[Auditory evoked potentials and perception of a moving auditory image in patients with epileptic damage in the temporal lobe of the brain].
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Adolescent↗
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Results for “Auditory Perception”
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[Change in the threshold of hearing based on air conductivity with simultaneous auditory and vibration perception].
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Auditory Perception↗
[Explantation of residual effect].
The direct spatial-temporal description of oscillations of the internal ear basilar membrane, arbitrarily called "oscillographic vision" of these oscillations, made it possible to create a model for two systems of auditory perception of sound pitch [1]. On the basis of this model, the residual effect is explained by the action of the main system, the system of periodicity analysis. A procedure of calculating the zone of occurrence of the residuum is described. The predominance of the complex of low-frequency constituents of the residual sound is explained. A qualitative and a quantitative description of high-frequency rectangular pulse shifts induced by the action of the fine structure of these pulses are given. The assumption is made that these results can be used for comparing the accuracy of the two systems of sound pitch perception.
Auditory Perception↗
Representation of acoustic events in the primary auditory cortex.
One approach to the problem of specifying the contribution of the primary auditory cortex to auditory perception has been based on single-neuron recording techniques in animals. These experiments measure the response rates of individual neural elements to parametric variations in 1 or more stimulus dimensions. The patterns of response rates and response failures revealed by these manipulations are quantitative descriptions of the form and fidelity of the cortex's representation of those stimulus dimensions. This strategy has been used to advantage in studies of the cortical representation of the spectral content of auditory events, the spatial location of a sound, and the time structure of sounds. The data constitute new links between neural coding and behavioral performance in normal and impaired listeners.
Animals↗
Stimulation of the cochlear nucleus with multichannel auditory brainstem implants and long-term results: Freiburg patients.
Since 1992 18 patients with bilateral retrocochlear deafness have been provided with a multichannel auditory brainstem implant (ABI). The surgical procedure implies tumour removal and ABI implantation in one stage. Most implantations were via the translabyrinthine approach. The long-term follow-up varied between nine and 80 months. In one case auditory perception could not be achieved and in a second case post-operative stimulation was not possible as the subject died due to lung emboli. In all the other cases auditory perception was achieved and only two subjects became non-users during the follow-up period. The presented long-term results suggest that deaf neurofibromatosis type 2 patients regain acoustic contact with the environment, enlarge their communication skills and improve their quality of life by using a multichannel auditory brainstem prosthesis.
Adolescent↗
Systematic distortions of auditory space perception following prolonged exposure to broadband noise.
Perceptual distortions referred to as aftereffects may arise following exposure to an adapting sensory stimulus. The study of aftereffects has a long and distinguished history [Kohler and Wallach, Proc. Am. Philos. Soc. 88, 269-359 (1944)] and a range of aftereffects have been well described in sensory modalities such as the visual system [Barlow, in Vision: Coding and Efficiency (Cambridge University Press, Cambridge, 1990)]. In the visual system these effects have been interpreted as evidence for a population of cells or channels specific for certain features of a stimulus. However there has been relatively little work examining auditory aftereffects, particularly in respect of spatial location. In this study we have examined the effects of a stationary adapting noise stimulus on the subsequent auditory localization in the vicinity of the adapting stimulus. All human subjects in this study were trained to localize short bursts of noise in a darkened anechoic environment. Adaptation was achieved by presenting 4 min of continuous noise at the start of each block of trials and was maintained by a further 15-s noise burst between each trial. The adapting stimulus was located either directly in front of the subject or 30 degrees to the right of the midline. Subjects were required to determine the location of noise burst stimuli (150 ms) in the proximity of the adapting stimulus following each interstimulus period of adaptation. Results demonstrated that following adaptation there was a general radial displacement of perceived sound sources away from the location of the adapting stimulus. These data are more consistent with a channel-based or place-based process of sound localization rather than a simple level-based adaptation model. A simple "distribution shift" model that assumes an array of overlapping spatial channels is advanced to explain the psychophysical data.
Adult↗
Auditory intensity perception: successive versus simultaneous, across-channel discriminations.
