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Biomedical subjects

E Laukli

Publications and source records attributed to E Laukli.

At least 19 recordsLinked to original sources
PubMed1992

Threshold of hearing (0.125-20 kHz) in children and youngsters.

Pure-tone air-conduction audiometry has been performed in three groups of children and youngsters aged 10, 14 and 18 years old. The complete frequency range of 0.125 to 20 kHz was measured, and number of different questions were raised. Firstly, the hearing threshold in the conventional frequency range was compared to the international standard ISO 389. Significant differences from ISO zero were found for all groups and at all frequencies of 0.125 to 8 kHz. Secondly, possible noise damage, shown as dips in the audiograms at 3, 4 or 6 kHz was examined; and thirdly, high-frequency (8-20 kHz) sensitivity between groups was compared. Only a few audiograms, the majority being in the youngest age group, were found to be a result of possible noise damage, and in the extra-high-frequency range, a systematic decrease in sensitivity was found for the two older groups compared to the 10-year-old children at frequencies higher than 14 kHz.

Adolescent↗
PubMed1990

Reproducibility of hearing threshold measurements. Supplementary data on bone-conduction and speech audiometry.

The reproducibility of bone-conduction pure-tone audiometry and speech recognition thresholds has been tested in groups of normal-hearing subjects. Each person was tested twice during the same day, and the test-retest difference was calculated. The reproducibility is presented as the standard deviation of this difference. Bone-conduction threshold measurements have a high degree of test-retest precision, whereas air-bone gaps show a large range of distribution in these normal-hearing subjects. This makes the interpretation of such gaps spurious when values are below 20-30 dB. Speech recognition threshold has the highest degree of test-retest precision of all audiometric tests, and this is probably due to the steep slope of the psychometric function at 50% intelligibility. A more detailed graphic presentation of the 50% point of intersection will bring the reproducibility down to less than 2.5 dB.

Adult↗
PubMed1989

[Hearing loss in children. Diagnostic challenges].

Auditory brain stem response thresholds have been determined in 142 anaesthetized children who were difficult or impossible to assess using conventional behavioural audiometry techniques. Auditory brain stem response was later compared with puretone thresholds in the 2-4 kHz range, and an acceptable auditory brain stem response reliability was demonstrated. Using the auditory brain stem response results as a basis, we analysed some parental and behavioural auditory aspects in order to obtain a reliable diagnosis of hearing at a younger age than hitherto.

Adolescent↗
PubMed1989

Audiometric results of TORP and PORP middle ear reconstruction.

The results of 70 middle ear reconstructions using either total or partial ossicular replacement prostheses are presented, the mean observation period being 45 months. Twenty-seven of the prostheses (39%) were extruded, this occurring as late as 72 months after surgery, and four (6%) were removed at reoperation. The surgical results when assessed by the magnitude of the air-bone gap are comparable to those of other series in the literature. However, postoperative air conduction thresholds remained high, and 23% of the patients are using hearing aids. The average air-bone gap for the frequencies 0.5, 1, and 2 kHz does not provide information on patients' everyday hearing level, and should no longer be employed as an index for assessing the functional results of middle ear surgery.

Audiometry↗
PubMed1989

Air conduction thresholds and secretory otitis media: a conventional and extra-high frequency audiometric comparison.

A comparison has been made of air conduction threshold changes up to 1 year after myringotomy, aspiration of middle ear fluid, and insertion of ventilation tubes in ten patients with bilateral and 12 with unilateral secretory otitis media (SOM). Pure tone air conduction thresholds have been analyzed in three frequency groups: low frequency (LF; 0.25 0.5, and 1 kHz), high frequency (HF; 2, 4, and 8 kHz), and extra-high frequency (EHF; 10, 12, 14 and 16 kHz). In the LF and HF ranges, significant improvement came during the first 24 hours after intubation, while in the EHF range, threshold lowering occurred gradually over the following 2 months. Possible explanations for these findings are discussed.

