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Biomedical subjects

L Jerlvall

Publications and source records attributed to L Jerlvall.

10 recordsLinked to original sources
PubMed1986

A comparison of 2-dB and 5-dB step size in pure-tone audiometry.

With the purpose of comparing test-retest reliability, pure-tone audiometry with a step size of 2 and 5 dB using the ascending technique was performed on two groups of subjects. One group consisted of 10 normal-hearing subjects and the other of 10 subjects with moderate cochlear hearing loss. The statistical analysis of the overall estimation of standard deviation obtained with the different step sizes showed no significant difference in any group. However, at 3 000 and 4 000 Hz in the cochlear group a significantly lower standard deviation was obtained with the smaller step size. The number of threshold crossings required to fulfil the threshold criterion increased significantly with the smaller step size.

Adolescent↗
PubMed1983

Comparison of manual and computer-controlled audiometry using identical procedures.

Ten normal-hearing subjects were evaluated with both manual and computer controlled audiometry using the ascending threshold determination method as proposed by ISO. The study shows that the thresholds obtained with the two different techniques correlate well and that standard deviations for the test--retest difference are significantly lower in the computer-controlled situation. The results also indicate that computer-controlled audiometry may be of importance in general clinical applications giving rapid and reliable threshold determination.

Adult↗
PubMed1982

Calculation of hearing results after tympanoplasty.

At present there is no universally accepted method for calculating hearing results after chronic ear surgery. In this study the methods most frequently used have been applied to a material of 105 tympanoplasties and compared to each other. In addition a comparison between pre- and post-operative bone conductions (BC) thresholds for calculating post-operative air-bone gaps has been performed using multiple regression analysis. The results lend support to the conclusion that BC thresholds will improve with surgery in successful cases and that the post-operative BC threshold is a closer approximation of the cochlear function than the pre-operative one and consequently should be used for gap calculations. However, until the masking procedures in audiometry are standardized, hearing gain may be regarded as the most satisfactory alternative for describing hearing results as it is based on the air conduction thresholds only. This method requires a careful description of pre-operative air and bone conduction thresholds.

Audiometry↗
PubMed1982

Reliability of bone-conducted electrocochleography. A clinical study.

The correlation between pure-tone bone conduction thresholds (BC) and thresholds obtained by electrocochleography with bone conducted stimulation (BC-ECoG) for 1, 2, 4 and 8 kHz was studied in 26 ears due for ear surgery. The correlations proved to be statistically highly significant and the results lend support to the conclusion that BC-ECoG can be considered to be well adapted for clinical use in cases where conventional audiometry has failed to reveal the capacity of the cochlea.

Audiometry↗
PubMed1981

Early auditory electric responses to fast amplitude and frequency tone glides.

Using the standard far-field technique for auditory brain stem responses early electrical responses have been recorded, evoked by stimulation using brief frequency or amplitude glides of a continuous pure tone of 1 kHz at 60 dB HL. The glide duration was always 1 msec and its magnitude in the range of 50--100% relative frequency change or 5--20 dB sound level change. Ten normal-hearing subjects were studied. The responses recorded were generally dominated by a vertex positive-negative-positive wave complex in the 4--9 msec latency range. The wave form was significantly different from the AER evoked by clicks or brief tone bursts. The origin of the different response components is not clear; a cochlear origin of the first vertex-positive component is a possibility. Although responses to frequency and amplitude glides were similar in most respects there were some statistically significant differences which may be related to different auditory processing of amplitude and frequency modulation. Distinctly clearer responses were recorded to positive glides, i.e., increasing frequency or amplitude, than to negative glides. This is in contrast with psychoacoustic detection thresholds and slow cortical responses to frequency glides, which have shown essentially symmetry, but in agreement with such findings in response to amplitude glides. The findings do not agree with previously published results on VIII nerve compound action potentials in response to brief frequency glides.

Acoustic Stimulation↗
PubMed1980

Ossicular manipulation in chronic ear surgery. An electrocochleographic study.

Twelve patients were submitted to ossicular dissections for between 2 1/2 and 35 minutes during ear surgery. A comparison between premanipulatory and portmanipulatory electrocochleographic threshold determinations did not disclose any thrshold shifts. The results lend support to the conclusion that manipulations on ;the ossicular chain, performed with customary care, are less harmful to the inner ear than other generally recognized threats to the cochlea during surgery, eg, perilymph fistulae and acoustic traumas from the drill.

Cochlea↗
PubMed1975

Vestibular and somatosensory inflow to the vestibular projection area in the post cruciate dimple region of the cat cerebral cortex.

In anesthetized cats 251 cells within the cortical vestibular projection area, adjacent to the post-cruciate dimple, were analyzed as to their input characteristics employing extracellular recording techniques. The post cruciate dimple vestibular field, which is located in area 3a, has a high degree of convergence between vestibular and peripheral somatosensory input. The latter is not restricted to muscle afferents but includes cutaneous modalities. The functional significance of this vestibular cortical projection field is discussed.

Animals↗