This study measures the ability of observers to compare the intensities of two stimuli occupying different frequency regions. It includes three experiments, each experiment having two conditions. In one condition, the two stimuli to be compared were presented simultaneously within each interval; this condition has been called profile analysis. In the other condition, the two stimuli were presented successively within each interval. Because the overall level of the stimuli was randomized between intervals, the observers were encouraged to compare the intensities of the two stimuli within each observation interval rather than between intervals. The stimuli were two simple tones in experiment 1 and two tonal complexes in both experiments 2 and 3. The stimuli used in experiments 2 and 3 differed in frequency. The results show that simultaneous comparisons are superior to successive comparisons. For simple tones, the difference in threshold is about 8 dB; for complexes with 10 to 11 components, the difference in threshold is about 15 dB. These differences can be explained by assuming that internal noises in different channels were partially correlated when stimuli in those channels were presented simultaneously and were independent when the stimuli were presented successively. Cancellation of the correlated noise is therefore possible with simultaneous comparisons, making such discrimination better than that achievable with successive comparisons.
Acoustic Stimulation↗
Deficit of auditory space perception in patients with visuospatial neglect.
There have been many studies of visuospatial neglect, but fewer studies of neglect in relation with other sensory modalities. In the present study we investigate the performance of six right brain damaged (RBD) patients with left visual neglect and six RBD patients without neglect in an auditory spatial task. Previous work on sound localisation in neglect patients adopted measure of sound localisation based on directional motor responses (e.g., pointing to sounds) or judgement of sound position with respect to the body midline (auditory midline task). However, these measures might be influenced by non-auditory biases related with motor and egocentric components. Here we adopted a perceptual measure of sound localisation, consisting in a verbal judgement of the relative position (same or different) of two sequentially presented sounds. This task was performed in a visual and in a blindfolded condition. The results revealed that sound localisation performance of visuospatial neglect patients was severely impaired with respect to that of RBD controls, especially when sounds originated in contralesional hemispace. In such condition, neglect patients were always unable to discriminate the relative position of the two sounds. No difference in performance emerged as a function of the visual condition in either group. These results demonstrate a perceptual deficit of sound localisation in patients with visuospatial neglect, suggesting that the spatial deficits of these patients can arise multimodally for the same portion of external space.
Adult↗
[Awareness with recall during general anesthesia: analysis of 2015 cases].
OBJECTIVE: To investigate the incidence of awareness with recall during general anesthesia in elective operation with modern anesthetic methods and to analyze the risk factors thereof. METHODS: 2025 patients, 1001 males and 1024 females, aged 53 +/- 16, underwent general anesthesia during different kinds of elective operation. Interview was conducted 1 - 3 days postoperatively to survey the incidence of awareness during operation. Two weeks later follow-up was conducted again to know if sequelae existed. RESULTS: Twenty-eight patients (1.4%) were identified as with awareness. Multiple regression analysis showed that awareness during operation was associated with being female (OR = 2.836, 95% CI = 1.81 - 6.810), use of laryngeal mask airway (LMA, OR = 19.609, 95% CI = 3.918 - 98.740), not use volatile anesthetics at a time or continuously during maintenance of anesthesia (OR = 3.084, 95% CI = 1.246 - 7.629), and intra-operative blood pressure fluctuation (OR = 10.430, 95% CI = 3.918 - 27.763), Premedicated patients had lower incidence of awareness during operation (OR = 0.326, 95% CI = 0.110 - 0.965). Twenty-three of the 28 patients with awareness during operation (82%) had auditory perception, 2 (7%) had both auditory and visual perception, 7 felt pain at different degrees, and 10 (36%) felt anxiety during operation. After effects appeared in 6 of the 28 patients (21%). CONCLUSION: Awareness occurs in some patients undergoing elective operation. Being female, use of LMA, not using volatile anesthetics at a time or continuously during maintenance of anesthesia, and intra-operative blood pressure fluctuation are risk factors. Premedication may help prevent awareness during operation.
Anesthesia, General↗
[Comparison between the old and new evaluation mode in the dichotic discrimination test].
The dichotic discrimination test for children could make an important contribution to the diagnosis of central auditory processing disorders. With previous test procedures and their interpretation it was not possible to get the auditory discrimination ability in only one grade. To evaluate this ability, it was necessary to measure the degree of comprehension in each ear as well as the required noise level. The evaluation cannot be used for statistical results because there are too many parameters. Moreover, results apparently similar can come from varying abilities. We are therefore working on a new method to evaluate dichotic hearing more accurately. By using a constant noise level and only evaluating positively those hearing pairs which have been repeated correctly, we arrive at one single grade. The dichotic discrimination test was administered to 46 children with auditory perception disorders and the results evaluated according to both, the previous and new evaluation system. According to the new evaluation, a maximum of 20 correct responses is possible. The average number of correct responses was significantly lower than by the previous evaluation system. The standard deviation increased from 16% on the left side and 13% in the right to 24%, or five word-pairs. The difference is even clearer when the test is subdivided into four performance ranges, each of 25%. Of all the children examined, 85% fell in the upper performance range according to the previous evaluation. No child was in the lowest performance range. According to the new evaluation, only 56.5% of the children were in the upper performance range, while three children, that is 6.5%, were in the lowest performance range. This difference, P = 0.0002, is highly significant. Our results demonstrate clearly that on the basis of the new evaluation system the measurement of dichotic ability is possible, for the first time. We consider the new evaluation method to be an improvement in determining dichotic discrimination and in comparing it with other abilities. To check the validity, further independent testing should be carried out and results compared with those obtained from children without auditory perception disorders.