Adolescent↗
PubMed1989

Paediatric auditory brainstem response and pure-tone audiometry: threshold comparisons. A study of 142 difficult-to-test children.

Auditory brainstem response (ABR) thresholds have been determined in 142 anaesthetized 'difficult-to-test' children. The stimuli employed were 2-kHz tone bursts. Pneumatic otomicroscopy was carried out prior to the ABR assessment in all cases, and diagnostic myringotomy was performed when there was the slightest suspicion of abnormality. Long-term follow-up pure-tone audiograms were obtained in 56 patients. A comparison was made between ABR and pure-tone thresholds in the 2-4 kHz range both in healthy middle ears and in ears having middle ear effusion (MEE) at the time of ABR measurement. A correction factor for prediction of behavioural threshold from the ABR threshold both in healthy and in MEE ears is proposed.

Adolescent↗
PubMed1989

Low-level 0.5 and 1 kHz auditory brainstem responses. A search for the low-frequency point in the two-point ABR audiogram.

We have compared the auditory brainstem responses (ABRs) to 0.5 and 1 kHz tone burst stimuli with high-pass noise masking in 10 normal-hearing adults. The overall quality of the low-level responses was poor, but a two-point ABR audiogram is feasible by using the summation technique described. The 1 kHz stimulus gave slightly better responses than 0.5 kHz, and a correction factor of 30-40 dB seems necessary. Our data indicate that these low-level, low-frequency responses are frequency-specific.

Adult↗
PubMed1988

High-frequency audiometry: air- and electric bone-conduction.

Normative values have been obtained for high-frequency air- and electric bone-conduction thresholds in different age groups. Reproducibility with both methods is of the same order of magnitude as with conventional audiometry. The two thresholds can be compared and the air-conduction/electric bone-conduction gap obtained by transforming the electric bone-conduction values to a dB notation by means of a formula containing a frequency-dependent constant.

Adult↗
PubMed1988

High-frequency audiometry: comparison of electric bone-conduction and air-conduction thresholds.

Thresholds have been measured with two commercially available high-frequency (HF) audiometers providing respectively air-conduction (AC) and electric bone-conduction (EBC) stimulation. Normative values for the latter have been obtained, and the reduction of HF sensitivity with both stimulus modes documented in two groups aged 50-59 and 70-79 years. EBC reproducibility is of the same order of magnitude as the AC signal through 14 kHz, while the dynamic range is limited to 50 dB. Lateralization of the EBC signal occurs up to at least 17 kHz. The logarithmic conversion factor of Tonndorf and Kurman [Ann. Otol. Rhinol. Lar. 93: 576-582, 1984] does not result in equivalent AC and EBC thresholds at all frequencies, but does provide similar loudness sensation increases. The 40 log (i) re 1 mA conversion factor must be adjusted with a frequency-dependent additive correction.

Adult↗
PubMed1988

Screening for retrocochlear pathology.

In 1982, 135 patients were screened for possible retrocochlear pathology, by means of an investigation protocol consisting of caloric test, impedance audiometry and brainstem response audiometry (BRA). A combination of the first two of these procedures had an unacceptably low prognostic accuracy. BRA indicated retrocochlear pathology in 8 and was inconclusive in 4 cases. Enhanced computer tomography revealed an intracranial tumour in 4 of the former, while no space-occupying lesion could be demonstrated in the remainder nor in the 4 patients with inconclusive BRA. BRA is the best single test for screening of this patient category.

Acoustic Impedance Tests↗
PubMed1988

Low-frequency auditory brainstem response threshold.

Auditory brainstem thresholds have been determined in 35 non-cooperative, anaesthetized children using a 'two-point audiogram' paradigm. The high-frequency point was found with a 2 kHz tone-burst without masking, and the low-frequency with a 0.5 kHz tone-burst together with 1 kHz high-pass noise masking. Great variability was found in the low-frequency thresholds, and only 3 of 18 ears with normal high-frequency thresholds had low-frequency thresholds below 70 dB nHL. It is concluded that the 0.5 kHz tone-burst with 1 kHz high-pass noise masking is not a reliable method for routine assessment of low-frequency auditory threshold at the brainstem level.

