Monthly Archives: September 2009
Comparison of vent effects between a solid earmold and a hollow earmold.
BACKGROUND: Hollow earmolds have become a popular type of earmold used in thin-tube, microsize hearing aid fittings. It is desirable for clinicians to be familiar with their characteristics and limitations. PURPOSE: This investigation compared the effects of vent diameter between a traditional solid earmold and a hollow earmold that is used in modern thin-tube hearing aid fittings. RESEARCH DESIGN: A single-blind, 2 x 4 factorial design was used. STUDY SAMPLE: Eight adults with a high-frequency hearing loss participated. INTERVENTION: Custom earmolds for use with thin-tube hearing aids were made for each participant. Two types of earmolds were made: a solid earmold with a traditional vent length and a hollow earmold where the thickness of the shell was the length of the vent. Vent diameters were 0, 1, 2, and 3 mm. DATA COLLECTION AND ANALYSIS: The vent effect was evaluated on real-ear aided response, real-ear occluded response during vocalization, subjective occlusion rating, insertion loss, and maximum available gain before feedback. Real-ear measurements were made with the Fonix 6500 probe-microphone real-ear system. Vocalizations from the participants were analyzed with a custom MATLAB program, and statistical analysis was conducted with SPSS software. RESULTS: A systematic vent effect was seen with each earmold type as the nominal vent diameter changed. For the same vent diameter, the vent effect seen with the hollow earmold was greater than that of the solid earmold. CONCLUSIONS: Because of the difference in vent length (and thus acoustic mass) between a solid and a hollow earmold, the effect of vent diameter in a hollow earmold is more pronounced than that seen in a solid earmold of the same nominal vent diameter. Thus, a smaller vent diameter will be needed in a hollow earmold than in a solid earmold to achieve similar vent effects.
Efficacy of linear frequency transposition on consonant identification in quiet and in noise.
BACKGROUND: Frequency transposition has gained renewed interest in recent years. This type of processing takes sounds in the unaidable high-frequency region and moves them to the lower frequency region. One concern is that the transposed sounds mask or distort the original low-frequency sounds and lead to a poorer performance. On the other hand, experience with transposition may allow the listeners to relearn the new auditory percepts and benefit from transposition. PURPOSE: The current study was designed to examine the effect of linear frequency transposition on consonant identification in quiet (50 dB SPL and 68 dB SPL) and in noise at three intervals–the initial fit, after one month of use (along with auditory training), and a further one month of use (without directed training) of transposition. RESEARCH DESIGN: A single-blind, factorial repeated-measures design was used to study the effect of test conditions (three) and hearing aid setting/time interval (four) on consonant identification. STUDY SAMPLE: Eight adults with a severe-to-profound high-frequency sensorineural hearing loss participated. INTERVENTION: Participants were fit with the Widex m4-m behind-the-ear hearing aids binaurally in the frequency transposition mode, and their speech scores were measured initially. They wore the hearing aids home for one month and were instructed to complete a self-paced “bottom-up” training regimen. They returned after the training, and their speech performance was measured. They wore the hearing aids home for another month, but they were not instructed to complete any auditory training. Their speech performance was again measured at the end of the two-month trial. DATA COLLECTION AND ANALYSIS: Consonant performance was measured with a nonsense syllable test (ORCA-NST) that was developed at this facility (Office of Research in Clinical Amplification [Widex]). The test conditions included testing in quiet at 50 dB SPL and 68 dB SPL, and at 68 dB SPL in noise (SNR [signal-to-noise ratio] = +5). The hearing aid conditions included no transposition at initial fit (V1), transposition at initial fit (V2), transposition at one month post-fit (V3), and transposition at 2 months post-fit (V4). Identification scores were analyzed for each individual phoneme and phonemic class. Repeated-measures ANOVA were conducted using SPSS software to examine significant differences. RESULTS: For all test conditions (50 dB SPL in quiet, 68 dB SPL in quiet, and 68 dB SPL in noise), a statistically significant difference (p < 0.05 level) was reached between the transposition condition measured at two months postfitting and the initial fitting (with and without transposition) for fricatives only.
Morphological changes in the middle latency response using maximum length sequence stimuli.