Auditory Perceptual Disorders↗
Auditory affect perception in a dichotic listening paradigm as a function of verbal fluency classification.
This study evaluated cerebral asymmetry for affect perception as a function of fluency classification. After being assigned to a fluency category using scores on the FAS test (Borkowski, Benton, & Spreen, 1967), forty-five right-handed subjects with normal auditory acuity listened to the Bryden and MacCrae (1989) Dichotic Emotional Words Tape. Subjects higher in fluency exhibited significantly greater right and left ear advantages than subjects lower in fluency. Conversely, REA scores for words were significantly greater than REA scores for affect, while LEA scores for affect were significantly greater than LEA scores for words.
Adult↗
Predicting the threshold of pulse-train electrical stimuli using a stochastic auditory nerve model: the effects of stimulus noise.
The incorporation of low levels of noise into an electrical stimulus has been shown to improve auditory thresholds in some human subjects (Zeng et al., 2000). In this paper, thresholds for noise-modulated pulse-train stimuli are predicted utilizing a stochastic neural-behavioral model of ensemble fiber responses to bi-phasic stimuli. The neural refractory effect is described using a Markov model for a noise-free pulse-train stimulus and a closed-form solution for the steady-state neural response is provided. For noise-modulated pulse-train stimuli, a recursive method using the conditional probability is utilized to track the neural responses to each successive pulse. A neural spike count rule has been presented for both threshold and intensity discrimination under the assumption that auditory perception occurs via integration over a relatively long time period (Bruce et al., 1999). An alternative approach originates from the hypothesis of the multilook model (Viemeister and Wakefield, 1991), which argues that auditory perception is based on several shorter time integrations and may suggest an NofM model for prediction of pulse-train threshold. This motivates analyzing the neural response to each individual pulse within a pulse train, which is considered to be the brief look. A logarithmic rule is hypothesized for pulse-train threshold. Predictions from the multilook model are shown to match trends in psychophysical data for noise-free stimuli that are not always matched by the long-time integration rule. Theoretical predictions indicate that threshold decreases as noise variance increases. Theoretical models of the neural response to pulse-train stimuli not only reduce calculational overhead but also facilitate utilization of signal detection theory and are easily extended to multichannel psychophysical tasks.
Algorithms↗
Visual speech perception without primary auditory cortex activation.
Speech perception is conventionally thought to be an auditory function, but humans often use their eyes to perceive speech. We investigated whether visual speech perception depends on processing by the primary auditory cortex in hearing adults. In a functional magnetic resonance imaging experiment, a pulse-tone was presented contrasted with gradient noise. During the same session, a silent video of a talker saying isolated words was presented contrasted with a still face. Visual speech activated the superior temporal gyrus anterior, posterior, and lateral to the primary auditory cortex, but not the region of the primary auditory cortex. These results suggest that visual speech perception is not critically dependent on the region of primary auditory cortex.
Acoustic Stimulation↗
Open set speech perception with auditory brainstem implant?
OBJECTIVE: Only a small percentage of auditory brainstem implant (ABI) recipients treated for neurofibromatosis type 2 (NF2) have proved capable of identifying words using only the sound from the ABI. Recently, the ABI was applied to a series of patients with no cochlear nerve or with cochlear disorders that could not benefit from a cochlear implant (i.e., cochlear nerve aplasia or posttraumatic avulsion) or whose benefit was or would be severely compromised. A significant number of these patients have proven capable of understanding speech, including effortless telephone use. In the present study, a series of psychophysical tests were administered to determine the cause of the difference in performance between tumor (T) and nontumor (NT) ABI patients. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Twenty patients with ABIs participated in the investigation. Ten were NF2 patients and 10 NT subjects. Patient ages ranged from 24 to 61 years. Eleven were males and nine females. INTERVENTION: Auditory rehabilitation in auditory disconnection caused by cochlea or cochlear nerve disorders. RESULTS: There was a significant correlation between modulation detection thresholds and speech understanding and a significant difference in modulation detection between T and NT patients. CONCLUSIONS: The difference in modulation detection between the two groups suggests a difference in the survival of specific cells in the cochlear nucleus that support modulation. The pattern of results indicates a separate pathway of auditory processing that is specialized for modulated sounds, and that pathway is critical for speech understanding. In NF2 patients, the tumor and surgery may selectively damage this pathway, resulting in poor speech recognition with prosthetic stimulation.
