Monthly Archives: February 2009
The effect of experience on the perception and representation of dialect variants
Abstract
The task of recognizing spoken words is notoriously difficult. Once dialectal variation is considered, the difficulty of this task increases. When living in a new dialect region, however, processing difficulties associated with dialectal variation dissipate over time. Through a series of primed lexical decision tasks (form priming, semantic priming, and long-term repetition priming), we examine the general issue of dialectal variation in spoken word recognition, while investigating the role of experience in perception and representation. The main questions we address are: (1) how are cross-dialect variants recognized and stored, and (2) how are these variants accommodated by listeners with different levels of exposure to the dialect? Three claims are made based on the results: (1) dialect production is not always representative of dialect perception and representation, (2) experience strongly affects a listener’s ability to recognize and represent spoken words, and (3) there is a general benefit for variants that are not regionally-marked.
from the Journal of Memory and Language
Visualization of Reissner membrane and the spiral ganglion in human fetal cochlea by micro-computed tomography
Conclusions
This study showed that µ-CT enables us to visualize the internal fine structure of the human cochlea. As the success rate of the visualization of Reissner membrane is not high, it is necessary to improve the image quality and contrast resolution of µ-CT to enable stable visualization of fine structures. The development of imaging equipment such as µ-CT for medical use should play an important role in the elucidation of the mechanism and the establishment of therapy for inner ear diseases.
from the American Journal of Otolaryngology
Iatrogenic carotid artery pseudoaneurysm presenting with conductive hearing loss
Abstract
Pseudoaneurysms of the intracranial internal carotid artery may occur in the setting of carotid artery dehiscence, due to trauma, invasive tumors, or as a complication of surgery. The rare surgical complication of carotid artery laceration in the petrous segment may occur during myringotomy procedures, middle ear operations, or petrous temporal bone surgery. We report a 28-year-old female patient, a case of internal carotid artery pseudoaneurysm as a complication of middle ear surgery. On her follow-up, computed tomography of the temporal bone demonstrated a dehiscent carotid artery, and a pseudoaneurysm involving the left petrous internal carotid artery was found in the cerebral angiography. She was managed by endovascular means.
from the American Journal of Otolaryngology
Aphasic speech with and without SentenceShaper® : Two methods for assessing informativeness
Conclusions: That the percentage of CIUs was higher in SSR-aided samples than in unaided samples confirms the central finding in Bartlett et al. (2007), based on subjective judgements, and thus extends the evidence that aided effects from SentenceShaper are demonstrable across a range of measures, stimuli and participants (cf. Linebarger, Schwartz, Romania, Kohn, & Stephens, 2000). The data also attest to the effectiveness of the CIU analysis for quantifying differences in the informativeness of aphasic speech with and without SentenceShaper; and they support prior studies that have shown that CIU measures correlate with the informativeness ratings of unfamiliar listeners.
from Aphasiology
Effect of bimodal hearing in Korean children with profound hearing loss.
CONCLUSION: Bimodal hearing with combined acoustic stimulation and electric stimulation could enhance speech performance in deaf patients by residual hearing even though the amount of residual hearing is not enough to be used for communication by amplification. OBJECTIVES: The cochlear implant (CI) is a well-known therapeutic option for patients with profound hearing loss. However, deaf patients with a CI still have trouble in localization of sounds and understanding speech in a noisy environment. The aim of this study was to evaluate the benefits of bimodal hearing with a CI in one ear and a hearing aid in the contralateral ear in Korean children with profound hearing loss. SUBJECTS AND METHODS: Fourteen deaf children with residual hearing participated in this study. There were eight male and six female patients, with an age range of 4.6-13.8 years at the time of testing. The test was conducted between 3 months and 4.2 years after cochlear implantation. Speech performance was examined in a noisy environment using Korean word lists. A speech sound and the noise were presented to the child from the front loudspeaker. RESULTS: The results showed that speech performance in a noisy environment was significantly better with bimodal hearing than with a CI alone.
Bone-anchored hearing aid in unilateral inner ear deafness: electrophysiological results in patients following vestibular schwannoma removal.
CONCLUSIONS: The results show that the healthy cochlea perceives one auditory stimulus from two auditory signals: the first through normal air conduction and the second provided by the bone-anchored hearing aid (BAHA). This artificial acoustic difference could partly explain ‘pseudo’ binaural hearing. Functional cerebral imaging using the same experimental procedure is now necessary. OBJECTIVES: The aim of this study was to evaluate electrophysiological phenomena induced by BAHA on brainstem and long-latency auditory evoked potentials (AEPs) to understand how patients recover a ‘pseudo’ binaural sensation with only one functional cochlea. PATIENTS AND METHODS: This prospective study included 10 patients operated via the translabyrinthine approach and who received implants on the deaf side. Electrophysiological recordings were performed at least 2 months after BAHA use. Brainstem and long-latency (N1, P2, N2, P300) AEPs were studied in free field according to four conditions: 1, without BAHA; 2, with BAHA; 3, with BAHA and normal ear occluded; 4, without BAHA and normal ear occluded. RESULTS: For brainstem AEPs, we found significantly longer latencies of waves III and V in condition 3 compared with condition 1. For long-latency AEPs, comparison between conditions showed no significant differences.