BACKGROUND: The middle latency response (MLR) can be a powerful tool for assessing integrity of cortical and subcortical auditory structures. Most research on the MLR, however, is constrained to relatively slow repetition rates by the time window necessary for response acquisition. Maximum length sequence (MLS) paradigms enable the recording of the MLR at high repetition rates, which could reduce test time and provide information about the behavior of auditory structures at rapid rates of stimulation. PURPOSES: To examine potential timing advantages and differences in waveforms between an MLS-MLR paradigm compared to a conventional MLR paradigm (Experiment 1), and to examine effects of rate on MLR morphology within the MLS paradigm (Experiment 2). RESEARCH DESIGN: A repeated measures study. All subjects within each experiment underwent every condition for that experiment. STUDY SAMPLE: Ten young adult female subjects participated in each experiment of this study. All subjects had normal hearing and negative neurological history. DATA COLLECTION AND ANALYSIS: Latency and amplitude values as well as the presence/absence of Na, Pa, Nb, and Pb components of the MLR were measured. Comparisons were made between the MLS-MLR and conventional MLR paradigms, as well as between repetition rates within the MLS-MLR paradigm. RESULTS: Significant latency and amplitude differences were found between MLS and conventional MLR paradigms. The late components of the MLR (Nb, Pb) were present significantly more often when the MLS paradigm was used. No timing advantage was found with the MLS-MLR paradigm. Within the MLS paradigm, as repetition rate increases, latency becomes significantly shorter and amplitude significantly lower. CONCLUSIONS: Middle latency responses evoked by the MLS-MLR paradigm show significant differences from those evoked by a conventional MLR paradigm. The MLS-MLR paradigm can reliably evoke the late components (Nb, Pb) of the MLR and may be an important clinical tool for future investigation of these elements.
Observations on hearing aid users’ strategies for controlling the level of their own voice.
BACKGROUND: Evidence suggests that hearing-aid users have difficulties with own-voice level control, most likely because their auditory feedback is affected by hearing-aid amplification. PURPOSE: The purpose of this study was to investigate how changes to auditory feedback affect the voice level of hearing-aid users. RESEARCH DESIGN: A correlational study was set up to investigate the relation between voice level and hearing-aid amplification. STUDY SAMPLE: Seven hearing-impaired speakers participated. All were experienced hearing-aid users. DATA COLLECTION AND ANALYSIS: The speakers projected their voice to a passive listener across different speaker-listener distances and with different prescriptions of gain in an experimental hearing aid. For each combination of conditions, produced voice level and self-perceived voice level was measured. These data were subjected to an analysis of variance assuming a mixture of random and fixed effects. In addition, all speakers took part in interviews. RESULTS: Three speakers reacted to the changes in auditory feedback in agreement with previous experiments with normal-hearing speakers: they compensated by changing produced voice level. In contrast, the voice levels in the other four speakers were largely unaffected by the changes to auditory feedback. A secondary observation was that while all speakers increased their voice level with distance, the two subgroups produced different growth rates of vocal level versus distance. CONCLUSIONS: It is hypothesized that the speakers in the former subgroup relied on auditory feedback for solving the experimental task, whereas the latter subgroup had developed an own-voice level-control strategy based on proprioceptory feedback, possibly because they have lost faith in their auditory feedback mechanism, which indeed is changed by both hearing loss and hearing-aid amplification. Comparison to “target” voice levels suggests that proprioceptory feedback is less effective than auditory feedback for achieving adequate level-distance growth rate.
NIDCD awards research grant to Mobius Therapeutics
Mobius Therapeutics, LLC ™ has been awarded a research grant from the National Institute on Deafness and other Communication Disorders (NIDCD) to study its investigational procedure, selective Photodynamic Myringotomy (PDM).
from News-Medical.net
Clinical practice guideline: hoarseness (dysphonia)
Aims: The primary purpose of this guideline is to improve the quality of care for patients with hoarseness based on current best evidence.
Specific objectives of the guideline are to reduce inappropriate variations in care, produce optimal health outcomes, and minimize harm.
from the National Library for Health
Attention Makes Sensory Signals Stand Out Amidst The Background Noise In The Brain
Researchers at the Salk Institute for Biological Studies studying visual attention have discovered a novel mechanism that explains how incoming sensory signals make themselves heard amidst the constant background rumblings so they can be reliably processed and passed on.
New ‘Direct Referral’ Criteria Launched
The BAA ‘Direct Referral Criteria’ replaces the ‘Technicians, Therapists and Scientists Association’ document (TTSA, 1989). This update now encompasses current audiology practice.
from the British Academy of Audiology
Vestibular evoked myogenic potential (VEMP) testing: normative threshold response curves and effects of age.
CONCLUSION: We have demonstrated that minor differences in VEMP responses occur with age. Given the reduced response rates and flattened frequency tuning curve for individuals over the age of 60, frequency tuning curves may not be a good diagnostic indicator for this age group.
