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At least 613 records · Page 34Linked to original sources
PubMed1998

Spatial aspects of reproduced sound in small rooms.

This paper reports on the influence of individual reflections on the auditory spatial aspects of reproduced sound. The sound field produced by a single loudspeaker positioned in a normal listening room has been simulated using an electroacoustical synthesis of the direct sound, 17 individual reflections and the reverberant field. The threshold of detection was measured using the method of adjustment for five reflections using three subjects for noise and speech. The thresholds have been measured for two simulated situations (1) a loudspeaker with a frequency independent directivity characteristics and frequency independent absorption coefficients of the room surfaces and (2) a loudspeaker with directivity similar to a standard two-way system and absorption coefficients according to measurements of real materials. The results have shown that subjects can reliably distinguish between timbre and spatial aspect of the sound field, that the spectral energy above 2 kHz of the individual reflection determines the importance of the reflection for the spatial aspects, and that only the first order floor reflection will contribute to the spatial aspects.

Amplifiers, Electronic↗
PubMed2000

Ultrasound sensitivity in the cricket, Eunemobius carolinus (Gryllidae, Nemobiinae).

Extracellular recordings from the cervical connectives in both long- and short-winged E. carolinus reveal auditory units that are sensitive to frequencies > 15 kHz with best sensitivity at 35 kHz (79 dB SPL threshold). Stimuli in this frequency range also elicit a startle response in long-winged individuals flying on a tether. For single-pulse stimuli, startle and neck connective thresholds decrease with increasing ultrasound duration, consistent with the operation of an exponential integrator with a approximately 32.5-ms time constant. There is evidence for adaptation to long duration pulses (> 20 ms) in the neck connectives, however, as it is more difficult to elicit responses to the later stimuli of a series. For paired-pulse stimuli consisting of 1-ms pulses of 40 kHz, temporal integration was demonstrated for pulse separations < 5 ms. For longer pulse separations, startle thresholds were elevated by 3 dB and appear to be optimally combined. Startle thresholds to 5 ms frequency modulated (FM) sweeps (60-30 kHz) and pure tone pulses (40 kHz) did not differ. The characteristics and sensitivity of this ultrasound-induced startle response did not differ between males and females. As in some other tympanate insects, ultrasound sensitivity in E. carolinus presumably functions in the context of predation from echolocating bats.

Animals↗
PubMed1984

The current status of auditory brainstem response testing in neonatal populations.

The use of auditory brainstem response (ABR) for assessment of hearing in the neonate has not been without challenge. Although numerous articles have appeared, agreement regarding the utility of neonatal ABR testing does not exist. In review of the current studies and commentaries, a clear majority are favorable to neonatal ABR testing. These studies along with current test procedures are discussed.

Audiometry↗
PubMed1989

Effects of randomizing signal level and duration on temporal gap detection.

Although discriminable changes in stimulus energy or overall duration may accompany the silent temporal gap, there is little evidence that these extraneous cues confound the measurement of temporal gap detection threshold. In this report we show that (1) under conditions where gap detection thresholds are large in relation to the duration of the standard, extraneous cues may confound gap detection leading to underestimates of the true threshold, and (2) randomization of overall stimulus level and duration can successfully remove confounding energy and duration cues without distracting the listener's attention from the temporal-gap cue.

Adult↗
PubMed2002

Asymmetry in event-related potentials to simulated auditory motion in children, young adults, and seniors.

We studied auditory evoked responses to the apparent movement of a burst of noise in the horizontal plane. Event-related potentials (ERPs) were measured in three groups of participants: children in the age range from 9 to 12 years, young adults in the age range from 18 to 34 years, and seniors in the age range from 65 to 80 years. The topographic distribution of grand-averaged ERP activity was substantially greater over the right hemisphere in children and seniors but slightly greater over the left hemisphere in young adults. This finding may be related to age-related differences in the extent to which judgments of sound movement are based on displacement versus velocity information.

Adolescent↗
PubMed2002

Auditory-visual speech perception and aging.