A clinical study of microcirculatory disturbance in Chinese patients with sudden deafness
CONCLUSION: Cochlear microcirculation disturbance is closely associated with sudden deafness. OBJECTIVES: To investigate the relationship between cochlear microcirculation and sudden deafness. SUBJECTS AND METHODS: Clinical laboratory parameters (clinical chemistry, hemorheology, hematology, and hemostasis determinations) were studied in 86 patients with sudden deafness and 30 healthy control subjects. RESULTS: The levels of total cholesterol (TCH), triglyceride (TG), and lipoprotein A were significantly higher in patients with sudden deafness than in control subjects. Plasma viscosity, ratio viscosity of whole blood, reduced viscosity of whole blood, high and low shear relative viscosity of whole blood, index of red blood cells transmutation, and fibrinogen level in the plasma of patients with sudden sensorineural hearing loss (SSNHL) were also significantly elevated in comparison with those in control subjects. White-collar workers with psychological and behavioral abnormalities tend to suffer from sudden deafness.
How symbolic gestures and words interact with each other
Previous repetitive Transcranial Magnetic Stimulation and neuroimaging studies showed that Broca’s area is involved in the interaction between gestures and words. However, in these studies the nature of this interaction was not fully investigated; consequently, we addressed this issue in three behavioral experiments. When compared to the expression of one signal at a time, arm kinematics slowed down and voice parameters were amplified when congruent words plus gestures were simultaneously produced (experiment 1). When word and gesture were incongruent, arm kinematics did not change regardless of word category, whereas the gesture induced variation in vocal parameters of communicative and action words only (experiments 2 and 3). Data are discussed according to the hypothesis that integration between gesture and word occurs by transferring the social intention to interact directly with the interlocutor from the gesture to the word.
from Brain and Language
Objective Voice Analysis of Iranian Speakers with Normal Voices
Conclusions
The present study developed a body of normal data for various parameters of acoustic analysis in different age groups and genders of normal Iranian adults. It seems that the majority of voice characteristics of adults was relatively stable and did not change with aging between 20 and 50 years. However, the voice characteristics of adults older than 50 years were not recorded in this study and therefore require further investigation.
from the Journal of Voice
Emergence and progression of ‘non-semantic’ deficits in semantic dementia
Abstract
Although semantic dementia (SD) is defined as a selective disruption of conceptual knowledge, a number of group studies have now demonstrated that SD patients also show impaired performance on tasks not usually considered to have a high semantic load (e.g., reading words aloud and lexical or object decision). The aim of the current study was to document the relative deterioration, over time, of a number of semantic and so-called ‘non-semantic’ tasks in LF, a single case of SD for whom – by virtue of his work as a published cartoonist – we also have extensive data regarding his pre-morbid linguistic and drawing skills.
In five testing rounds over a period of five years we administered semantic tests of object naming and object definition (on both of which LF was progressively impaired, as expected for a diagnosis of SD), plus verbal and non-verbal ‘non-semantic’ tasks of reading aloud, spelling, object and lexical decision, and delayed copy drawing.
Initially, his only striking ‘non-semantic’ deficit was in the domain of spelling – a pronounced surface dysgraphia in an individual with demonstrably superior pre-morbid spelling skill. Over time, and in line with his declining semantic system, LF’s performance gradually deteriorated on all of the ‘non-semantic’ tasks. The most vulnerable items on most tasks were those with low frequency and an atypical form.
This report adds to the growing body of evidence that a number of cognitive processes not usually considered to be ‘semantic’ in their demands rely on the integrity of semantic knowledge for successful execution. Furthermore, it provides the first indication that these non-semantic deficits might emerge in an order predictable from the typicality structure of the relevant domain.
