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Biomedical subjects

S Prosser

Publications and source records attributed to S Prosser.

At least 37 records · Page 2Linked to original sources
PubMed1990

Effects of different noises on speech discrimination by the elderly.

Elderly people often complain of difficulty in speech discrimination, especially in noise environments. The effects of 4 competing noises on sentence intelligibility were evaluated: speech noise, cocktail party noise, traffic noise and continuous discourse. A comparison was made between young and old normally hearing subjects and young and old hearing-impaired subjects with similar audiograms. The old people with normal hearing had slightly reduced discrimination compared to the young during competing speech noise and cocktail noise. Discrimination in the hearing-impaired elderly was also significantly worse than in the young people with normals hearing, during competing cocktail party noise, traffic noise and continuous discourse. The young hearing-impaired had results between young normal-hearing subjects and old hearing-impaired, except for continuous discourse. Thus the effects of age on speech discrimination in noise are subtle, becoming more pronounced in the presence of hearing loss. Age-related changes in primary speech discrimination were particularly evident during competing continuous discourse.

Adult↗
PubMed1988

Hearing loss in sports hunters exposed to occupational noise.

The hearing level of 133 railway workers who also hunted for sport was evaluated and compared with that of 82 non-hunting colleagues. Both groups were affected by hearing loss, mostly involving the high-frequency range. Hunters were found to differ from non-hunters by having significantly worse hearing threshold in the ear contralateral to the shoulder supporting the firearm. The interaural threshold difference at 4 kHz was related to the number of rounds fired and exposure duration, thus providing an estimate of the adverse effect of gunfire noise to which the hunters had been exposed.

Adult↗
PubMed1987

Prediction of auditory brainstem wave V latency as a diagnostic tool of sensorineural hearing loss.

The lesion location (cochlear vs. retrocochlear) of sensorineural hearing loss may be differentiated with a diagnostic index (delta V), which is calculated from the wave V latency of the monaurally evoked auditory brainstem response (ABR), and from the pure-tone hearing threshold at 2 and 4 kHz. The delta V values obtained from 80 recruiting ears have proven to correlate linearly to the amount of the hearing loss, hence allowing to define appropriate confidence boundaries for cochlear hearing losses. In contrast, the delta V values obtained from 32 ears of patients with retrocochlear lesions--cerebellopontine angle (CPA) tumors--were all found to exceed the 95% upper confidence limits projected for cochlear lesions, thus giving a 100% rate of true results in the detection of retrocochlear pathology. These results, providing an ABR parametric model for the cochlear hearing loss, suggest a diagnostic strategy for the early detection of CPA tumors based on the exclusion of a cochlear hearing loss.

Brain Stem↗
PubMed1986

Nasal airflow asymmetries and human performance.

Recent studies of the nasal cycle and forced uni-nostril breathing have demonstrated that integrated EEG amplitudes are greater over the hemisphere contralateral to the dominant (less congested) or unblocked nostril. Two experiments were designed to determine if asymmetries in nasal airflow, occurring naturally as a result of the nasal cycle or artificially as a result of forced uni-nostril breathing have consequences for human performance on verbal and spatial tasks that are preferentially performed by the left and right hemispheres respectively. A significant relationship was obtained between the pattern of nasal airflow with normal breathing and relative spatial vs verbal performance. Forced uni-nostril breathing had no effect on performance.

Female↗
PubMed1985

Does general anaesthesia affect the child's auditory middle latency response (MLR)?

Auditory MLR and ABR were recorded simultaneously in 9 children under general anaesthesia, after electrocochleography had demonstrated a normal hearing threshold. In contrast to the ABR components which in all cases appeared to be clearly recognizable, and with latencies within the normal range, MLR revealed gross abnormalities represented by instability of the components and abnormal latency of the detectable peaks. Since such variations in the MLR pattern may be thought of as a direct consequence of general anaesthesia, it seems likely that these potentials reflect a neural activity which, in children, is affected by CNS drugs.

Anesthesia, General↗
PubMed1985

Quantitative analysis of vestibular response in cerebello-pontine angle tumors.

The results obtained by vestibular examination are reported for 20 patients with cerebellopontine angle tumours. Eye pursuits, spontaneous, positional and caloric induced nystagmus (lateral and directional preponderance for duration, frequency and speed of slow phase) were evaluated in order to identify the most sensitive parameter. Half cases showed abnormalities in eye tracking test, one third a spontaneous nystagmus, 5% only a positional nystagmus. A lateral preponderance of the healthy side was found in 95% of the cases when calculated on the slow phase velocity of the caloric nystagmus, while lower rates were obtained with duration (79%) and frequency (74%). These results suggest that an asymmetry in the speed of slow phase of the caloric nystagmus is the most relevant sign to proceed to X-ray examination, especially if found in cases where the residual hearing does not allow reliable audiometric results.

Adult↗
PubMed1984

Auditory brain-stem response and hearing threshold in cerebellopontine angle tumours.

