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Results for “Auditory Threshold”

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PubMed2002

[The examinations of hearing in infants treated in neonatal intensive care units].

The aim of the study was the estimation of hearing and the analysis of the risk factors for hearing loss in infants treated in neonatal intensive care units. The examinations were performed in 287 infants, who we examined in ENT Department between the ages of three and six months after discharge from neonatal intensive care unit. The infants were investigated with the use of ABR elicited with clicks and tone burst of 500 and 1000 Hz. Elevated auditory thresholds were found in 48 neonates in the first examination and in 27 in the second examination. Among the risk factors we observed the most frequently: gestational age < 33 Hbd, birth weight < 1500 g, respiratory and cardiovascular disorders and intracranial haemorrhages.

Cardiovascular Diseases↗

PubMed2002

Pericranial muscular, respiratory, and heart rate components of the orienting response.

We have earlier found that voluntary attention to weak auditory stimuli induces inhibition of respiration, heart rate, and electromyographic (EMG) activity of masticatory and lower facial muscles and that these responses lower the auditory threshold for low-frequency sounds. In the current study, we examined whether this inhibitory response pattern also occurs during involuntary orienting to novel, nonsignal sounds. Environmental sounds of low intensity were presented unexpectedly during the performance of a reading task. Orienting responses (ORs) were elicited as indicated by heart rate deceleration and skin conductance responses. Inhibitory respiratory and pericranial EMG responses appeared to be intrinsic components of the OR. Together with the autonomic responses, they habituated when a nonsignal auditory stimulus was repeatedly presented. Our results also suggest that eye and pinna movements occurred toward the sound source. The results of the current study are consistent with the hypothesis of Sokolov (1963) that the primary function of the OR is enhancement of sensory sensitivity.

Acoustic Stimulation↗

PubMed1996

[Brainstem auditory evoked potentials in neonatology: the method and results in a group of normal newborns].

Brainstem evoked responses audiometry was performed on 10 newborn infants. They ranged in postnatal age from 19 hours to 5 days and in estimated gestational age from 39 to 42 weeks. Clicks of 0.1 msec duration were presented at a rate of 11.4 per second. Measurements were made at 50, 80 and 100 dB. Wave V latencies were evaluated at 50, 80 and 100 dB HL in order to measure the auditory threshold. The latency of wave V is the datum of interest. Wave V responses were obtained bilaterally at 50 dB HL. Waves I and III latencies were measured at 100 dB HL.

Acoustic Stimulation↗

PubMed1987

The effects of hypoxia on sensory cells of the cochlea in chinchilla.

The effects of hypoxia on the sensory epithelium of the cochlea were investigated in the chinchilla. Systemic hypoxia was produced by increasing the dead space of the respiratory tidal volume. A disarrangement of hair-cell stereocilia, and cytoplasmic protrusions from sensory cells are the main findings in cochleas from hypoxic animals; these changes take place firstly at the inner hair-cells then, with the increase in degree of hypoxia, at the outer hair-cells. These degenerative changes of sensory cells correlate well with both respiratory suppression and with the elevation of auditory threshold to click stimulation as monitored using the compound action potential recording from the cochlear nerve. The latter measure appears to be a useful indicator of cochlear hypoxia. Our morphological findings are similar to other studies including those which have reported on post-mortem cochlear hair-cell degeneration. Our studies indicate the deleterious effects of long term hypoxia on cochlear mechanisms and point to the need for careful monitoring of cardiovascular and respiratory functions in animals under anaesthesia for physiological studies of the auditory system.

Action Potentials↗

PubMed1998

[Distortion product otoacoustic emissions for the assessment of auditory sensitivity].

