Aging changes in auditory discriminating and hearing thresholds

Measurements of auditory discriminating thresholds of frequency (Δf), phase (Δφ)and intensity (ΔI) of repetitive clicks and hearing thresholds (HT) of pure tones were performed in human subjects with no history of ear pathology the range of age being 17-67 years. The reference repetition rate of the clicks used was 500 pps and the frequencies for pure tone au-diometry were 500 Hz-8000Hz in octave steps. Aging changes of Δf, Δφ, ΔI and HT are obvious after the age of 40, while before 40; only Δφ, ΔI and HT of 8 kHz show mild but statistically significant increase with ape. Calculated on the basis of the 50 percentile curves from the experimental results (N=190), formulae of these aging changes can be expressed as:Δf = 0.0024X2 - 0.116X + 2.116 (pps), Δφ = 0.0010X2 - 0.050X + 1.343 (degrees), ΔI =0.0004X2 -0.016X+0.455 (dB) and, for 8000 Hz pure tone, HT = 0.0424X2 -2.15X+34.94 (dBnHL).

The comparison of auditory behavioral and evoked potential responses (steadystate and cortical) in subjects with occupational noise-induced hearing loss

Objective: To define difference scores between PTA, ASSR and CERA thresholds in subjects with occupational NIHL.Design: 44 subjects undergoing a medico-legal expert assessment for occupational NIHL and fulfillingcriteria of reliability were considered. Assessment included: PTA, 40 Hz binaural multiple ASSR and CERA(1-2-3 kHz).Results: The respective average difference scores (ASSR - PTA) for 1, 2 and 3 kHz are 13.01 (SD 10.19) dB,12.72 (SD 8.81) dB and 10.38 (SD 8.19) dB. The average (CERA - ASSR) difference scores are 1.25 (SD 14.63)dB for 1 kHz (NS), 2.73 (SD 13.03) dB for 2 kHz (NS) and 4.51 (SD 12.18) dB for 3 kHz. The correlationbetween PTA and ASSR (0.82) is significantly stronger than that between PTA and CERA (0.71). In a givensubject, PTA thresholds are nearly always lower (i.e., better) than ASSR thresholds, whatever the frequency (1-2-3 kHz) and the side (right e left). A significant negative correlation is found between thedifference score (ASSR e PTA) and the degree of hearing loss.Conclusion: ASSR outperforms CERA in a medicolegal context, although overestimating the behavioralthresholds by 10e13 dB.

Hearing characteristics of cephalopods: Modeling and environmental impact study

Cephalopods(octopus,squid and cuttlefish)are some of the most intriguing molluscs,and they represent economically important commercial marine species for fisheries.Previous studies have shown that cephalopods are sensitive to underwater particle motion,especially at low frequencies in the order of 10 Hz.The present paper deals with quantitative modeling of the statocyst system in three cephalopod species:Octopus vulgaris,Sepia officinalis and Loligo vulgaris.The octopus’s macula/statolith organ was modeled as a 2nd-order dynamic oscillator using parameter values estimated from scanning electron micrograph images.The modeling results agree reasonably well with experimental data(acceleration threshold)in the three cephalopod species.Insights made from quantitative modeling and simulating the particle motion sensing mechanism of cephalopods elucidated their underwater particle motion detection capabilities.Sensitivity to emerging environmental issues,such as low frequency noise caused by near-shore wind farms and increasing levels of carbon dioxide in the ocean,and sensitivity to sounds produced by impending landslides were investigated in octopus using the model.

SATURATION DIVING WITH HELIOX TO 350 METERS OBSERVATION ON HEARING THRESHOLD, BRAINSTEM EVOKED RESPONSE AND ACOUSTIC IMPEDANCE

Four divers were compressed to 350 m to observe changes in hearing threshold, brainstem evoked response and acoustic impedance. The divers experienced no tinnitus, impairment of bearing, earache daring compression. Examination showed that the threshold of tower frequency range of hearing was elevated because of the masking effect of the noise in the hyperbaric chamber. Changes in waveform and latency of brainstem evoked response were due to changes in sound wave transmission affected by the chamber pressure and a poor ratio of signal to noise in the hyperbaric environment with heliox. All these changes were transient After leaving the chamber, the hearing threshold and brainstem evoked response returned to normal. Besides, there were no changes in tympanogram, acoustic compliance and stapedius reflex before and after diving. This indicated the designed speed of compression and decompression in the experiment caused no damage to the divers' acoustic system, and the functions of their Eustachain tubes, middle and inner ears were normal during the diving test