5,217 research outputs found
Filtering to match hearing aid insertion gain to individual ear acoustics
No full textWhen hearing aid gain is prescribed by software, gain is calculated based on the average acoustics for the age of patient, gender, mold type, and so on. The acoustics of the individual’s ear often vary from the average values, so there will be a mismatch between the prescribed gain and the real-ear gain. Real-ear measurement can be used to verify the gain and adjust it to meet targets, but the quality of the match will be limited by the number of channels and the flexibility of the hearing aid. A potential way to improve this process is to generate a filter that compensates for variations in real-ear insertion gain due to individual ear acoustics. Such a filter could be included in the processing path of a digital hearing aid. This article describes how such a filter can be generated using the windowing method, and the principle is demonstrated in a real ear. The approach requires communication between the real-ear measurement and hearing aid programming software. A finite impulse response filter with group delay just over 2 ms matched insertion gain to target values within the acceptable tolerance defined by British Society of Audiology guideline
Letter From William Bell Scott to Mr Chambers
No full textabstract: Concerning Scott's thanks, his writings about his own works, and a manuscript of "The Nightingale Unheard."Seller's Description: Reads "A.L.S. from Author to Mr. Chambers explaining how busy he is... The sonnet is printed in the book. Fredeman: 56.7 £87.50"Handwritten Note: Unknown handwriting at top right reads "June 1st 1877."Publication Details: "The Nightingale Unheard" published in "Poems" by William Bell Scott.Creation Date Details: Undated range is the author's lifespan.Provenance: Removed from:
Poems / by William Bell Scott. Ballads, studies from nature, sonnets, etc. / illustrated by seventeen etchings by the author and L. Alma Tadema. Publisher London : Longmans, Green, 1875. CALL #
HAYDEN SPECIAL COLL SPEC PRB-13
Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes
No full textMelanie L Bell,1 Amy L Whitehead,2 Steven A Julious2 1Department of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson, AZ, USA; 2Medical Statistics Group, Design, Trials and Statistics, School of Health and Related Research (ScHARR), University of Sheffield, Sheffield, UK Background: A pilot study can be an important step in the assessment of an intervention by providing information to design the future definitive trial. Pilot studies can be used to estimate the recruitment and retention rates and population variance and to provide preliminary evidence of efficacy potential. However, estimation is poor because pilot studies are small, so sensitivity analyses for the main trial’s sample size calculations should be undertaken.Methods: We demonstrate how to carry out easy-to-perform sensitivity analysis for designing trials based on pilot data using an example. Furthermore, we introduce rules of thumb for the size of the pilot study so that the overall sample size, for both pilot and main trials, is minimized.Results: The example illustrates how sample size estimates for the main trial can alter dramatically by plausibly varying assumptions. Required sample size for 90% power varied from 392 to 692 depending on assumptions. Some scenarios were not feasible based on the pilot study recruitment and retention rates.Conclusion: Pilot studies can be used to help design the main trial, but caution should be exercised. We recommend the use of sensitivity analyses to assess the robustness of the design assumptions for a main trial. Keywords: pilot, feasibility, sample size, power, randomized controlled trial, sensitivity analysi
Data for Envelope Frequency Following Responses to Filtered Word Stimuli
No full textRaw EEG data in .bdf format, collected using a 32-channel ActiveTwo EEG system (BioSemi, the Netherlands). EEG data were measured during presentation of words at an intensity of 70 dB SPL LA eq using ER-2 insert earphones. Words are filtered in different band (0-500 Hz, 0-1000 Hz, 1000-end Hz and 2000-end Hz), with end being 8000 Hz as words were recorded at a sampling rate of 16000 Hz. Stimuli were 3 words presented randomly with an inter-stimulus interval of 1s. Data are published in according with the EPSRC guidelines for data sharing.