Distortion product otoacoustic emissions (DPOAEs) were evaluated in 494 normal and 506 cochlear-impaired human ears, to determine whether DPOAEs depend on factors such as background noise, the shape of the pure tone audiogram, sex and aging, and whether a DPOAE test can perform well in distinguishing normal-hearing from hearing-impaired ears. The amplitudes of DPOAEs were measured at the frequency of 2f1-f2 (f1 < f2, f2/f1 = 1.22, f2 at 1, 2 and 4 kHz) using as stimuli two pure tones at level of 70 dB from an ILO92 Otoacoustic Emission Analyzer. The correlation coefficients between the DPOAE level and the auditory threshold decreased as the background noise levels at 1 kHz and 2 kHz increased. Therefore, it appeared that ears with large background noise levels would be inadequate for the study of DPOAEs predicting the hearing state. The sensitivity (normal-hearing ears identified as normal hearing) and the specificity (hearing-impaired ears identified as hearing impaired) at the equal-sensitivity-specificity condition were 80.7-86.7% at 1, 2 and 4 kHz, and the areas under the receiver operating characteristic (ROC) curves, which were used to estimate the test performance, were 0.88 for 1 kHz, 0.91 for 2 kHz and 0.92 for 4 kHz. Since these results suggest that a DPOAE can be used as a reliable technique for objective auditory tests, it is thought that actual values (DPOAE level: 4.3 dB at 1 kHz, 5.0 dB at 2 kHz and 2.9 dB at 4 kHz) of false-positive (hearing-impaired ears identified as normal hearing) rates corresponding to 5% can be used in clinical evaluation to separate normal hearing from hearing-impaired ears. There was, however, a significant age effect at 4 kHz on DPOAEs in the ears with the same pure tone hearing thresholds, and the areas of the ROC curves in subjects ranging from 10 to 29 years old were larger than in subjects over 50 years (1 kHz: 0.88 to 0.94 versus 0.83 to 0.84, 2 kHz: 0.95 versus 0.89, 4 kHz: 0.95 to 0.96 versus 0.88 to 0.89). Therefore, it is thought that age-adjusted norms may be necessary for the accurate interpretation of DPOAE results.

Adolescent↗

PubMed1983

[Recovery process of auditory perceptual disorders in a child with word deafness].

The patient was a right-handed boy. Pregnancy and delivery were normal. There were no neonatal complications. His development was normal until the age of 6 years and 10 months when he suddenly fell into coma. He was admitted to a hospital, where he was diagnosed as having encephalopathy of unknown cause. It was found that he did not respond to verbal stimuli after recovery from coma. He was referred to our hospital for detailed examination of hearing at the age of 7 years, and received neuroradiological and audiological examinations including X-ray CT, positron-CT, behavioral audiometry, auditory evoked response audiometry as well as other hearing and speech tests. Pure tone audiometry showed that auditory thresholds for pure tones ranging from 125 to 8,000 Hz were normal, while speech audiometry demonstrated that he was unable to discriminate test words. However, he accurately recognized environmental sounds and noises as well as sounds produced by musical instruments. The decreased uptake of 11C-glucose at the left temporal lobe was demonstrated by positron CT, although no abnormality was showed by X-ray CT. WISC-R showed he had normal intelligence. ITPA demonstrated that the psycholinguistic ability via visual channel remained intact, whereas auditory memory and auditory closure were markedly impaired. The boy had no difficulties in reading, naming and writing. Speech therapy was started as soon as diagnosis of word deafness was made. Until 6 months after onset, he never understood and repeated what was said to him.(ABSTRACT TRUNCATED AT 250 WORDS)

Aphasia↗

PubMed1998

The value of methylprednisolone in the treatment of an experimental sensorineural hearing loss following drill-induced ossicular chain injury: a randomized, blinded study in guinea-pigs.

In a previously established animal model a standardized drill-induced injury to the body of the incus was applied, and the effects on hearing were characterized by electrocochleography. In a placebo-controlled, randomized, blinded study methylprednisolone showed no protective effect in reducing or improving the auditory threshold shifts, which occurred within seconds after drilling and remained stable throughout the 5-week observation period. Therefore the otologic surgeon must pay close attention to avoiding any contact of a rotating burr with an ossicle in an intact ossicular chain.

Animals↗

PubMed2006

Effects of exposing gonadectomized and intact C57BL/6J mice to a high-frequency augmented acoustic environment: Auditory brainstem response thresholds and cytocochleograms.