OBJECTIVE: This experiment was designed to assess the integration of auditory and visual information for speech perception in older adults. The integration of place and voicing information was assessed across modalities using the McGurk effect. The following questions were addressed: 1) Are older adults as successful as younger adults at integrating auditory and visual information for speech perception? 2) Is successful integration of this information related to lipreading performance? DESIGN: The performance of three groups of participants was compared: young adults with normal hearing and vision, older adults with normal to near-normal hearing and vision, and young controls, whose hearing thresholds were shifted with noise to match the older adults. Each participant completed a lipreading test and auditory and auditory-plus-visual identification of syllables with conflicting auditory and visual cues. RESULTS: The results show that on average older adults are as successful as young adults at integrating auditory and visual information for speech perception at the syllable level. The number of fused responses did not differ for the CV tokens across the ages tested. Although there were no significant differences between groups for integration at the syllable level, there were differences in the response alternatives chosen. Young adults with normal peripheral sensitivity often chose an auditory alternative whereas, older adults and control participants leaned toward visual alternatives. In additions, older adults demonstrated poorer lipreading performance than their younger counterparts. This was not related to successful integration of information at the syllable level. CONCLUSIONS: Based on the findings of this study, when auditory and visual integration of speech information fails to occur, producing a nonfused response, participants select an alternative response from the modality with the least ambiguous signal.

Acoustic Stimulation↗
PubMed2005

Individual differences in auditory processing in specific language impairment: a follow-up study using event-related potentials and behavioural thresholds.

It has frequently been claimed that children with specific language impairment (SLI) have impaired auditory perception, but there is much controversy about the role of such deficits in causing their language problems, and it has been difficult to establish solid, replicable findings in this area. Discrepancies in this field may arise because (a) a focus on mean results obscures the heterogeneity in the population and (b) insufficient attention has been paid to maturational aspects of auditory processing. We conducted a study of 16 young people with specific language impairment (SLI) and 16 control participants, 24 of whom had had auditory event-related potentials (ERPs) and frequency discrimination thresholds assessed 18 months previously. When originally assessed, around one third of the listeners with SLI had poor behavioural frequency discrimination thresholds, and these tended to be the younger participants. However, most of the SLI group had age-inappropriate late components of the auditory ERP, regardless of their frequency discrimination. At follow-up, the behavioural thresholds of those with poor frequency discrimination improved, though some remained outside the control range. At follow-up, ERPs for many of the individuals in the SLI group were still not age-appropriate. In several cases, waveforms of individuals in the SLI group resembled those of younger typically-developing children, though in other cases the waveform was unlike that of control cases at any age. Electrophysiological methods may reveal underlying immaturity or other abnormality of auditory processing even when behavioural thresholds look normal. This study emphasises the variability seen in SLI, and the importance of studying individual cases rather than focusing on group means.

Adolescent↗
PubMed2004

[Tinnitus].

Tinnitus is an auditory perception without adequate external acoustic sources. The incidence of tinnitus in the general population is high, and can lead to total decompensation in some of the affected patients. Tinnitus is a symptom of an unspecific lesion of the ear or the central auditory system. In many cases, the cause of tinnitus can be inferred from the medical history and from the results of specific medical examines. Nevertheless, in many cases there is still no causal therapy available. As a result, for most patients approaches such as proper counselling, the fitting of hearing aids or tinnitus retraining therapy are adopted.

Audiometry↗
PubMed1996

Midlatency auditory evoked potentials during anaesthesia with increasing endexpiratory concentrations of desflurane.

BACKGROUND: Under general anaesthesia with the volatile anaesthetics halothane, enflurane and isoflurane, midlatency auditory evoked potentials (MLAEP) are suppressed dose-dependently. Therefore, MLAEP have been used to measure depth of anaesthesia and to indicate intraoperative awareness. Desflurane is a new volatile anaesthetic and its effect on MLAEP have not been studied previously. METHODS: We have studied MLAEP during general anaesthesia with increasing endexpiratory concentrations of desflurane in 12 patients scheduled for elective gynaecological surgery. Auditory evoked potentials were recorded in the awake state and during anaesthesia with endexpiratory steady state concentrations of 1.5, 3.0, 4.5 and 6.0 vol % of desflurane on vertex (positive) and mastoids on both sides (negative). Latencies of the peaks V, Na, Pa, Nb, Pl (ms) and amplitudes Na/Pa, Pa/Nb and Nb/Pl (micro V) were measured. RESULTS: In the awake state, MLAEP had high peak-to-peak amplitudes and a periodic waveform. During general anaesthesia with increasing endexpiratory concentration of desflurane, the latency of the brainstem response V increased only slightly. In contrast, MLAEP showed a marked dose-dependent and statistically significant increase in latencies of Na, Pa, Nb and Pl and decrease in amplitudes of Na/Pa, Pa/Nb and Nb/Pl. Under 6.0 vol % of desflurane MLAEP were severely attenuated or even abolished. CONCLUSION: Based on these observations, endexpiratory concentrations of > or = 4.5 vol % desflurane should suppress awareness phenomena such as auditory perceptions during anaesthesia.

Adult↗
PubMed2003

Cortical sound processing in children with autism disorder: an MEG investigation.