The auditory brain-stem responses (ABR) in 19 patients with confirmed cerebellopontine angle tumours are evaluated in relation to the hearing threshold as obtained by pure-tone audiometry. ABR pathological alterations, in terms of either absence or presence of components, appear to relate to the suprathreshold stimulus intensity and to match the changes which can be observed in subjects with normal hearing, when stimulated at the equivalent suprathreshold intensity. Of the diagnostic indexes considered (I-V interval, IT5, delta V), IT5 and delta V could be evaluated in the largest patient population. They may be used in combination to enhance their sensitivity in retrocochlear lesion detection.

Audiometry↗
PubMed1984

Simultaneous recording of auditory evoked potentials. Relationships among the fast, middle and long latency components.

The whole pattern of the fast, middle and long latency auditory evoked potentials (AEP) was recorded simultaneously from the scalp surface of 13 normal-hearing adults. The individual responses were displayed on a nonlinear time axis in order to improve identification of the components. Stimulation consisted of 2048 unfiltered clicks, delivered monaurally at 80, 60, 40 dB HL with an ISI of 750 ms. Changes in mean latency and amplitude of each AEP component were statistically evaluated in relation to intensity and electrode montage (vertex-mastoid ipsi- and contralateral to the stimulated ear). The latencies of fast components I-VI and the slow P1 increase significantly with declining stimulus intensity. The amplitudes of the fast, I, II, III, V and the slow P1-N1, P2-N2 decrease significantly with intensity. As regards differences due to the electrode montage the contralateral recording causes significant changes in latency of the fast potentials up to wave IV, and changes in amplitude of the fast up to wave V, and of the slow P1-N1 and P2-N2. Therefore, as their latency and amplitude seem to be less closely related to the stimulus and electrode placement, the middle components behave differently, compared with the preceding and following components. Based on parametric comparisons of potentials ranging widely in latency, but each one evoked by an equal sensory input, this kind of AEP evaluation may be useful both for neurophysiological and clinical studies of the whole auditory pathway function.

Adult↗
PubMed1983

Electrocochleography and brainstem potentials in the diagnosis of the deaf child.

The deaf child must receive sound amplification before he reaches the age of two years. At this age the hearing threshold is best measured objectively by electrocochleography (ECochG) and auditory brainstem response (ABR) audiometry. When used correctly, both methods allow an exact threshold estimation which is informative enough for adequate hearing aid prescription. Both methods have advantages and disadvantages when used in children. The advantages of ECochG are: (a) a more exact threshold estimation and (b) strictly monaural evaluation. The advantages of ABR are: (a) ease of performance; it is not invasive and does not require general anaesthesia and (b) allows for exploration of higher levels in the auditory pathway up to the midbrain. We believe that ECochG and ABR are compatible and complementary in the diagnosis of childhood deafness. ABR could be used in first instance, while ECochG could be reserved for doubtful cases and for those who cannot be adequately sedated. Extra-audiological factors such as the availability of anaesthetists and varying hospital facilities, play a further role in determining the choice of electric response technique.

Audiometry↗
PubMed1983

Evaluation of the monaurally evoked brainstem response in the diagnosis of sensorineural hearing loss.

The auditory brainstem responses (ABRs) obtained in 47 subjects with asymmetric hearing loss (12 with surgically confirmed cerebello-pontine angle tumours, 35 without otoneurologic and/or neuroradiologic evidence of tumour) were evaluated by means of an index named delta V. The calculation of this index was based upon the patient's wave V absolute latency obtained at a fixed intensity of 90 dB HL and the value of latency predictable by means of the normative data. The index clearly separates retrocochlear from cochlear sites of lesion. Moreover delta V values obtained in defined cochlear lesions show a linear relation with the patient's pure tone hearing loss at 2 and 4 kHz; this behaviour is probably due to a reduction of the auditory dynamic range in the recruiting ears. delta V appears to have clinical usefulness because of two main points: first it is based upon an evaluation of the monaurally evoked ABR; second, it improves the diagnostic specificity of the responses. The rate of false positive results can be further reduced by combining delta V and IT5 values.

Audiometry, Evoked Response↗
PubMed1982

Clinical and audiological findings in a case of auditory agnosia.

A case is reported of severe agnosia for verbal and non-verbal sounds without associated aphasic disorder. A CT scan revealed bilateral, temporal lobe lesions from two ischaemic accidents that had occurred 9 months apart. The search for subtle deficits in the patient showed normal sensitivity to changes in the intensity and frequency of simple sounds; in contrast, his ability to discriminate sound duration and musical note sequences was severely impaired. The simultaneous recording of the whole auditory-evoked response pattern revealed no abnormality in the early components, which reflect the activation of the auditory nuclei and pathways of the brain stem. However, the middle and late components were delayed and slowed. These results and others in the literature suggest that the neocortex in man, as in other mammals, plays an essential role in the temporal aspects of hearing. Also, the two main ingredients commonly recognized in auditory agnosia, i.e. word deafness and the inability to interpret non-verbal sounds, are caused by the disruption of elementary, bilaterally represented cortical functions which start the processing of every kind of auditory information.

