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Biomedical subjects

C Elberling

Publications and source records attributed to C Elberling.

At least 19 recordsLinked to original sources
PubMed1990

Hearing disorders in patients with insulin-dependent diabetes mellitus.

The cochlear and retrocochlear hearing function was evaluated in patients with long- and short-term insulin-dependent diabetes mellitus (IDDM) by means of psychoacoustic testing and auditory brain stem responses (ABR). Twenty patients with diabetic microangiopathy (median age 41 years, range 25-66 years) were examined. The median duration of their diabetes was 26 years (range 13-46 years). In addition, 19 patients without microangiopathy (median age 27 years, range 17-42 years) and with a median duration of the diabetes of 2 years (range 0-6 years) were examined. The metabolic control estimated by blood glucose concentration and glycosylated haemoglobin was identical in the two groups of IDDM patients. After correction for age and sex, no significant differences in hearing thresholds or discrimination scores were present between the two diabetic groups, or between the diabetic patients and an age- and sex-matched normal background population. In the patients with long-term IDDM, ABR produced abnormal responses in 40%, indicating the presence of diabetic encephalopathy, whereas ABR were abnormal in only 5% of the patients with short-term IDDM.

Acoustic Impedance Tests↗
PubMed1990

Prediction of intelligibility of non-linearly processed speech.

Speech in various noise backgrounds was processed through four different non-linear devices and the intelligibility of the processed signals was predicted from the Speech Transmission Index (STI). A novel calculation method was applied in order to avoid artifacts. Running speech was used as input signal and STI was calculated from the envelopes of the squared, noise-free speech signal and of the processed, squared, noisy signal in 23 critical bands. In situations with linearly processed speech and a stationary background noise, this calculation method gives results identical with the procedure described by Steeneken & Houtgast (6). However, in a number of situations with non-linearly processed speech, or a time varying background noise level, the calculation method used here is preferable. The predictions were evaluated in a psycho-acoustic listening test and the predictions agreed well with the listening test results.

Hearing Aids↗
PubMed1989

Evoked acoustic emissions from the human ear. V. Developmental changes.

Twenty young children, in whom evoked acoustic emissions were recorded at birth, were re-examined at the age of 4 years. None of the children showed evidence of sensorineural hearing impairment and it was possible to record a reproducible emission in all ears, which displayed normal otoscopy and tympanometry (n = 9). The new recordings were compared with those obtained at birth and the latency and the amplitude of the response both appeared unchanged. However, in some ears the frequency content of the dominant part of the emission was considerably lower at the age of four. The implication of this finding is briefly discussed in view of recent data on cochlear development, obtained from animal research.

Child, Preschool↗
PubMed1989

DANTALE: a new Danish speech material.

A new Danish speech material (DANTALE) for clinical and experimental speech audiometry is digitally recorded on compact disc (CD). The speech material is designed to meet present audiological requirements at Danish hearing centres. One channel of the CD contains the speech signals and the other a masking noise. The CD also contains various calibration signals recorded on both channels at the end of the CD. The speech material compromises: 1) Digit triplets for the measurement of speech reception threshold (SRT). 2) Lists of monosyllabic words for the measurement of discrimination score (DS) for adults, children and small children. The word lists for the adults are equalized with regard to important phonetic and "visual" elements and the word lists for the children consist of minimal pairs. 3) Continuous speech for the measurement of the most comfortable loudness level (MCL), assessment of hearing aid fitting and the like. The masking noise is an amplitude-modulated, speech-shaped noise signal, which is designed to simulate a 4-person speech babble in order to assess both the frequency selectivity and the temporal resolution. The speech material is described and the long-term power spectra and modulation spectra are given.

Audiometry, Speech↗
PubMed1988

Evoked acoustic emissions from the human ear. IV. Final results in 100 neonates.

