Biomedical subjects

Claus Elberling

Publications and source records attributed to Claus Elberling.

6 recordsLinked to original sources

PubMed2006

Linear and nonlinear hearing aid fittings--2. Patterns of candidature.

We studied candidature for linear, slow-acting AVC hearing aids, and fast-acting WDRC hearing aids in a within-subject within-device crossover design of 50 listeners with SNHL. Candidature dimensions include HTLs, ULLs, spectro-temporal and masking abnormalities, cognitive capacity, and self-reports and acoustic measures of auditory ecology. Better performance with linear fittings is associated with flatter audiograms, wider dynamic range, and smaller differences in dynamic range between low and high frequencies, and also with more restricted auditory lifestyles. Better performance with all nonlinear fittings is associated with more sloping audiograms, more restricted dynamic ranges, greater differences in dynamic range between low and high frequencies, and more varied auditory lifestyles. Differential performance between WDRC and AVC fittings is associated with patterns of variation in auditory ecology (rapid versus slow changes) and cognitive (high versus low) capacity. Differential performance between WDRC in two channels, and a hybrid with WDRC in a low-frequency and AVC in a high-frequency channel is associated with psychoacoustic tests of cochlear function (high susceptibility to spectral and temporal smearing, and high susceptibility to upward spread of masking respectively). Patterns of candidature include measures beyond auditory function in the domains of cognitive capacity and auditory ecology.

Aged↗

PubMed2006

Linear and nonlinear hearing aid fittings--1. Patterns of benefit.

We evaluated the benefits of fast-acting WDRC, slow-acting AVC, and linear reference fittings for speech intelligibility and reported disability, in a within-subject within-device masked crossover design on 50 listeners with SNHL. Five hearing aid fittings were implemented having two compression channels and seven frequency bands. Each listener sequentially experienced each fitting for a 10-week period. Outcome measures included speech intelligibility under diverse conditions and self-reported disability. At a group level, each nonlinear fitting was superior to the linear references for benefits in listening comfort, listener satisfaction, reported intelligibility and speech intelligibility. Slow-acting AVC outperformed the fast-acting WDRC fittings for listening comfort, while for reported and measured speech intelligibility the converse was true. For listener satisfaction there were no group differences between the nonlinear fittings. Analysis in terms of fittings for individual listeners revealed subsets with definite divergences from the group data and hence a need for candidature criteria. There are systematic differences between the benefits of nonlinear and linear fittings, and also within nonlinear fittings with fast versus slow time constants. The patterns of benefit and individual optima depend on the domain of outcome being assessed.

Aged↗

PubMed2006

Objective detection of auditory steady-state responses: comparison of one-sample and q-sample tests.

Auditory steady-state responses (ASSR) are expected to be useful for the objective, frequency-specific assessment of hearing thresholds in small children. To detect ASSR close to the hearing threshold, a powerful statistical test has to be applied. At present, so-called one-sample tests are used. These tests only evaluate the phase, or the phase and amplitude, of the first harmonic, that is, the fundamental frequency. It is shown that higher harmonics with significant amplitudes are also contained in the ASSR spectrum. For this reason, statistical tests that only consider the first harmonic ignore a significant portion of the available information. The use of a q-sample test, which, in addition to the fundamental frequency, also includes higher harmonics in the detection leads to a better detection performance. The evaluation of test performance uses both detection rate and detection time.

Acoustic Stimulation↗

PubMed2006

New efficient stimuli for evoking frequency-specific auditory steady-state responses.

ASSR is a promising tool for the objective frequency-specific assessment of hearing thresholds in children. The stimulus generally used for ASSR recording (single amplitude-modulated carrier) only activates a small area on the basilar membrane. Therefore, the response amplitude is low. A stimulus with a broader frequency spectrum can be composed by adding several cosines whose frequency intervals comply with the desired stimulus repetition rate. Compensation of the travelling wave delay on the basilar membrane is possible with a stimulus of this type. Through this, a better synchronization of the neural response can be obtained and, as a result, higher response amplitudes can be expected, particularly for low-frequency stimuli. The additional introduction of a frequency offset enables the use of a q-sample test for the response detection, especially important at 500 Hz. The results of investigations carried out on a large group of normally hearing test subjects have confirmed the efficiency of this stimulus design. The new stimuli lead to significantly improved ASSRs with higher SNRs and thus higher detection rates and shorter detection times.

Acoustic Stimulation↗

PubMed2005

Automated auditory response detection: statistical problems with repeated testing.

Sequential application of a statistical test is usually applied in an automated auditory response detection algorithm. The sequential test strategy is very time-efficient but increases the probability of a false rejection of the null-hypothesis. For this reason, it is necessary to correct the critical test value. However, the well-known Bonferroni correction leads to an over-correction when dealing with dependent or partly dependent data. The objective of the study reported here was to develop a method to determine the critical test value for the sequential testing of dependent data. Extensive Monte Carlo simulations were used to develop this method. The simulation results were reviewed and the benefit of the suggested method, in comparison to the Bonferroni correction, was shown using a large sample of real amplitude modulation following response data. The detection rate determined for these data and the ROC curve demonstrate the advantage of using the method suggested here.

Algorithms↗

PubMed2003

Benefits from hearing aids in relation to the interaction between the user and the environment.

It is becoming increasingly recognized that, in addition to the influence of audiometric variables and associated psychoacoustic abilities, the benefits from and candidature for various signal-processing schemes in hearing aids are strongly influenced by listeners' characteristics (such as motivations, expectations, and personality), and also the auditory environments in which those listeners are required to function (i.e. their auditory ecology). We will report elsewhere an experiment on a group of 50 listeners in a within-subject, randomized, blind, crossover design of five different hearing aid rationales, of which two contained linear amplification and three contained non-linear amplification which differed only in release-time constant. This article reports the interaction between the audiometric and cognitive characteristics of listeners, and the test conditions under which speech identification procedures are conducted (presentation level, signal-to-noise ratio, and temporal characteristics of interfering noise). The analyses show significant interactions between hearing impairment and cognitive ability, and the extent to which, when tested unaided, listeners can derive advantage from temporal structure in a background noise. The analysis then addresses the benefits of amplification (defined as the difference between performance in the amplified and unaided conditions) and shows significant interactions between cognitive ability, the temporal characteristics of interfering noise, and the time constants of non-linear amplification rationales. The direction of the interaction is that listeners with greater cognitive ability derive greater benefit from temporal structure in background noise when listening via fast time constants, one of whose effects is to facilitate 'listening in the gaps'.

Amplifiers, Electronic↗