N J Johnsen

Learn More
The purpose of the present study was to determine the utility of auditory evoked magnetic fields as an objective measure of tinnitus. The auditory evoked magnetic fields of 14 patients with tinnitus and of 14 sex- and age-matched controls were measured by means of a 7-channel BTI neuromagnetometer. Stimuli were 1 kHz tone-bursts presented randomly. Tinnitus(More)
Stimulated acoustic emissions were recorded in a consecutive series of 20 full-term and otherwise normal neonates with the equipment and method previously used in adults. One ear randomly chosen was tested in each baby, and otoscopy and tympanometry were normal in all ears. A 2 kHz click stimulus was presented with a repetition rate of 10/sec and the(More)
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(More)
Using signal averaging technique, stimulated acoustic emissions can be recorded from the human ear with a probe in the external ear canal. An acoustic click stimulus was used, produced by half a sinusoid of 2 kHz with the polarity corresponding to the rarefaction mode. A number of different techniques were developed in order to evaluate the latency and(More)
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(More)
Click-evoked acoustic emissions were recorded in 10 normally hearing young adults and evaluated by methods previously described. Five of the subjects were tested on both ears. A clear response could be traced down to or below the psychoacoustic threshold in all ears. However, the response pattern differed significantly from one ear to another, yielding an(More)
Click-evoked otoacoustic emissions (CEOAE) were recorded in 28 subjects with mild to moderate flat or steeply sloping cochlear hearing loss. We used the same equipment and recording technique as previously employed in the testing of newborns. A rescaling and subtraction procedure was implemented in an attempt to eliminate the tail of the stimulus artifact.(More)
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(More)
The acoustic middle ear muscle reflex thresholds towards white noise and fast sequences of clicks were determined in 46 normal-hearing young adults using electronic averaging. For white noise the thresholds were normally distributed around an average value of 72.7 dB SPL. With sequences of clicks the threshold depended above all on the click repetition rate(More)
Auditory and vestibular function was monitored in 30 patients treated with netilmicin for urinary tract infection. During and after the treatment, no signs or symptoms appeared that could be ascribed to an ototoxic effect of the drug. Routine acoustico-vestibular tests as well as advanced, objective acoustic tests revealed no signs of impairment of the(More)