Previous work investigating frequency encoding mechanisms in human auditory cortex has provided evidence that latency of the auditory evoked M100 is strongly proportional to frequency, with low frequency (100-200 Hz) tones associated with approximately 30 ms longer latencies than mid-range frequency (1-2 kHz) tones. Motivated by pervasive speech and auditory perception deficits observed in autism spectrum disorder, we evaluated M100 frequency dependence in children with autism disorder and typically developing controls. Results indicate that for control children, the dynamic range of frequency modulation was similar to previous reports for healthy adults. Children with autism had a much reduced range of modulation in right hemisphere sites. Findings indicate that frequency encoding mechanisms may follow a differential maturational path in autism spectrum disorder.

Acoustic Stimulation↗
PubMed1992

[Effects of high-dose fentanyl anesthesia on auditory brain stem responses].

It was previously reported that high-dose (50 micrograms.kg-1) fentanyl anesthesia had no effect on auditory brainstem response (ABR). However, the effect of the dose of 100 micrograms.kg-1 of fentanyl is unknown. We examined the effects of the dose of 50 micrograms.kg-1 and 100 micrograms.kg-1 of fentanyl on ABRs in 10 patients scheduled for cardiovascular surgery. No significant change was observed immediately after infusion of 50 micrograms.kg-1 of fentanyl, but peak latencies of waves I, III and V were significantly prolonged and the amplitude of wave V was significantly decreased immediately after infusion of 100 micrograms.kg-1 of fentanyl. The interpeak latencies of I-III and I-V were not affected. Therefore, prolongations of latencies of waves III and V were due to the change of latency of wave I. These results demonstrate that high-dose (100 micrograms.kg-1) fentanyl anesthesia depresses the peripheral auditory perception but dose not depress the central conduction.

Adult↗
PubMed2005

Bone-conduction hearing and the occlusion effect in otosclerosis and normal controls.

OBJECTIVE: The goal of this study was to better understand bone-conduction hearing in subjects with normal hearing and in those with otosclerosis through the occlusion effect. With this study, the authors hope to lend credence to commonly accepted theories of bone-conduction hearing and the effect of lateralization during the Weber tuning fork test. BACKGROUND: There are three accepted theories defining bone-conduction hearing: compressional bone conduction describes an auditory percept produced by the compression and expansion of the cochlea leading to basilar membrane vibration; inertial bone conduction describes the inertia of the ossicular chain as a result of skull vibration during bone conduction testing; whereas skull vibration may also be transmitted to the external auditory canal, surrounding soft tissues, and para-auditory structures to illicit tympanic membrane vibration known as osseotympanic bone conduction. METHODS: Twenty normal volunteers and 17 unilateral otosclerosis patients underwent external canal sound pressure level measurement during bone-conduction testing using a standardized bone oscillator placement and stimulation paradigm. Sound was detected with a probe microphone placed in the external auditory canal in nonoccluded and occluded conditions after a 50-dB hearing level bone-conduction stimulus. RESULTS: There was no significant difference in sound pressure level between otosclerosis and normal subjects when the external auditory canals were nonoccluded. With occlusion, sound pressure level increased in both groups, but at a statistically significantly higher level for the otosclerosis group. CONCLUSION: Sound measured in the external canal likely represents energy lost to the environment transmitted through the middle and external ear systems, aided by the effect of both inertial and osseotympanic bone conduction. Occluding the ear leads to sound trapping and amplification. Also, the pressure exerted against the tympanic membrane reduces middle ear compliance and increases the impedance mismatch between air and the middle ear system, reflecting sound back into the external canal. This effect is further enhanced by stapes fixation to explain our data in both groups of subjects. The final common pathway in "lateralization" is probably a product of higher than normal impedance mismatch at the oval window.

Auditory Threshold↗
PubMed2006

Amplitude and phase dynamics associated with acoustically paced finger tapping.

To gain insight into the brain activity associated with the performance of an acoustically paced synchronization task, we analyzed the amplitude and phase dynamics inherent in magnetoencephalographic (MEG) signals across frequency bands in order to discriminate between evoked and induced responses. MEG signals were averaged with respect to motor and auditory events (tap and tone onsets). Principal component analysis was used to compare amplitude and phase changes during listening and during paced and unpaced tapping, allowing a separation of brain activity related to motor and auditory processes, respectively. Motor performance was accompanied by phasic amplitude changes and increased phase locking in the beta band. Auditory processing of acoustic stimuli resulted in a simultaneous increase of amplitude and phase locking in the theta and alpha band. The temporal overlap of auditory-related amplitude changes and phase locking indicated an evoked response, in accordance with previous studies on auditory perception. The temporal difference of movement-related amplitude and phase dynamics in the beta band, on the other hand, suggested a change in ongoing brain activity, i.e., an induced response supporting previous results on motor-related brain dynamics in the beta band.