Evoked acoustic emissions were recorded from both ears in a series of 100 consecutive normal newborns. We used the same stimulus, a 2-kHz click, and recording technique as previously described. Analysis of the data showed that evoked emissions could be identified in all ears, except one at 70 dBaud (i.e. approximately 30 dB nHL). No significant differences could be demonstrated between males and females or between left and right ears with regard to the latency of the emissions, the peak-to-peak amplitude, the main frequency component, or the waveform correlation between the two 70 dBaud recordings in each ear. However, a significant correlation between left and right ears was found for the amplitude and frequency of the emissions. Practical and methodological problems related to the recording were elucidated. The tail of the stimulus artifact sometimes interfered with the first part of the emissions even though the recordings were made in a time window delayed 5 ms relative to the stimulus onset. We tried to solve this artifact problem by different off-line techniques, but found no useful solution. We therefore continued to use only a cosine tapering of the first 2 ms of the time window. Three different ways of determining latencies were evaluated and we found that the 'envelope' technique was the most simple and reliable. Recording of evoked acoustic emissions is a quick and non-invasive method and provided that the presence of the emissions is related to normal cochlear function, it can be used as a screening test in newborns.(ABSTRACT TRUNCATED AT 250 WORDS)

Audiometry, Evoked Response↗
PubMed1987

Threshold characteristics of the human auditory brain stem response.

Auditory brain stem responses (ABRs) were recorded from ten normal-hearing subjects in response to 100-microseconds clicks from a TDH 49 earphone at a rate of 48 pps and at levels randomly varied in 2-dB steps between 34 and 52 dB p.e. SPL. At each level, 10 000 epochs were averaged with use of a weighted concept and a running estimate was made of the signal-to-noise ratio (SNR). This quantity was used to detect the presence of the ABR and the median threshold was found at 38 dB p.e. SPL. The mean averaged background noise level was 11.3 nVrms, and the "true" ABRrms amplitude function crossed this value at 35.5 dB p.e. SPL, which indicates the level where the SNR = 1. By extrapolation, it was found that the ABR amplitude became zero at 32 dB p.e. SPL. The perceptual thresholds of the click were estimated by means of a modified block up-down procedure, and the median value was found at 33 dB p.e. SPL. The slope of the amplitude function and the magnitude of the averaged background noise are the two factors responsible for the ABR threshold sensitivity, which thus depends on both physiological and technical parameters. Therefore, these have to be considered together with the method of detection when the ABR is used to indicate the hearing sensitivity.

Auditory Threshold↗
PubMed1987

Reference data for ABRs in retrocochlear diagnosis.

A retrospective analysis has been carried out on the auditory brainstem responses obtained in 235 female and 249 male neurologically normal patients. The analysis is focused on the wave latencies and the I-V and I-III intervals are compared with the classification parameters sex, age and high-frequency hearing loss. Since age and hearing loss are correlated, a multiple regression analysis is used to analyse the effects from the two variables. Both intervals are found to differ with sex (i.e. females display smaller values than males), to increase with age, and to decrease with hearing loss. Corrections are made for the classification parameters relative to 25 years and 0 dB HL. For the I-V interval, we find a mean value of 4.01 ms for the females and 4.19 ms for the males and a residual variance (SD) of 0.20 ms. For the I-III interval, we find a mean value of 2.13 ms for the females and 2.27 ms for the males and a residual variance (SD) of 0.16 ms. However, for the I-III interval, only the male data show dependence of hearing loss. In 78 patients, the electrocochleographic N1 is used to ensure the wave I latency and there is in general a good agreement between the two latency measures. However, in patients with profound high-frequency hearing loss differences up to 0.5 ms can be found.

Adult↗
PubMed1987

Detection functions for the human auditory brainstem response.

Previously obtained data characterizing the auditory brainstem response near the threshold for detection in 10 normal-hearing subjects are used to evaluate the detection method applied. The basic detection formula is described in terms of rates of true positive and false positive ABR detection and in combination with the normative ABR values used to calculate the ABR detection functions as well as the corresponding receiver operating characteristics (ROC curves). The observed distribution of the ABR-threshold levels is similar to that derived from the detection function, and therefore verifies the present results which are based partly on theoretical considerations.

Auditory Pathways↗
PubMed1985

Evoked acoustic emission: clinical application.

Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only a minor effect on the power spectra, i.e. the maximum jumps from one spectral peak to another. Experiments with deconvolution demonstrate that the emission generating system at least at a fixed intensity can be regarded as being linear and characterized by its impulse response which is similar to the emission evoked by click stimuli. It is concluded that significant information is obtained by the click rather than by the tonal stimuli. The click-evoked emissions were also recorded from both ears in a consecutive series of 100 full-term and otherwise normal babies 2-4 days after birth. The emission amplitudes were of the same order of magnitude as those previously found in normal-hearing adults. Cross-correlation analysis was performed in order to evaluate reproducibility and the combination of amplitudes and correlation coefficients from supra-threshold recordings and the no-stimulus recordings reveals presence of a true emission from all ears tested. It is concluded that the cochlear echo can be recorded in normal-hearing newborns with an extremely low rate of type I errors.

Adult↗
PubMed1985

Estimation of auditory brainstem response, ABR, by means of Bayesian inference.

The present paper describes a new method to estimate the auditory brainstem response when the electrical activity from the recording electrodes displays non-stationarity, i.e. varies between low and high levels. The method is based on a statistical approach called Bayesian inference and weights the individual components (here blocks of 250 sweeps) inversely proportional to the level of the noise activity during the recording. Fifty sets of data from 10 consecutive patients obtained during stimulation at high intensity are used to evaluate the difference between the classic averaging and the present method which is called Bayes estimation. In approximately 30% of the cases, a significant all-over improvement is obtained by the new method. The classic averaging technique would here require 50% more sweeps to be taken to obtain the same precision of the ABR estimate, on average. Also the latency and amplitude parameters of the Jv wave complex are evaluated and it is shown that the parameter variance decreases by a factor of approximately 2 by using the Bayes estimation. The new technique is compared with a similar technique recently presented by Hoke et al. (1984) and the differences and similarities are discussed.

Bayes Theorem↗
PubMed1979

Auditory electrophysiology. The use of templates and cross correlation functions in the analysis of brain stem potentials.

A method for the objective analysis of acoustically evoked brain stem potentials, BSER, is proposed. Recordings from 24 patients with pure cochlear hearing losses are adjusted in amplitude and time, and used to produce normative BSER waveforms serving as templates. The cross-correlation function between the individual, adjusted BSER recording and the corresponding template is calculated, yielding an objective measure of the BSER waveform and gross latency. Clinical application of the method has given encouraging results.

Brain Stem↗
PubMed1978

Estimation of the critical bandwidth from loudness summation data.

An automatic method for critical band estimation from loudness summation data is presented. A mathematical model, based on a power function, is fitted to the data and the critical bandwidth is defined at the intersection of the asymptotes. The model is designed for clinical use, involving the treatment of the data from single test persons; it represents an operational solution to a difficult task. The model is able to describe data from normals and patients with a sensorineural hearing loss. Variability of the critical band estimates, intrasubject as well as intersubject, is larger than for visually obtained estimates. However, visual estimation is difficult, subjective, and probably heavily biased. The model produces estimates which in logarithmic form have a Normal distribution at medium loudness level, while visual estimation gives rise to irregular distributions at all levels. A normal range for model estimates from sets of data obtained at medium loudness level is defined by mean and standard deviation.

Auditory Perception↗
PubMed1978

Compound impulse response for the brain stem derived through combinations of cochlear and brain stem recordings.

To overcome some of the problems involved in the application of brain stem evoked responses (BSER) in otoneurological diagnosis an approach is developed which combines cochlear and brain stem recordings. The activity of the cochlea and brain stem generators, as seen from the far-field recording electrode, is considered to be the output from a single system. The impulse response of this system can be derived through deconvolution of the brain stem evoked responses, BSER, with the compound action potential, AP, followed by appropriate filtering. This method is used on the recordings from 15 subjects with various degrees of cochlear hearing loss. The results show that the compound impulse response, CIR, for the brain stem consists of five recognizable peaks. From the individual subjects this response pattern is largely independent of intensity. By plotting the amplitude and latency of the individual peaks for all 15 subjects a set of normative data is retrieved. The variation in the data is small, probably because interfeerence from the periphery is eliminated and the separation of activity from the different brain stem generators is improved.

Audiometry↗