from Cortex
Patterns of autobiographical memory impairment according to disease severity in semantic dementia
Studies of autobiographical memory in semantic dementia (SD) have yielded either a reversed temporal gradient or spared performances across the entire lifetime. This discrepancy might be owing to the fact that these studies did not take into account disease severity. Our aim was to study patterns of autobiographical memory impairment according to disease severity and to unravel their mechanisms in 14 SD patients, using an autobiographical memory task assessing overall and strictly episodic memories across the entire lifetime. We divided our patients in 2 subgroups of 7 patients each, one mild and one moderate according to their level of disease severity. The results indicated for the mild subgroup selective preserved performances for the most recent time period (last 12 months period) for both autobiographical memory scores. In the moderate subgroup, performances were impaired for both scores whatever the time period. Within-group comparisons across time periods showed a recency effect and a reminiscence bump in the mild subgroup and only a less important recency effect in the moderate subgroup, suggesting that with disease severity, old memories (reminiscence bump) tend to vanish and even recent memories are less well retrieved. A correlation analysis was carried out on the entire group, between the overall autobiographical memory score and performances provided by a general cognitive evaluation (semantic memory, executive functions, working and episodic memory). The results of this analysis reflect that mechanisms of disruption of autobiographical memory in SD predominantly involve a deficit of storage of semantic information in addition to faulty executive retrieval strategies. Finally, our result and those of the literature suggest the existence of 3 distinct autobiographical memory impairment patterns in SD according to disease severity: firstly preserved performances whatever the time period, secondly a reversed temporal gradient with a reminiscence bump and thirdly the appearance of a “step-function”.
from Cortex
Re-evaluating split-fovea processing in word recognition: Effects of word length
Several studies have claimed that, when fixating a word, letters to the left and right of fixation project to different hemispheres and are consequently subjected to different processes. In support of this claim, Lavidor M, et al. (2001; hereafter LES&B) report that lexical decisions were affected by increasing the number of letters to the left of fixation but not to the right, and that this indicates divided hemispheric access at the point of fixation to length–sensitive processes in the right hemisphere (RH). We re-evaluated these claims in Experiment 1 using Lavidor et al.’s original stimuli and procedure of merely instructing participants where to fixate. In contrast to the earlier study, increases in the number of letters to the left and right of the designated fixation location produced near-identical effects on reaction time, and increases to the left actually improved response accuracy and increases to the right impaired it. When larger stimuli were used to improve stimulus perceptibility and an eye-tracker monitored fixation accuracy (Experiment 2), left and right increases in the number of letters again produced near-identical effects on reaction time (and accuracy), but frequent and substantial fixation errors were revealed. When an eye-tracker ensured accurate fixations (Experiment 3), left and right increases in the number of letters again produced near-identical effects on reaction time and accuracy. Thus, the findings of all three experiments provide no support for the findings of LES&B (2001) and no evidence of split-fovea processing. The findings also indicate the dangers of assuming fixation of precisely-specified locations within words, both in experiments designed to reveal split-foveal processing and hemispheric asymmetry and in more normal circumstances of word perception.
from Cortex
Supramarginal gyrus involvement in visual word recognition
Conclusion
These findings demonstrate that SMG contributes to reading regardless of the specific task demands, and suggests this may be due to automatically computing the sound of a word even when the task does not explicitly require it.
from Cortex
Vowel-specific mismatch responses in the anterior superior temporal gyrus: An fMRI study
There have been many functional imaging studies that have investigated the neural correlates of speech perception by contrasting neural responses to speech and “speech-like” but unintelligible control stimuli. A potential drawback of this approach is that intelligibility is necessarily conflated with a change in the acoustic parameters of the stimuli. The approach we have adopted is to take advantage of the mismatch response elicited by an oddball paradigm to probe neural responses in temporal lobe structures to a parametrically varied set of deviants in order to identify brain regions involved in vowel processing. Thirteen normal subjects were scanned using a functional magnetic resonance imaging (fMRI) paradigm while they listened to continuous trains of auditory stimuli. Three classes of stimuli were used: ‘vowel deviants’ and two classes of control stimuli: one acoustically similar (‘single formants’) and the other distant (tones). The acoustic differences between the standard and deviants in both the vowel and single-formant classes were designed to match each other closely. The results revealed an effect of vowel deviance in the left anterior superior temporal gyrus (aSTG). This was most significant when comparing all vowel deviants to standards, irrespective of their psychoacoustic or physical deviance. We also identified a correlation between perceptual discrimination and deviant-related activity in the dominant superior temporal sulcus (STS), although this effect was not stimulus specific. The responses to vowel deviants were in brain regions implicated in the processing of intelligible or meaningful speech, part of the so-called auditory “what” processing stream. Neural components of this pathway would be expected to respond to sudden, perhaps unexpected changes in speech signal that result in a change to narrative meaning.
from Cortex
Relationship Between Transglottal Pressure and Fundamental Frequency of Phonation—Study Using a Rubber Model
The relationship between the change in fundamental frequency of phonation (F0) per unit change of transglottal pressure (dF/dP) was studied using a rubber model of the vocal folds that allows the stiffness and elongation of the vibrating part to be varied flexibly. Changes in elongation and stiffness successfully reproduced the negative relationship between dF/dP and F0 at low F0 seen in humans. The thyroarytenoid muscle appears to work concomitantly with the cricothyroid (CT) muscle to regulate F0, raising F0 by increasing the stiffness of the vibrating part at low F0, that is, when the CT muscle is relaxed.
from the Journal of Voice
