Monthly Archives: August 2010
Long-term results with the Rion E-type semi-implantable hearing aid
For long-term success in implantation of the IHA, careful control of middle ear inflammation and measures against eustachian tube dysfunction are required in addition to technological advancements.
Norms for pronunciation in Southeast Asia
Some pronunciation features that are not found in Inner Circle varieties of English are shared by the Englishes of Singapore, the rest of ASEAN, and China, and in some cases they serve to distinguish pairs of words which are no longer differentiated by many speakers in Britain. As these features of pronunciation do not interfere with comprehension and in some cases they actually enhance intelligibility, they can be promoted as part of the standard English that is emerging in Southeast Asia. However, there is likely to be less agreement about some other features, as for example, it may be argued that the relative absence of reduced vowels and the use of syllable-based rhythm do have an impact on intelligibility, so whether these features are encouraged as part of the regional standard English will remain more controversial. In addition to considering these features, this paper discusses the status of final consonants that are commonly deleted in British and American English, specifically whether the regular omission of these sounds by speakers in Southeast Asia should be encouraged.
from World Englishes
False Recollection of Emotional Pictures in Alzheimer’s Disease
Alzheimer’s Disease (AD) can reduce the effects of emotional content on memory for studied pictures, but less is known about false memory. In healthy adults, emotionally arousing pictures can be more susceptible to false memory effects than neutral pictures, potentially because emotional pictures share conceptual similarities that cause memory confusions. We investigatedthese effects in AD patients and healthy controls. Participants studied pictures and their verbal labels, and then picture recollection was tested using verbal labels as retrieval cues. Some of the test labels had been associated with a picture at study, whereas other had not. On this picture recollection test, we found that both AD patients and controlsincorrectly endorsed some of the test labels that had not been studiedwith pictures. These errors were associated with medium to high levels of confidence, indicating some degree of false recollection. Critically, these false recollection judgments were greater for emotionalcompared to neutral items, especially for positively valenced items, in both AD patients and controls. Dysfunction of the amygdala and hippocampusin early AD may impairrecollection, but ADdid not disrupt the effect of emotion on false recollection judgments.
from Neuropsychology
Perceptual Compensation Is Correlated with Individuals’ “Autistic” Traits: Implications for Models of Sound Change
Variation is a ubiquitous feature of speech. Listeners must take into account context-induced variation to recover the interlocutor’s intended message. When listeners fail to normalize for context-induced variation properly, deviant percepts become seeds for new perceptual and production norms. In question is how deviant percepts accumulate in a systematic fashion to give rise to sound change (i.e., new pronunciation norms) within a given speech community. The present study investigated subjects’ classification of /s/ and // before /a/ or /u/ spoken by a male or a female voice. Building on modern cognitive theories of autism-spectrum condition, which see variation in autism-spectrum condition in terms of individual differences in cognitive processing style, we established a significant correlation between individuals’ normalization for phonetic context (i.e., whether the following vowel is /a/ or /u/) and talker voice variation (i.e., whether the talker is male or female) in speech and their “autistic” traits, as measured by the Autism Spectrum Quotient (AQ). In particular, our mixed-effect logistic regression models show that women with low AQ (i.e., the least “autistic”) do not normalize for phonetic coarticulation as much as men and high AQ women. This study provides first direct evidence that variability in human’s ability to compensate for context-induced variations in speech perceptually is governed by the individual’s sex and cognitive processing style. These findings lend support to the hypothesis that the systematic infusion of new linguistic variants (i.e., the deviant percepts) originate from a sub-segment of the speech community that consistently under-compensates for contextual variation in speech.
from PLoS ONE
Autism research finds empirical link between multisensory integration and autism
August 19, 2010 — (BRONX, NY) — A new study by researchers at Albert Einstein College of Medicine of Yeshiva University has provided concrete evidence that children with autism spectrum disorders (ASD) process sensory information such as sound, touch and vision differently than typically developing children.
from EurekAlert.org
Cued Speech for Enhancing Speech Perception and First Language Development of Children With Cochlear Implants
Nearly 300 million people worldwide have moderate to profound hearing loss. Hearing impairment, if not adequately managed, has strong socioeconomic and affective impact on individuals. Cochlear implants have become the most effective vehicle for helping profoundly deaf children and adults to understand spoken language, to be sensitive to environmental sounds, and, to some extent, to listen to music. The auditory information delivered by the cochlear implant remains non-optimal for speech perception because it delivers a spectrally degraded signal and lacks some of the fine temporal acoustic structure. In this article, we discuss research revealing the multimodal nature of speech perception in normally-hearing individuals, with important inter-subject variability in the weighting of auditory or visual information. We also discuss how audio-visual training, via Cued Speech, can improve speech perception in cochlear implantees, particularly in noisy contexts. Cued Speech is a system that makes use of visual information from speechreading combined with hand shapes positioned in different places around the face in order to deliver completely unambiguous information about the syllables and the phonemes of spoken language. We support our view that exposure to Cued Speech before or after the implantation could be important in the aural rehabilitation process of cochlear implantees. We describe five lines of research that are converging to support the view that Cued Speech can enhance speech perception in individuals with cochlear implants.
