlear hearing losses caused by loud noise with a 2-kHz-wide bandwidth intermediate between the loud sounds of previous studies. Increasing stimulus bandwidth even slightly more, to use a loud 3.5-kHz-wide bandwidth noise as the damaging sound, once again revealed OC modulation of cochlear hearing loss. The fact that OC pathways do not modulate cochlear hearing losses induced by loud 2-kHz-wide noise was demonstrated in three very different test conditions in which OC pathways modulate hearing losses caused by narrower or broader bandwidth sounds. This confirmed that the absence of centrifugal modulation of hearing loss to this particular sound was a robust phenomenon not related to test condition. The absence of overall centrifugal effects was also true at the level of subcomponent pathways; neither crossed nor uncrossed OC pathways individually modulated cochlear hearing losses to the loud 2-kHz-wide noise. This surprising frequency dependency has general implications for centrifugal modulation of cochlear responses.

Acoustic Stimulation↗
PubMed1990

Facial reactions to auditory stimuli: sex differences.

This study explored whether males and females differ in facial muscle activity when exposed to tone stimuli with different intensity. Males and females were repeatedly exposed to 95 dB and 75 dB 1000 Hz tones while their facial electromyographic (EMG) activity from corrugator and zygomatic muscle regions were measured. Skin conductance responses were also measured. It was found that 95 dB but not 75 dB tones evoked increased corrugator activity. This effect differed significantly between males and females. Thus, it was only females that reacted with a significant increased corrugator response to the high intensity tone. While facial responses differed between the sexes, the skin conductance response patterns did not. Consistent with previous research it is concluded that females are more facially expressive than are males.

Adult↗
PubMed1989

Event-related brain potentials reflecting processing of relevant and irrelevant stimuli during selective listening.

Event-related brain potentials were recorded from the human scalp during selective listening to tone pips differing in location and/or pitch from irrelevant tones. The subjects' task was to discriminate infrequent deviant tones of lower intensity appearing among designated (relevant) tones. A large processing negativity was observed in the event-related potentials to relevant tones differing from the irrelevant tones in location even when both tones randomly varied in pitch. Similarly, a large processing negativity was elicited by the relevant tones differing from the irrelevant tones in pitch even when the location of both tones varied randomly. The results support the theory that the processing negativity to relevant stimuli reflects a match of these stimuli with an "attentional trace," an actively maintained neuronal representation of the physical feature(s) of relevant stimuli that distinguish these stimuli from the irrelevant stimuli. Furthermore, the infrequent lower-intensity tones appearing among irrelevant tones elicited a mismatch negativity similar to the mismatch negativity elicited by target tones, equivalent lower-intensity tones appearing among relevant tones. This indicates that these infrequent stimulus changes were automatically discriminated by the generator mechanism associated with mismatch negativity.

Adult↗
PubMed1989

Orienting in schizophrenia: habituation to auditory stimuli of constant and varying intensity in patients high and low in skin conductance responsivity.

Groups of schizophrenics and normal controls were exposed to different series of tones of constant (80dB) and variable intensity (60, 80, and 100 dB). Measurements included bilateral skin conductance, finger pulse volume, and heart rate. Both groups were split on the common median in skin conductance response to constant intensity tones to form matched patient and control groups of low and high responsivity. The low and high responsive schizophrenic groups were more clearly separated than the two control groups in rate of spontaneous skin conductance fluctuations, skin conductance magnitudes, and skin conductance levels, primarily because of generalized hyperactivity in high responsive patients. This pattern was clearest for the most intense tone and left hand recordings. High responsive schizophrenics also showed larger response amplitudes, shorter rise and recovery times, and a smaller ratio of elicited to spontaneous responses, than high responsive controls. Finger pulse volume responses recorded from the left hand were smaller in the patient groups, whereas patients and controls did not differ in right hand recordings. High skin conductance responsive subjects showed more heart rate deceleration than low responsive subjects, and schizophrenics had more decelerative responses than controls.

Adult↗
PubMed1990

Cross-modal selective attention effects on retinal, myogenic, brainstem, and cerebral evoked potentials.

Short latency evoked potentials were recorded during a cross-modal selective attention task to evaluate recent proposals that sensory transmission in the peripheral auditory and visual pathways can be modified selectively by centrifugal mechanisms in humans. Twenty young adult subjects attended in turn to either left-ear tones or right-field flashes presented in a randomized sequence, in order to detect infrequent, lower-intensity targets. Attention-related enhancement of longer-latency components, including the visual P105 and the auditory N1/Nd waves and T-complex, showed that subjects were able to adopt a selective sensory set toward either modality. Neither the auditory evoked brainstem potentials nor the early visual components (electroretinogram, occipito-temporal N40, P50, N70 waves) were significantly affected by attention. Measures of retinal B-waves were significantly reduced in amplitude when attention was directed to the flashes, but concurrent recordings of eyelid electromyographic activity and the electro-oculogram indicated that this effect may have resulted from contamination of the retinal recordings by blink microreflex activity. A trend toward greater positivity in the 15-50 ms latency range for auditory evoked potentials to attended tones was observed. These results provide further evidence that the earliest levels of sensory transmission are unaffected by cross-modal selective attention, but that longer latency exogenous and endogenous potentials are enhanced to stimuli in the attended modality.

