New Middle Class in Confucian Asia: Its Socio-cultural Background and Socio-political Orientations in Comparative Perspective

Copyright (c) Center of Excellence-Contemporary Asian Studie

A Role of Medial Olivocochlear Reflex as a Protection Mechanism from Noise-Induced Hearing Loss Revealed in Short-Practicing Violinists.

Previous studies have indicated that extended exposure to a high level of sound might increase the risk of hearing loss among professional symphony orchestra musicians. One of the major problems associated with musicians' hearing loss is difficulty in estimating its risk simply on the basis of the physical amount of exposure, i.e. the exposure level and duration. The aim of this study was to examine whether the measurement of the medial olivocochlear reflex (MOCR), which is assumed to protect the cochlear from acoustic damage, could enable us to assess the risk of hearing loss among musicians. To test this, we compared the MOCR strength and the hearing deterioration caused by one-hour instrument practice. The participants in the study were music university students who are majoring in the violin, whose left ear is exposed to intense violin sounds (broadband sounds containing a significant number of high-frequency components) during their regular instrument practice. Audiogram and click-evoked otoacoustic emissions (CEOAEs) were measured before and after a one-hour violin practice. There was a larger exposure to the left ear than to the right ear, and we observed a left-ear specific temporary threshold shift (TTS) after the violin practice. Left-ear CEOAEs decreased proportionally to the TTS. The exposure level, however, could not entirely explain the inter-individual variation in the TTS and the decrease in CEOAE. On the other hand, the MOCR strength could predict the size of the TTS and CEOAE decrease. Our findings imply that, among other factors, the MOCR is a promising measure for assessing the risk of hearing loss among musicians

Amount of hearing deterioration reflects exposure level.

<p>Correlation of exposure level at 4 kHz with the elevation of hearing threshold at 4 kHz (A) and with CEOAE decrease at 4 kHz (B). The data for the left and right ears are represented by the dots and crosses, respectively. The numbers attached to the symbols are participant numbers. The Pearson correlation coefficients, R, with their p-values shown in the panels, and the regression lines were derived for the pooled data for both ears.</p

Transient hearing deterioration caused by the short-duration violin practice.

<p>A: The audiogram of left ear (left panel) and right ear (right panel) before (blue line) and after (red line) the violin practice. B: The CEOAE spectrum of left ear (left panel) and right ear (right panel) before (blue line) and after (red line) the violin practice. Error bars show the standard errors across listeners. Significance of post-hoc pairwise comparisons is marked as *** <i>p</i><0.001 and * <i>p</i><0.05. The data obtained 60 minutes after the end of the violin practice are shown by gray dashed lines. <b>C</b>: Correlation between CEOAE decrease at 4 kHz and TTS at 4 kHz. Each participant’s data point is represented with participant number.</p

Acoustic characteristics during the violin practice.

<p>A: Typical characteristics of the acoustic exposure during a violin practice for the left ear. B: Comparison between exposure level for the left ear and right ear (* <i>p</i><0.0029, Bonferroni-corrected α).</p

MOCR strength could predict the size of hearing deterioration caused by a violin practice.

<p>Correlation of ipsilateral MOCR strength with the elevation of hearing threshold at 4 kHz (A) and with CEOAE decrease at 4 kHz in the left ear (B). Pearson correlation coefficients are shown with their p-value in parentheses. Regression lines were derived from linear least squares regression. Each participant’s data point is represented with participant number.</p

Electron-tracking Compton camera imaging of technetium-95m.

Imaging was conducted using an electron tracking-Compton camera (ETCC), which measures γ-rays with energies in the range of 200-900 keV from 95mTc. 95mTc was produced by the 95Mo(p, n)95mTc reaction on a 95Mo-enriched target. A method for recycling 95Mo-enriched molybdenum trioxide was employed, and the recycled yield of 95Mo was 70%-90%. Images were obtained with the gate of three energies. The results showed that the spatial resolution increases with increasing γ-ray energy, and suggested that the ETCC with high-energy γ-ray emitters such as 95mTc is useful for the medical imaging of deep tissue and organs in the human body