Gonadectomized and surgically intact adult C57BL/6J (B6) mice of both sexes were exposed for 12h nightly to a high-frequency augmented acoustic environment (AAE): repetitive bursts of a half-octave noise band centered at 20 kHz, 70 dB SPL. The effects of sex, gonadectomy, and AAE treatment on genetic progressive hearing loss (exhibited by B6 mice) were evaluated by obtaining auditory brainstem response thresholds at ages 3-, 6-, and 9-months; hair cell counts (cytocochleograms) were obtained at 9 months. A sex difference in the rate of genetic progressive hearing loss in B6 mice (observed by earlier studies) was confirmed, with females exhibiting a faster rate of threshold elevations and more severe loss of hair cells at age 9 months. Gonadectomy had no consistent effects on the rate or severity of hearing loss in non-exposed mice of either sex. An unexpected finding was that the high-frequency AAE treatment caused additional ABR threshold elevations and hair cell loss. In an earlier study, the same high-frequency AAE treatment on DBA/2J mice ameliorated hearing loss. The most severe AAE-induced losses occurred in surgically intact females, suggesting a potentiating effect of ovarian hormone(s).

Acoustic Stimulation↗

PubMed1981

Effects of neonatal thyroxine, genotype, and noise on the ear and audiogenic seizures.

Seyfried, Glasser, and Yu recently reported that the DBA/2J mouse genotype, which is innately susceptible to audiogenic seizures, has high neonatal levels of thyroxine (T4) and that neonatal injections of T4 induce susceptibility in the C57BL/6J mouse. In the C57BL/6J mouse, neonatal T4 injections produced a temporary peripheral auditory dysfunction which appeared to be conductive in nature. A cochlear dysfunction was also seen in the DBA/2J mouse and in the acoustically primed C57BL/6J mouse. Since a peripheral auditory threshold elevation in these latter groups of mice appears to be causally related to their susceptibility to audiogenic seizures, it is likely that at least a portion of the susceptibility that Seyfried et al. reported was due to the effects of T4 on the ear.

Acoustic Stimulation↗

PubMed2006

Effect of attentional state on frequency discrimination: a comparison of children with ADHD on and off medication.

Debate continues over the hypothesis that children with language or literacy difficulties have a genuine auditory processing deficit. Several recent studies have reported deficits in frequency discrimination (FD), but it is unclear whether these are genuine perceptual impairments or reflective of the comorbid attentional problems that exist in many children with language and literacy difficulties. The present study investigated FD in children with attention deficit hyperactivity disorder (ADHD) when their attentional state was altered with stimulant medication. Auditory thresholds were obtained using FD and frequency modulation detection (FM) tasks. In the FD task, participants judged which of 2 pairs contained a high-low frequency sound, and in the FM task, children judged which of two tones "wobbled" (i.e., modulated). Children with ADHD had significantly poorer and more variable FD performance when off compared to on stimulant medication, and did significantly worse than controls on all FD runs when off but not on stimulant medication. However, children with ADHD did not differ from controls on the FM task. These findings demonstrate that certain auditory discrimination tasks are influenced by the child's attentional status. In addition, significant relationships between FD and measures of language and reading were abolished when comorbid attentional difficulties were taken into account. The study has implications for design and interpretation of studies investigating links between auditory discrimination and difficulties in language and literacy.

Age Factors↗

PubMed1998

The auditory brainstem response of aged guinea pigs.

The auditory brainstem response (ABR) technique was used to investigate potential dysfunctions in the auditory brainstem of the pigmented guinea pig (Cavia porcellus) associated with biological ageing. Animals aged from 58 days to 4 years 3 months were tested. ABRs were recorded at stimulation intensities from 85 dB HL to -10 dB HL. The auditory thresholds were found to undergo marked elevations in old animals, by an average of 32 dB. From the traces obtained, four positive deflection waves were reliably recorded. The latency of each of the four waves was evaluated at different stimulation intensities in guinea pigs of different ages. Although there was a trend for the latencies to increase in old age, these differences were not statistically significant. Similarly, there were no significant age-related changes in the inter-peak intervals. The latency/intensity functions of the four waves produced parallel curves. However, the curve from the old age group was shifted to the right, by an average of 35 dB, indicative of conductive hearing loss. There was no evidence of retro-cochlear hearing loss. Therefore, it appears that the threshold elevations in the old animals can be accounted for by conductive hearing loss, presumably in the middle ear. In 24% of the old animals tested, no ABR could be elicited. It would appear that these animals had suffered severe sensorineural hearing loss.