Assessing the impact of FOXP1 mutations on developmental verbal dyspraxia
Neurodevelopmental disorders that disturb speech and language are highly heritable. Isolation of the underlying genetic risk factors has been hampered by complexity of the phenotype and potentially large number of contributing genes. One exception is the identification of rare heterozygous mutations of the FOXP2 gene in a monogenic syndrome characterised by impaired sequencing of articulatory gestures, disrupting speech (developmental verbal dyspraxia, DVD), as well as multiple deficits in expressive and receptive language. The protein encoded by FOXP2 belongs to a divergent subgroup of forkhead-box transcription factors, with a distinctive DNA-binding domain and motifs that mediate hetero- and homodimerisation. FOXP1, the most closely related member of this subgroup, can directly interact with FOXP2 and is co-expressed in neural structures relevant to speech and language disorders.
Effects of therapy in oropharyngeal dysphagia by speech and language therapists: a systematic review
Bottom-line conclusion: Many questions remain about the effects of therapy in oropharyngeal dysphagia as performed by speech and language therapists. Although some positive significant outcome studies have been published, further research based on randomized controlled trials is needed.
from the National Library for Health
Distortion of auditory space in hemianopia
Sound localization was investigated in patients with homonymous hemianopia, a visual field defect characterized by a loss of vision in one hemifield that is caused by unilateral brain lesions involving the visual cortex or its afferents. The primary aim was to clarify whether or not the known distortion of visual space in hemianopia results in processes of long-term cross-modal spatial adaptation, thus eventually inducing related alterations in auditory space perception. For this purpose, patients were tested by using tasks of either head pointing or manual pointing to acoustic targets in the azimuthal plane, under anechoic conditions in total darkness. The results obtained with both tasks consistently indicated slight, but significant, systematic errors compared with normal controls. In particular, the errors found can be interpreted by both rotation and compression of auditory space toward the anopic side. These findings can be explained by a visual miscalibration of the auditory space, as has been analogously demonstrated in studies on normal-sighted subjects after exposure to consistent auditory–visual disparity, for example by wearing prism lenses. The precision in sound localization of hemianopic patients was generally reduced across both hemispaces. Taken together, one may conclude that processes of cross-modal spatial adaptation, but not those of compensatory plasticity, occurred in patients with hemianopia.
from the European Journal of Neuroscience
Imaging short- and long-term training success in chronic aphasia
Conclusions
The results show for the first time that treatment-induced language recovery in the chronic stage after stroke is a dynamic process. Initially, brain regions involved in memory encoding, attention, and multimodal integration mediated treatment success. In contrast, long-term treatment success was predicted mainly by activity increases in the so-called ‘classical’ language regions. The results suggest that besides perilesional and homologue language-associated regions, functional integrity of domain-unspecific memory structures may be a prerequisite for successful (intensive) language interventions.
from BMC Neuroscience
Tympanosclerosis and our surgical results
Tympanosclerosis is a sequel of chronic otitis media characterized by the deposition of calcareous plaques following hyaline degeneration in the fibrous layer of the tympanic membrane and inside middle ear mucosa. It usually results from prior middle ear infections. In this study, results of treatment and clinical findings of the patients with tympanosclerosis are presented. Our objective is to determine the changes in middle ear caused by tympanosclerosis and intervene in the more problematic zone and find out the more useful treatment protocol for patients. Preoperative features, middle ear findings detected during surgery and postoperative hearing levels of the patients who were operated in our clinic between January 1996 and June 2006 due to tympanosclerosis were evaluated. Surgical treatment was performed on a total of 37 patients including 25 females and 12 males between ages of 11 and 71. Preoperative tympanic membranes perforations were presented at a rate of 91% and average airway bone gap was 37.8 dB. Bilateral involvement was present in 59%. Conductive-type hearing loss was present at a rate of 81%, whereas mixed-type hearing existed at a rate of 19%. Sclerotic plaques were most commonly localized in the attic with a rate of 72%. Post-op outcome was found to be 27% in the patients with air bone gap between 0–20 dB. The best hearing result belonged to type 1 patients. Cases in which stapes footplate was fixated had the worst result in terms of hearing. Teflon piston was only applied in one patient. Our tympanoplasty success was found to be 67%. The most common treatment method of tympanosclerosis is surgery. Stapedectomy is recommended in surgery instead of mobilization techniques. However, there is often recurrence and there is no curative treatment. Therefore rehabilitation with hearing device can be preferred as an adjunct. In the recent experimental studies, good results with topical or systemic agents have also been promising.
from ORL -Journal for Oto-Rhino-Laryngology and Its Related Specialties