Designing of a Digital Behind-the-Ear Hearing Aid to Meet the World Health Organization Requirements
Hearing loss is a common health issue that affects nearly 10% of the world population as indicated by many international studies. The hearing impaired typically experience more frustration, anxiety, irritability, depression, and disorientation than those with normal hearing levels. The standard rehabilitation tool for hearing impairment is an electronic hearing aid whose main components are transducers (microphone and receiver) and a digital signal processor. These electronic components are manufactured by supply chain rather than by hearing aid manufacturers. Manufacturers can use custom-designed components or generic off-the-shelf components. These electronic components are available as application-specific or off-the-shelf products, with the former designed for a specific manufacturer and the latter for a generic approach. The choice of custom or generic components will affect the product specifications, pricing, manufacturing, life cycle, and marketing strategies of the product. The World Health Organization is interested in making available to developing countries hearing aids that are inexpensive to purchase and maintain. The hearing aid presented in this article was developed with these specifications in mind together with additional contemporary features such as four channels with wide dynamic range compression, an adjustable compression rate for each channel, four comfort programs, an adaptive feedback manager, and full volume control. This digital hearing aid is fitted using a personal computer with minimal hardware requirements in intuitive three-step fitting software. A trimmer-adjusted version can be developed where human and material resources are scarce.
Objective Neural Indices of Speech-in-Noise Perception
Numerous factors contribute to understanding speech in noisy listening environments. There is a clinical need for objective biological assessment of auditory factors that contribute to the ability to hear speech in noise, factors that are free from the demands of attention and memory. Subcortical processing of complex sounds such as speech (auditory brainstem responses to speech and other complex stimuli [cABRs]) reflects the integrity of auditory function. Because cABRs physically resemble the evoking acoustic stimulus, they can provide objective indices of the neural transcription of specific acoustic elements (e.g., temporal, spectral) important for hearing speech. As with brainstem responses to clicks and tones, cABRs are clinically viable in individual subjects. Subcortical transcription of complex sounds is also clinically viable because of its known experience-dependence and role in auditory learning. Together with other clinical measures, cABRs can inform the underlying biological nature of listening and language disorders, inform treatment strategies, and provide an objective index of therapeutic outcomes. In this article, the authors review recent studies demonstrating the role of subcortical speech encoding in successful speech-in-noise perception.
Probing the Electrode-Neuron Interface With Focused Cochlear Implant Stimulation
Cochlear implants are highly successful neural prostheses for persons with severe or profound hearing loss who gain little benefit from hearing aid amplification. Although implants are capable of providing important spectral and temporal cues for speech perception, performance on speech tests is variable across listeners. Psychophysical measures obtained from individual implant subjects can also be highly variable across implant channels. This review discusses evidence that such variability reflects deviations in the electrode—neuron interface, which refers to an implant channel’s ability to effectively stimulate the auditory nerve. It is proposed that focused electrical stimulation is ideally suited to assess channel-to-channel irregularities in the electrode—neuron interface. In implant listeners, it is demonstrated that channels with relatively high thresholds, as measured with the tripolar configuration, exhibit broader psychophysical tuning curves and smaller dynamic ranges than channels with relatively low thresholds. Broader tuning implies that frequency-specific information intended for one population of neurons in the cochlea may activate more distant neurons, and a compressed dynamic range could make it more difficult to resolve intensity-based information, particularly in the presence of competing noise. Degradation of both types of cues would negatively affect speech perception.
Standard Audiograms for the IEC 60118-15 Measurement Procedure
For the characterization of hearing aids, a new test method has been defined in the new International Electrotechnical Commission (IEC) standard 60118-15. For this characterization, the hearing aid will be set to actual user settings as programmed by standard fitting software from the hearing aid manufacturer. To limit the variation of programming outcomes, 10 standard audiograms, which cover the entire range of audiograms met in clinical practice, have been defined. This article describes how the set of standard audiograms has been developed. This set of standard audiogram has been derived by a vector quantization analysis method on a database of 28,244 audiograms. Using this analysis method, sets of typical audiograms have been obtained of sizes 12 and 60. It turned out that the smaller set could not be used for selecting audiograms as sloping audiograms were absent. Therefore, the larger set has been analyzed to provide seven standard audiograms for flat and moderately sloping hearing loss and three standard audiograms for steep hearing loss.
