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Results for “Auditory Threshold”

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At least 145 records · Page 8Linked to original sources
PubMed1994

Improvement in sensorineural auditory threshold of the guinea-pig fetus following delivery.

The human fetus in utero is hypoxic relative to the neonate due to differences between placental and pulmonary oxygenation. Comparable degrees of hypoxia induced in young and adult animals caused an elevation in hearing threshold of a sensorineural nature. It was hypothesised therefore that the human fetus may also have such an elevation of threshold. This was tested in this study by recording ABR thresholds to bone conducted stimuli in fetal guinea-pigs that were near full term and again in the same animals, after delivery and consequent pulmonary oxygenation. In every animal studied (n = 9), the neonatal threshold was better than that in the fetus. In those fetuses in which a response could be recorded (n = 5), the neonatal threshold was on average 20 dB better than in the fetus. These findings are probably due to a depression of the endocochlear potential induced by the relatively hypoxic state of the fetus. The hypoxic state would lead to a reduced transduction current in the hair cells in response to a stimulus and an elevated hearing threshold. At birth, with the shift to pulmonary oxygenation, the neonate becomes normoxic, the endocochlear potential rapidly reaches near maximal levels and threshold is improved.

Animals↗
PubMed1960

Auditory thresholds in the rat measured by an operant technique.

An adaptation of the Ratliff and Blough technique has been developed for auditory measurement in rats. Thresholds for a 2000-cy/sec tone were determined over a period of weeks. Kanamycin, an ototoxic agent, was then administered, and the gradual rise in threshold was followed.

Animals↗
PubMed1995

[The variation of the vestibular response vs. the variations of the auditory threshold after administration of glycerol in patients with Meniere's disease].

Vestibular and auditory functions after glycerol intake were assessed correlated in twenty-eight patients diagnosed as menieric according to AAOO criteria. All patients had unilateral Ménière's disease confirmed by monolateral hypoacusia and labyrinthine hypofunction. Hearing thresholds were tested by tone-audiometry, according to the standard glycerol test. Variation in vestibular response were assessed comparing the VOR during the rotatory sinusoidal test as well as the caloric test, before glycerol intake and 2 hours after drug administration. Slow phase angolar velocity, directional preponderance percentile and percentile variation between basic and control observation were calculated. The audiometric glycerol test was positive in 58% of the cases. The vestibular glycerol test was positive in 30% of the cases and no correlation between and individual results hearing threshold result was found. The findings reported by other Authors regarding auditory and vestibular responses to glycerol intake were verified. Possible reasons which may account for variation with regard to reaction patterns in the acoustic and non acoustic labyrinth after glycerin administration are discussed. In the Authors' view, incoherence between vestibular and cochlear response might be linked to differences in the physiology of the fluid in the two labyrinths. In the vestibular district, glycerol might induce an early depletive effect and a later paradoxal effects due to mechanical modification of the ampulla function.

Audiometry, Pure-Tone↗