Adolescent↗
[Problems and possible solutions in evaluation of dichotic discrimination tests for children].
Uttenweiler's dichotic discrimination test is a valuable contribution to the diagnosis of auditory perception disorders. With this test it is possible to establish whether there is a deficit in a patient's ability to discriminate between differing spoken signals to each ear, as shown in a study contrasting elementary school age children with normal hearing with children having auditory perception disorders. Until now only a limited comparison of test results has been possible, as previous test modes have required an increase in volume when words could not be completely distinguished. A further problem is that very different hearing abilities may give rise to the same test configurations. This study presents an alternative test method that allows a direct individual comparison of results. The volume of the words spoken is no longer increased when words are not adequately understood. In addition, a point system is introduced that enables a quantitative analysis of the same test performances. This new evaluation scale is explained on the basis of actual examples.
Auditory Perceptual Disorders↗
Effects of phonetic context on audio-visual intelligibility of French.
Bimodal perception leads to better speech understanding than auditory perception alone. We evaluated the overall benefit of lip-reading on natural utterances of French produced by a single speaker. Eighteen French subjects with good audition and vision were administered a closed set identification test of VCVCV nonsense words consisting of three vowels [i, a, y] and six consonants [b, v, z, 3, R, l]. Stimuli were presented under both auditory and audio-visual conditions with white noise added at various signal-to-noise ratios. Identification scores were higher in the bimodal condition than in the auditory-alone condition, especially in situations where acoustic information was reduced. The auditory and audio-visual intelligibility of the three vowels [i, a, y] averaged over the six consonantal contexts was evaluated as well. Two different hierarchies of intelligibility were found. Auditorily, [a] was most intelligible, followed by [i] and then by [y]; whereas visually [y] was most intelligible, followed by [a] and [i]. We also quantified the contextual effects of the three vowels on the auditory and audio-visual intelligibility of the consonants. Both the auditory and the audio-visual intelligibility of surrounding consonants was highest in the [a] context, followed by the [i] context and lastly the [y] context.
Adult↗
Interference effects and phase sensitivity in hearing.
This paper reviews interference effects in the auditory system, particularly effects occurring in the outer ear and the inner ear (cochlea). Sounds enter the ear canal both directly and after reflections from the pinna. This results in complex spectral patterns, which vary systematically with the direction of incidence of the sound source relative to the head. Evidence is described indicating that these spectral patterns are used in the localization of sounds in space. The cochlea behaves like a limited-resolution frequency analyser. When the components of a complex sound are closely spaced in frequency, they can interfere on the basilar membrane (BM) within the cochlea. Interference effects on the BM are complex, as they are influenced by a physiologically active mechanism which introduces strong nonlinearities, including level-dependent amplification. Interference effects on the BM play a role in many aspects of auditory perception, including the perception of consonance and dissonance, the perception of pitch, the perception of changes in phase, and the perception of timbre. Interference effects in the cochlea may also play a role in producing the spectral regularity observed in sounds reflected from the ear (otoacoustic emissions).
Animals↗
The distinct contributions of age of acquisition and word frequency in auditory word perception.
We report two studies of the distinct effects that a word's age of acquisition (AoA) and frequency have on the mental lexicon. In the first study, a purely statistical analysis, we show that AoA and frequency are related in different ways to the phonological form and imageability of different words. In the second study, three groups of participants (34 seven-year-olds, 30 ten-year-olds, and 17 adults) took part in an auditory lexical decision task, with stimuli varying in AoA, frequency, length, neighbourhood density, and imageability. The principal result is that the influence of these different variables changes as a function of AoA: Neighbourhood density effects are apparent for early and late AoA words, but not for intermediate AoA, whereas imageability effects are apparent for intermediate AoA words but not for early or late AoA. These results are discussed from the perspective that AoA affects a word's representation, but frequency affects processing biases.
Adult↗