Impaired Speech Repetition and Left Parietal Lobe Damage
Patients with left hemisphere damage and concomitant aphasia usually have difficulty repeating others’ speech. Although impaired speech repetition, the primary symptom of conduction aphasia, has been associated with involvement of the left arcuate fasciculus, its specific lesion correlate remains elusive. This research examined speech repetition among 45 stroke patients who underwent aphasia testing and MRI examination. Based on lesion–behavior mapping, the primary structural damage most closely associated with impaired speech repetition was found in the posterior portion of the left arcuate fasciculus. However, perfusion-weighted MRI revealed that tissue dysfunction, in the form of either frank damage or hypoperfusion, to the left inferior parietal lobe, rather than the underlying white matter, was associated with impaired speech repetition. This latter result suggests that integrity of the left inferior parietal lobe is important for speech repetition and, as importantly, highlights the importance of examining cerebral perfusion for the purpose of lesion–behavior mapping in acute stroke.
from the Journal of Neuroscience
Longitudinal Evidence for Functional Specialization of the Neural Circuit Supporting Working Memory in the Human Brain
Although children perform more poorly than adults on many cognitive measures, they are better able to learn things such as language and music. These differences could result from the delayed specialization of neural circuits and asynchronies in the maturation of neural substrates required for learning. Working memory—the ability to hold information in mind that is no longer present in the environment—comprises a set of cognitive processes required for many, if not all, forms of learning. A critical neural substrate for working memory (the prefrontal cortex) continues to mature through early adulthood. What are the functional consequences of this late maturation for working memory? Using a longitudinal design, we show that although individuals recruit prefrontal cortex as expected during both early and late adolescence during a working memory task, this recruitment is correlated with behavior only in late adolescence. The hippocampus is also recruited, but only during early, and not late, adolescence. Moreover, the hippocampus and prefrontal cortex are coactive in early adolescence regardless of task demands or performance, in contrast to the pattern seen in late adolescents and adults, when these regions are coactive only under high task demands. Together, these data demonstrate that neural circuitry underlying working memory changes during adolescent development. The diminishing contribution of the hippocampus in working memory function with age is an important observation that informs questions about how children and adults learn differently.
from the Journal of Neuroscience
Effect of auditory training on the middle latency response in children with (central) auditory processing disorder
The purpose of this study was to determine the middle latency response (MLR) characteristics (latency and amplitude) in children with (central) auditory processing disorder [(C)APD], categorized as such by their performance on the central auditory test battery, and the effects of these characteristics after auditory training. Thirty children with (C)APD, 8 to 14 years of age, were tested using the MLR-evoked potential. This group was then enrolled in an 8-week auditory training program and then retested at the completion of the program. A control group of 22 children without (C)APD, composed of relatives and acquaintances of those involved in the research, underwent the same testing at equal time intervals, but were not enrolled in the auditory training program. Before auditory training, MLR results for the (C)APD group exhibited lower C3-A1 and C3-A2 wave amplitudes in comparison to the control group [C3-A1, 0.84 µV (mean), 0.39 (SD - standard deviation) for the (C)APD group and 1.18 µV (mean), 0.65 (SD) for the control group; C3-A2, 0.69 µV (mean), 0.31 (SD) for the (C)APD group and 1.00 µV (mean), 0.46 (SD) for the control group]. After training, the MLR C3-A1 [1.59 µV (mean), 0.82 (SD)] and C3-A2 [1.24 µV (mean), 0.73 (SD)] wave amplitudes of the (C)APD group significantly increased, so that there was no longer a significant difference in MLR amplitude between (C)APD and control groups. These findings suggest progress in the use of electrophysiological measurements for the diagnosis and treatment of (C)APD.
The temporal relation between beat gestures and accompanying speech is examined in two experiments. In the first, we find that subjects are very quick to spot altered timing between gesture and speech if the gesture is later than normal, but are considerably less sensitive to alterations that result in an earlier gesture. This suggests an asymmetry in the expectation on the part of listeners/watchers and raises immediate questions about which elements within the speech are being perceived as linked to which elements in the gestural series. We therefore examine the variability between several kinematic landmarks in a beat gesture, and three potential anchor points in the accompanying speech. We find the least variable relationship obtains between the point of maximum extension of the gesture and the accompanying pitch accent. Together, these findings contribute to our understanding of both the production and perception of beat gestures along with speech, and support an account of speech communication as a strongly embodied activity.
The temporal relation between beat gestures and accompanying speech is examined in two experiments. In the first, we find that subjects are very quick to spot altered timing between gesture and speech if the gesture is later than normal, but are considerably less sensitive to alterations that result in an earlier gesture. This suggests an asymmetry in the expectation on the part of listeners/watchers and raises immediate questions about which elements within the speech are being perceived as linked to which elements in the gestural series. We therefore examine the variability between several kinematic landmarks in a beat gesture, and three potential anchor points in the accompanying speech. We find the least variable relationship obtains between the point of maximum extension of the gesture and the accompanying pitch accent. Together, these findings contribute to our understanding of both the production and perception of beat gestures along with speech, and support an account of speech communication as a strongly embodied activity.