Acoustic Stimulation↗
PubMed1995

The effects of anesthesia with increasing end-expiratory concentrations of sevoflurane on midlatency auditory evoked potentials.

We studied midlatency auditory evoked potentials (MLAEP) during general anesthesia with increasing end-expiratory concentrations of sevoflurane in 12 patients scheduled for elective gynecologic surgery. After oral premedication with 20 mg clorazepate dipotassium, anesthesia was induced with etomidate (0.2 mg/kg intravenously [IV]). Vecuronium (0.1 mg/kg) was given for neuromuscular block, and controlled ventilation with sevoflurane in 100% O2 was instituted. Auditory evoked potentials were recorded in the awake state and during anesthesia with end-expiratory steady-state concentrations of 0.5, 1.0, 1.5, and 2.0 vol% of sevoflurane on vertex (positive) and mastoids on both sides (negative). Latencies of peaks V, Na, Pa, Nb, and P1 (ms) and amplitudes of Na/Pa, Pa/Nb, and Nb/P1 (microV) were measured. In the awake state, MLAEP had high peak-to-peak amplitudes and a periodic waveform. During general anesthesia with increasing end-expiratory concentrations of sevoflurane, the latency of the brainstem response V increased slightly. In contrast, MLAEP showed marked dose-dependent, statistically significant increases in the latencies of Na, Pa, Nb, and P1 and decreases in the amplitudes of Na/Pa, Pa/Nb, and Nb/P1. Under 2 vol% of sevoflurane, MLAEPs were severely attenuated or abolished. Based on these observations, > or = 1.5 vol% sevoflurane should suppress phenomena such as auditory perceptions, intraoperative wakefulness, and awareness.

Adult↗
PubMed2005

Aversion, awareness, and attraction: investigating claims of hyperacusis in the Williams syndrome phenotype.

BACKGROUND: Williams syndrome (WS), a neurodevelopmental disorder, is characterized by pervasive cognitive deficits alongside a relative sparing of auditory perception and cognition. A frequent characteristic of the phenotype is adverse reactions to, and/or fascination with, certain sounds. Previously published reports indicate that people with WS experience hyperacusis, yet careful examination reveals that the term 'hyperacusis' has been used indiscriminately in the literature to describe quite different auditory abnormalities. METHOD: In an effort to clarify and document the incidence of auditory abnormalities in and among people with WS we collected data from parents of people with WS (n = 118) and comparison groups of people with Down syndrome, autism, and normal controls. RESULTS: Our findings revealed four phenomenologically separate auditory abnormalities, all of which were significantly more prevalent in WS than the three comparison groups. Among people with WS, we found relatively few reports of true hyperacusis (lowered threshold for soft sounds) or auditory fascinations/fixations, whereas 80% reported fearfulness to idiosyncratically particular sounds, and 91% reported lowered uncomfortable loudness levels, or 'odynacusis.' CONCLUSIONS: Our results confirm anecdotal reports of an unusual auditory phenotype in WS, and provide an important foundation for understanding the nature of auditory experience and pathology in WS. We conclude by reviewing the ways in which the present findings extend and complement recent neuroanatomical and neurophysiological findings on auditory function in people with WS.

Awareness↗
PubMed1996

[Reaction times at auditory threshold: a comparison of normal hearing probands and patients with hearing damage].

BACKGROUND: The purpose of the study was to examine the latencies between tonal stimuli and response of normal ears at the threshold compared with ears with a frequency-specific threshold above 70 dB. PATIENTS AND METHODS: Reaction times to tonal stimuli of 122 adults with normal hearing and adults with hearing loss were compared at the threshold of hearing to reaction times beyond the threshold. The study group of tested patients was divided into four groups corresponding to the frequency-specific hearing loss on the basis of previous audiometric investigations. RESULTS: The results reveal that response latencies in ears with normal hearing asymptomatically approach the auditory threshold. In contrast, we failed to measure a significant prolongation of reaction times in presence of extensive hearing loss (above 70 dB) even at the minimum level of auditory perception. In the presence of extensive hearing loss (above 70 dB), we detected a significantly lower rise of threshold response latencies at normal audiometric frequencies than in normal ears. CONCLUSION: The reaction time results are evaluated, and the possible role of the outer hair cells are discussed.

Adult↗