[Effect of stimulus rise time and high-pass masking on early auditory evoked potentials]. / Der Einfluss der Reizanstiegszeit und der Hochpassmaskierung auf die frühen auditorisch evozierten Potentiale.
Laryngorhinootologie
; 77(4): 185-90, 1998 Apr.
Article
em De
| MEDLINE
| ID: mdl-9592750
ABSTRACT
BACKGROUND:
Problems of frequency-specific objective assessment of hearing threshold by means of auditory brainstem response (ABR) have been discussed recently. While a number of workers have recommended methods of selective masking to improve the frequency specificity, others believe that frequency-specific potentials can also be obtained without masking. In this context, the effects of rise-decay time and high-pass masking on ABRs were investigated.METHOD:
ABRs were recorded in normal-hearing subjects and patients with high and low frequency hearing loss by means of surface electrodes between the vertex and the ipsilateral mastoid. The frequency of the stimulus was 1 kHz, and the rise-decay time 1 ms (1-0-1) or 2 ms (2-0-2). High-pass filtered noise (cutoff frequency 1.5 kHz; filter slope 250 dB/octave) was employed for masking. Particular attention was paid to the problem of efficient masking.RESULTS:
In normal-hearing subjects under the influence of high-pass masking compared to non-masked ABRs, longer mean latencies and diminished means of the amplitudes of wave V were found, with differences in the near-threshold domain being less pronounced. Similar results were observed in patients with high frequency hearing loss. In patients with low frequency hearing loss, the influence of high-pass masking was especially marked distinctly near to threshold. Furthermore, latency and amplitude differences of wave V of the 1-0-1 and the 2-0-2 stimuli were determined from the ABRs obtained with and without high-pass masking. The differences between the latency differences of both stimuli in the suprathreshold range (70 dB nHL) only were statistically significant.CONCLUSIONS:
The results are suggestive of an inadequate frequency specificity of unmasked stimuli in the suprathreshold range. Evaluation of the latencies revealed for both rise-decay times a similar frequency specificity near the threshold and a higher frequency specificity of the longer stimulus in the suprathreshold range.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Mascaramento Perceptivo
/
Audiometria de Resposta Evocada
/
Limiar Auditivo
/
Potenciais Evocados Auditivos do Tronco Encefálico
/
Perda Auditiva de Alta Frequência
/
Perda Auditiva Neurossensorial
Tipo de estudo:
Etiology_studies
Limite:
Adult
/
Female
/
Humans
/
Male
/
Middle aged
Idioma:
De
Revista:
Laryngorhinootologie
Ano de publicação:
1998
Tipo de documento:
Article