Data Supports the paper Vanheusden, F. J., Chesnaye, M. A., Simpson, D. M., & Bell, S. L. (2019). Envelope frequency following responses are stronger for high-pass than low-pass filtered vowels. International Journal of Audiology, 1-9. DOI: 10.1080/14992027.2018.1562243
This dataset, approx 28GB, is available on request via the webform at https://library.soton.ac.uk/datarequest</span
Vestibular evoked myogenic responses to amplitude modulated sounds
No full textAuditory Steady State Responses ASSR allow objective assessment of hearing thresholds. At high stimulation levels artifactual responses have been reported in subjects with severe to profound deafness. Relatively large amplitude ‘steady state’ responses to amplitude modulated tones were measured from the Sternocleidomastoid muscle at 500 Hz. Response thresholds were similar to those of Vestibular Evoked Myogenic Potentials and scaled with neck muscle tension. ‘Steady-state’ myogenic responses showed broad tuning to modulation frequency. Reduced amplitude responses were measured at the inion indicating volume conduction from the SCM. While dependant on neck tension, such responses are a potential source of artifacts when recording ASSR
Optimizing the acquisition time of the middle latency response using maximum length sequences and chirps
No full textThe middle latency response (MLR) may be used as an indicator of anesthetic depth but has been criticized due to its long acquisition time. This study explores methods for optimizing recording of the MLR to maximize signal-to-noise ratio (SNR) and hence reduce acquisition time. The first experiment investigates the effects of increasing stimulation rate beyond conventional values and also using higher rates by means of maximum length sequences (MLS). The second experiment compares the use of click and chirp stimuli to elicit the MLR, both at conventional and MLS stimulation rates. For all conditions total recording duration is fixed at 185 s and stimulation level is fixed at 60 dB SL. It was found that SNR increases progressively with rate using conventional click stimulation until the theoretical rate limit is reached at the reciprocal of the response duration. The SNR improvement is equivalent to increasing test speed by a factor of 3. Using MLS stimulation, the SNR increases further until a maximum is reached at a rate of 167 clicks/s, equivalent to a fivefold test speed improvement relative to a conventional recording at 5 clicks/s. The use of chirp stimuli designed to compensate for the frequency dependent cochlear traveling wave delay produces an increase in wave V-Na amplitude at all recording rates. For the later latency waves of the response an increase in amplitude is seen for MLS, but not for conventional chirp trains. The optimum SNR was obtained using chirp stimuli at a MLS rate of 167 opportunities/s. It is concluded that the combination of chirps and MLS can reduce acquisition time to less than one-tenth of that required for conventional stimulation at 5 clicks/s for the same SNR. This would confer material benefits for estimating anesthetic depth using MLR
Measuring real-ear signal-to-noise ratio: application to directional hearing aids
No full textDue to individual characteristics such as head size, earmould type, and earmould venting, the directional benefit that an individual will obtain from a hearing aid cannot be predicted from average data. It is therefore desirable to measure real ear directional benefit. This paper demonstrates a method to measure real ear hearing aid directivity based on a general approach to measure the broadband output signal-to-noise ratio of a hearing aid. Errors arising from non-linearity were tested in simulation and found to be low for typical hearing aid compression ratios. Next, the efficacy of the method to estimate directional benefit was demonstrated on KEMAR. Finally the variability of directional benefit was explored in real-ears. Significant differences in signal-to-noise ratio between directional and omnidirectional microphone settings were demonstrated at most azimuths. Articulation-Index-weighted directional benefit varied by more than 7 dB across ears at some azimuths. Such individual variation in directional benefit has implications when fitting hearing aids: it should not be assumed that all users will receive similar directional benefit from the same hearing aid
Ocular vestibular evoked myogenic potentials elicited with vibration applied to the teeth
No full textObjectives: This study investigated whether the method for eliciting vibration-induced oVEMPs could be improved by applying vibration directly to the teeth, and how vibration-induced oVEMP responses depend on the duration of the applied vibration.Methods: In 10 participants, a hand-held shaker was used to present 100-Hz vibration tone pips to the teeth via a customised bite-bar or to other parts of the head. oVEMP potentials were recorded in response to vibration in three orthogonal directions and five stimulus durations (10–180 ms). The oVEMP responses were analysed in terms of the peak latency onset, peak-to-peak amplitude, and the quality of the trace.Results: Vibration applied to the teeth via the bite-bar produced oVEMPs that were more consistent, of higher quality and of greater amplitude than those evoked by vibration applied to the head. Longer duration stimuli produced longer duration oVEMP responses. One cycle duration stimuli produced responses that were smaller in amplitude and lower quality than the longer stimulus durations.Conclusions: Application of vibration via the teeth using a bite-bar is an effective means of producing oVEMPs. A 1-cycle stimulus is not optimal to evoke an oVEMP because it produces less robust responses than those of longer stimulus duration. A positive relationship between the duration of the stimulus and the response is consistent with the notion that the vibration-induced oVEMP is an oscillatory response to the motion of the head, rather than being a simple reflex response that occurs when the stimulus exceeds a threshold level of stimulation.Significance Applying acceleration to the teeth through a bite-bar elicits clearer oVEMP responses than direct application to other parts of the head and has potential to improve clinical measurements. A 100-Hz 1-cycle stimulus produces less robust oVEMP responses than longer 100-Hz stimul
Vestibular evoked myogenic potential (VEMP) test-retest reliability in adults
No full textBackground: the technique of measuring ocular vestibular evoked myogenic potentials (oVEMP) in response to Mini-shaker vibration is relatively new, there is a limited normative data to define the presence or absence of a response in the literature.Objective: to determine the test-retest reliability of cervical and ocular VEMPs (cVEMP and oVEMP, respectively) to air-conducted sound (ACS) and bone-conducted vibration (BCV) stimulation and to determine normative ranges for the responses.Methods: twenty normal-hearing individuals (40 ears) and 20 hearing impaired volunteers with normal balance function (40 ears) were examined in this study. ACS cVEMP and BCV oVEMP (using a Mini-shaker) were recorded from both groups to assess the test-retest reliability and to collect normative VEMP data for P1/N1 latencies and amplitudes from 20 normal hearing individuals. To test reliability, VEMP recordings were repeated within the same session. RESULTS: The test-retest reliability for all the cVEMP parameters showed excellent reliability whereas oVEMP parameters showed between fair and excellent reliability depending on the parameter tested. Normative data for VEMP P1/N1 latencies and amplitudes were established.Conclusions: normative data and test-retest reliability for BCV oVEMP using the Mini-shaker at 100 Hz were established in our study for the first time in the literature. Responses appear reliable. <br/
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