Aging↗

PubMed1998

[The effect of white noise on activity of nitric oxide synthase in cochlear nuclei of guinea pigs].

This experiment adopted lipoic amido dehydrogenase (NADPH-d) histochemistry method and image pattern analysis technique to investigate the relationship between nitric oxide synthase (NOS) neurons and activity of NOS and auditory threshold, and to explore the possible role of NOS neurone in cochlear nuclei of guinea pigs after exposed to white noise. The results showed that the quantity and staining intensity of positive NOS neurons in cochlear nuclei increased obviously after exposed to noise. It reached the peak 2 weeks later and remained high expression during 3-4 weeks. It restored 5 weeks later but was still higher than normal. Within 7 days after exposed to noise, activity of NOS in cochlear nuclei deviated from ABR threshold. After 7 days, activity of NOS had a positive correlation with ABR threshold (r = 0.9571, P < 0.01). It is suggested that NOS in cochlear nuclei might play double role after exposed to white noise. On one hand, a certain range of activity of NOS might help to restore injured neurons. On the other hand, over expression of NOS might exacerbate the injury of cochlear nerves.

Animals↗

PubMed1982

[Effect of wide-band modulated electromagnetic fields on the workers of high-frequency telephone exchanges].

Physiological examinations of 63 subjects were performed as well as clinical, functional, paraclinical, etc. examinations of 82 subjects working under the effect of wide-band modulated electromagnetic fields in HFA of telephone exchanges. Some physiological changes were found as regards the level of blood pressure and auditory threshold. Though the intensity of EMF were within the allowable limits, changes in the neuro-vegetological state, genital sphere, were found in some of the examined workers as well as in immunologic reactivity and some paraclinical indices, described to develop under electromagnetic effect, attributed to the specificity of EMF-wide-band, modulated.

Adult↗

PubMed1997

[Effect of white noise on activity and gene expression of nitric oxide synthase in cochlear nuclei of guinea pigs].

NADPH-diaphorase (NADPH-d) histochemistry method and semiquantitative polymerase chain reaction (PCR) technology were adopted to study nitric oxide synthase (NOS) neurons and to investigate the content change of NOS mRNA and the relationship between it and auditory threshold and to explore the possible role of NOS neurons in cochlear nuclei of guinea pigs after exposed to white noise. The results showed that the quantity and staining intensity of positive NOS neurons in cochlear nuclei increased obviously after exposed to noise. It reached the peak 2 week later and remained 5 week than normal. The regulation of NOS mRNA was consistent with that of morphological observation. NOS mRNA content in 2 w group was the highest and was 4.02 times higher than normal. After exposed to noise, ABR threshold shift was in positive correlation with NOS mRNA content in cochlear nuclei (r = 0.9655, P < 0.01). It is suggested that positive NOS neurons in cochlear nuclei might be involved in controlling injury and repair of cochlear nerves. The high expression of NOS gene might be an important factor in pathogenic mechanism of noise deafness.

Animals↗

PubMed1984

Hemispheric imbalances in schizophrenia.

Evidence is presented of two syndromes in schizophrenia distinguished by opposite asymmetries in hemispheric activation. A florid syndrome is coincidental with left hemisphere overactivation and a non-florid syndrome with right hemispheric overactivation. In each case underactivation characterizes the opposite hemisphere. While this was first revealed by electrodermal lateral asymmetries, a review of the literature provides support from other measures of dynamic process asymmetries such as arousal and attention, and includes electrocortical activity in the form of EEG activity and evoked potentials (EP), the Hoffman reflex, lateral eye movements, auditory thresholds, dichotic listening, somatosensory extinction and handedness. A preliminary empirical test of the model involving a spectral analysis of EPs recorded from occipital and temporal placements was also confirmatory. While hemispheric imbalance may result from asymmetries in fixed structural processes the imbalance itself determines the form the psychosis follows which, due to the dynamic nature of the neuropsychological process, is presumably modifiable.