Adolescent↗
PubMed1990

The effect of small variation of the frequent auditory stimulus on the event-related brain potential to the infrequent stimulus.

We investigated whether the mismatch process between a rare stimulus and the trace of the frequent stimulus, which generates the mismatch-negativity component of the event-related potential, can tolerate a small variation in the intensity of the frequent stimulus. Series of short tone pips were presented to 10 subjects while they were reading a book and ignoring the auditory stimuli. The intensity (mean 80dB) of the frequent stimulus (600 Hz) varied within a range that was different in different blocks. The probability of the infrequent stimuli which were, in different blocks, either intensity deviants (600 Hz/70dB) or frequency deviants (650 Hz/80dB) was 10%. Both deviant stimuli elicited mismatch negativity even when the intensity of the frequent stimulus varied, although the amplitude of this component decreased with the increasing variability of the frequent stimulus. These results show that the generator process of mismatch negativity tolerates some variation in the repetitive stimulus, thus indicating that this process is also activated in ecologically more valid conditions. This is crucial to the interpretation of the generator process of mismatch negativity as a biologically vital warning mechanism.

Adult↗
PubMed1991

Probing the time-course of the auditory oddball P3 with secondary reaction time.

An elementary neural model of the P3 is proposed in which the P3 is held to manifest a brief, widely-distributed, inhibitory event. A preliminary and indirect test of the model is described using secondary-task methodology. Manual reaction times were measured to probe clicks delivered during the presumed time-course of an auditory oddball P3. We observed that reaction times to probes presented after oddball stimuli were significantly slowed as compared to reaction times to probes presented after standards. The latency of maximum reaction time slowing corresponded generally to the latency of the P3. The latency of maximum reaction time slowing did not respond to a manipulation varying the latency of the P3. Thus, some of the obtained results were consistent with the P3-inhibition hypothesis, whereas others were not. Secondary-task methodology may provide a valuable new approach to understanding the late event-related potentials.

Adult↗
PubMed1991

The startle eyeblink response to low intensity acoustic stimuli.

Four experiments were conducted to investigate the acoustic startle response to stimuli of low intensities. Eyeblink responses (integrated EMG from orbicularis oculi) were measured from male and female college students. Experiment 1 compared tone and noise stimuli varying in intensity (50 and 60 dB(A) SPL), with noise stimuli producing greater response amplitude and probability than tone stimuli. Experiment 2 was designed to investigate temporal summation of low intensity stimuli using single and paired 70dB(A) SPL broadband noises, and an onset-to-onset interval between the brief stimuli in a pair equal to the duration of the single stimuli. Increasing the duration of single stimuli resulted in larger responses, illustrating temporal summation. Experiment 3 used 60 and 70 dB(A) SPL broadband noise varying in rise/fall time, with faster-rising stimuli producing larger responses, and more intense stimuli producing larger and more probable responding. Experiment 4 employed the startle modification paradigm using 60 and 70 dB(A) SPL broadband noises as startle stimuli and a 50dB(A) SPL tone as a prepulse. Response amplitude and probability to both 60 and 70 dB(A) SPL stimuli were significantly inhibited by the 50dB(A) SPL prepulse. These studies show that the acoustic startle response is more sensitive than previously thought, and the elicitation of startle by low intensity stimuli argues against the limitation of the startle reflex as a high intensity phenomenon. These findings can increase the application of this response system by showing that startle stimuli need not be of high intensity, because reliable and differential startle can be elicited and modified at relatively low stimulus intensities.

Adolescent↗
PubMed1993

Lead stimulation effects on reflex blink, exogenous brain potentials, and loudness judgments.

Prepulse inhibition of the reflex blink by a weak stimulus shortly preceding a blink-eliciting stimulus has been described as a sensorimotor gating phenomenon that may protect processing of the first stimulus. To determine how a stimulus configuration that elicits prepulse inhibition also affects exogenous evoked potentials and perceived loudness of the paired stimuli, the three types of response were recorded simultaneously under four conditions: tone pairs of 75-110 dB and 75-75 dB and single control tones of each intensity. Two studies using different intrapair intervals found that blinks and exogenous potentials peaking after 50 ms were smaller for the second tone of pairs than for equal-intensity single tones. Pairing also reduced the loudness of 110-dB second tones, but the loudness of 75-dB first and second tones was unaffected or increased. These effects are discussed in terms of parallel processing of transient, unmodulated information in specific paths, steady-state modulated information in nonspecific paths, and a context-dependent effect on loudness judgments.

Acoustic Stimulation↗