Adolescent↗
PubMed1988

Auditory brainstem responses and extratympanic electrocochleography. A threshold comparison in children.

Electrocochleography (ECoG) and auditory brainstem response (ABR) have been recorded simultaneously in 23 children referred for threshold evaluation. The ECoG electrode is an extratympanic silver ball (Life-Tech) whereas the ABR is recorded with Ag-AgCl surface electrodes. Of the 30 ears investigated according to this protocol, 11 had no response with either technique, and in a further 11 no difference was found between ECoG and ABR thresholds. In the remaining 8 ears, ABR threshold was lower in 6 and the ECoG in 2. We conclude that the extra time needed for cleansing the ear canal and inserting the electrode does not justify the use of ECoG in threshold evaluations, since the ABR alone has the necessary sensitivity.

Adolescent↗
PubMed1986

Low-frequency hearing loss: auditory brainstem response-derived band analysis.

Conventional (0.125-8 kHz) and high-frequency (8-20 kHz) audiometry, together with brainstem response audiometry supplemented with derived-band studies have been performed in 6 patients with sensorineural hearing loss: 1 with narrow-band, 3-4 kHz, and 5 with low-frequency threshold elevations. The derived-band results in the latter indicate that the low-frequency audiometric thresholds are spurious, and represent the low-frequency tails of viable high-frequency neurons. Threshold preservation in the 4- to 8-kHz frequency band proved necessary for generation of a normal auditory brainstem response at suprathreshold stimulus levels.

Adolescent↗
PubMed1986

Frequency specificity of the auditory brainstem responses. A derived-band study.

Auditory brainstem responses evoked by both clicks and 0.5 kHz tone-bursts were recorded using the derived-band paradigm in 10 normal-hearing subjects. The derived-band analyses showed a similar distribution of activity with both stimuli, the largest contributions coming from the 2-4 and 4-8 kHz bands. Neither the click nor the 0.5 kHz tone-burst is a frequency-specific stimulus, and both would appear to be unsuitable for brainstem response audiometric evaluation of the apical cochlea.

Acoustic Stimulation↗
PubMed1985

Auditory brainstem responses of the cat: on- and off-responses.

The auditory brainstem on- and off-responses evoked by tone and noise bursts have been studied in the cat. The number and amplitude of the off-response waves are proportional to the frequency specificity of the on-response, being greatest for the 4-kHz tone burst and smallest for the noise burst. The threshold of the 0.5-kHz off-response is lower than that of the on-response, but the amplitude of the former does not increase at higher stimulus levels. Derived-band studies show that at 4 kHz the on-and off-responses have identical frequency content, the 0.5-kHz off-response is restricted to the 2- to 8-kHz frequency band, while the noise burst off-response is entirely high frequency. The off-response is an on-response and is evoked by acoustic transients from the loudspeaker transducer.

Acoustic Stimulation↗
PubMed1985

Low-frequency sensorineural hearing loss. Brainstem response, speech and high-frequency audiometry.

Four cases of acquired, unilateral sensorineural hearing loss are presented. The low-frequency octave threshold changes are considered compatible with the low-frequency tails of neurons with characteristic frequencies of 2, 4 and 9 kHz. Zero speech discrimination was found in two patients with high-frequency threshold preservation at and above 4 kHz. Normal auditory brainstem responses were obtained in the two patients with low-frequency hearing loss confined to the frequency bands below 2 and 4 kHz respectively. Only wave I could be reliably identified in the two patients with single frequency threshold preservation at 2 and 9 kHz, while both presented a second, low amplitude wave with latency corresponding to our normative values for wave V. The latter may represent a delayed and pathological wave III.

Adolescent↗