Arousal↗

PubMed1997

Bat-deafness in day-flying moths (Lepidoptera, Notodontidae, Dioptinae).

Assuming that bat-detection is the primary function of moth ears, the ears of moths that are no longer exposed to bats should be deaf to echolocation call frequencies. To test this, we compared the auditory threshold curves of 7 species of Venezuelan day-flying moths (Notodontidae: Dioptinae) to those of 12 sympatric species of nocturnal moths (Notodontidae: Dudusinae, Noctuidae and Arctiidae). Whereas 2 dioptines (Josia turgida, Zunacetha annulata) revealed normal ears, 2 (J. radians, J. gopala) had reduced hearing at bat-specific frequencies (20-80 kHz) and the remaining 3 (Thirmida discinota, Polypoetes circumfumata and Xenorma cytheris) revealed pronounced to complete levels of high-frequency deafness. Although the bat-deaf ears of dioptines could function in other purposes (e.g., social communication), the poor sensitivities of these species even at their best frequencies suggest that these moths represent a state of advanced auditory degeneration brought about by their diurnal life history. The phylogeny of the Notodontidae further suggests that this deafness is a derived (apomorphic) condition and not a retention of a primitive (pleisiomorphic), insensitive state.

Acoustic Stimulation↗

PubMed2003

[Hearing evaluation in patients suffering from hypercholesterolemia].

The negative influence of hypercholesterolemia on the blood vessels condition and following degeneration lesions of the organs is well known. The aim of our study was to estimate the lipid balance disorders influence on the small blood vessels of the brain and inner ear in the patients with hypercholesterolemia and hypertriglyceridemia on the base of the audiometric, ABR and TEOAE evaluations. In our study we observed no statistical significant differences between the mean auditory thresholds in the study and control groups as well as statistical negative correlation between cholesterol serum level and amplitudes of TEOAE. In the ABR evaluation we stated the prolonged latency of the wave III and V as well as I-III and III-V interpeaklatencies in the patients with hyperlipidemia in comparison with the control group.

Adult↗

PubMed1994

Neonatal auditory brainstem response thresholds to air- and bone-conducted clicks: 0 to 96 hours postpartum.

Auditory brainstem response (ABR) thresholds to air- and bone-conducted clicks were investigated in 40 full-term neonates. Subjects were divided into two groups of 20 according to postpartum age: less than 48 hours and between 49 and 96 hours. Mean ABR thresholds to air- and bone-conducted clicks for neonates less than 48 hours postpartum were 14.5 dB nHL (51.5 dB peak SPL) and 1.8 dB nHL (36.8 peak re: 1 microN), respectively, while those for neonates between 49 and 96 hours were 3.8 dB nHL (40.8 dB peak SPL) and 1.5 dB nHL (36.5 dB peak re: 1 microN), respectively. A significant difference was found between the two group mean ABR thresholds to air-conducted stimuli (p < .0001) but not for the bone-conducted stimuli (p < .8959). A statistically significant within-group difference was found between the ABR thresholds to air- and bone-conducted stimuli for only the neonates less than 48 hours of age (p < .0001). When the data was collapsed across groups, simple linear regression analyses revealed a statistically significant relation between postpartum age and ABR threshold to air-conducted stimuli (p < .0001) and a nonsignificant relation between postpartum age and ABR threshold to bone-conducted stimuli (p < .9744). These findings support the notion that some resolution of fluids and residuals in the middle ear occurs during the first 48 hours postpartum and that air-conducted stimuli are attenuated during that period. As such, a physiologic conductive deficit among the younger neonates is suggested.

Acoustic Stimulation↗