Agnosia↗
PubMed1982

Logarithmic display of auditory evoked potentials.

Auditory evoked potentials (AEP) can be simultaneously recorded on-line as a succession of 11 waves, through a single input channel of a mini-computer. Since the response waves differ widely in frequency, a computing routine has been developed to display the whole response pattern in a single picture. Based upon a non-linear samples reduction of the digitized response, this routine allows a logarithmic transformation of the time axis. The method improves the identification of the AEP components and provides an objective estimate of the central auditory pathway for both neurophysiological and neuroclinical studies.

Computers↗
PubMed1981

Habituation and rate effect in the auditory cortical potentials evoked by trains of stimuli.

The effects of the stimulus repetition rate over the habituated auditory cortical evoked responses were studied. The stimulation pattern consisted of trains of pure tone bursts with interstimulus interval (ISI) of 1 s, and intertrain interval (ITI) of 5 s, delivered with constant time and intensity parameters during 93 min. The analysis of the responses was based upon across averaging of the trains, each single response being evaluated in the latency and amplitude parameters. Two time-dependent factors affected the responses in a distinct way: the habituation throughout the whole stimulation and the rate effect within the train. The linear regressions of the time/amplitude functions of the responses were calculated in relation to the duration of ISI and ITI. By introducing a correction factor depending on the repetition rate it was possible to evaluate the relationships between habituation and repetition rate. Changes in the repetition rate do not have any effect on the habituation process. The two phenomena are completely distinct, and they probably have neurophysiologic substances corresponding to different levels in the central nervous system (CNS).

Acoustic Stimulation↗
PubMed1981

The auditory brainstem response to binaural delayed stimuli in man.

The brainstem responses (BER) evoked by binaural clicks (0.1 ms) with interaural time differences (delta t) from 0 to 3.5 ms were studied in 6 normal subjects. The responses analysis was carried out via computer in two different ways: (a) Comparison between binaural BER and templates obtained with the addition of two monaural BERs. (b) Extraction from the binaural BER of the second delayed pattern. The results suggest that an algebraic addition of the responses from the two stimulated sides is the main mechanism of the binaural BER generation. In comparison with the templates, the binaural response shows some differences which are evident at delta t = 0--1.5 ms and are limited in the region of VI and VII waves. Such differences are caused essentially to an amplitude decrease of the second pattern--that is response to the delayed stimulus--mainly at delta t 1.5 ms. However these results do not allow us to say if the phenomenon recorded at the surface is due to central adaptation or to specific mechanism of binaural interaction.

Acoustic Stimulation↗
PubMedDate not supplied

Clinical applicability of transient evoked otoacoustic emissions: identification and classification of hearing loss.

The study aimed at the development of a clinically applicable methodology that could: (1) discriminate transient evoked otoacoustic emission (TEOAE) recordings from normal hearing or hearing impaired individuals; (2) classify the nature of the hearing loss as conductive or as cochlear, and (3) define clear-cut TEOAE clinical criteria. A classification algorithm based on a multivariate discriminant analysis of fast Fourier transform data from recordings evoked by click stimuli of 50 +/- 2, 62 +/- 2, 68 +/- 2 and 80 +/- 2 dB SPL was used to discriminate 302 normal subjects from 383 subjects suffering from mild to moderate hearing losses. The best discriminant model (QDF80) produced a sensitivity of 93.8% and a specificity of 79.4%. When extra correlation criteria were serially applied to the classification outcome, the specificity was increased to 85.3%, but the sensitivity was marginally decreased to 91.7%. The classification of the correctly identified hearing-impaired cases yielded 93.8% identification of conductive and 75.1% identification of cochlear cases. A sensitivity analysis of the misclassified hearing-impaired cases suggested that the TEOAE spectra are well correlated with the 2-kHz but poorly correlated with the 4-kHz octave frequency.

Acoustic Stimulation↗
PubMedDate not supplied

The behaviour of wave V latency in cochlear hearing loss.

The audiological approach to the early diagnosis of cerebellopontine angle tumours (APC) is based mainly on ABR. In present work, wave V latency has been studied in two groups of patients: 308 cochlear cases and 74 retrocochlear cases (APC surgically confirmed tumours), in order to increase the sensitivity and specificity of the diagnostic indexes I-V, IT5 and Delta V. Wave V latencies have been evaluated in relation to hearing loss at 2-4 kHz and audiometric profile. Both these factors show a highly significant positive correlation with the latency, which consequently increases proportionally to hearing loss and high-frequency audiometric loss. A multiple regression analysis was therefore used to analyse the effects from the two variables, and a correction factor was calculated to compensate the latency values for hearing loss and threshold configuration. The effects of such a correction on the clinical results consist mainly of a reduction in the rate of cochlear false-negative results, which corresponds to improving the ABR specificity.

Audiometry, Evoked Response↗