Although sound exposure from personal listening devices (PLDs) could potentially lead to noise-induced hearing loss (NIHL), the actual hearing risk associated with the use of these devices is still unclear. In this study, early hearing effects related to PLD usage were evaluated in 35 young adult PLD users (listening for >1 h/day, at >50% of the maximum volume setting of their devices) and their age- and sex-matched controls using a combination of conventional and extended high-frequency audiometry as well as transient-evoked otoacoustic emission (TEOAE) and distortion product of otoacoustic emission (DPOAE) measurements. The mean listening duration of the PLD users was 2.7 ± 1.0 h/day while their estimated average listening volume was 81.3 ± 9.0 dBA (free-field corrected). Typical signs of NIHL were not detected in the audiogram of PLD users and their audiometric thresholds at most of the conventional test frequencies (0.25-8 kHz) were comparable with those obtained from controls. However, compared with the controls, mean hearing thresholds of PLD users at many of the extended high-frequencies (9-16 kHz) were significantly higher. In addition, TEOAE and DPOAE amplitudes in users were reduced compared with controls. The deterioration of extended high-frequency thresholds and the decrease in DPOAE amplitudes were more evident in the users' right ears. These results indicate the presence of an early stage of hearing damage in the PLD user group. Preventive steps should be taken as the initial hearing damage in these users could eventually progress into permanent NIHL after many years of PLD use.

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Educators in medical schools around the world are presently experimenting with innovative ways of using web-based learning to supplement the existing teaching and learning process. We have recently used a popular open-source course management system (CMS) called the modular object-oriented dynamic learning environment (Moodle) to construct an online site (DPhysiol) to facilitate our face-to-face teaching of physiology to a group of first-year students in the Bachelor of Medicine and Bachelor of Surgery program. The integration of the Moodle site into our teaching was assessed using online log activity, student examination marks, and feedback from students. The freely available Moodle platform was simple to use, helped to effectively deliver course materials, and has features that allowed cooperative learning. Students who used the CMS throughout their academic year and commented favorably regarding its use as a complement to the face-to-face classroom sessions. The group of students used the CMS obtained significantly higher scores in the final examination compared with the previous class that did not use the CMS. In addition, there was a significant correlation between student participation and performance in online quizzes and their final examination marks. However, students' overall online usage of the CMS did not correlate with their examination marks. We recommend Moodle as a useful tool for physiology educators who are interested in integrating web-based learning into their existing teaching curriculum.

OBJECTIVE:The usage of personal listening devices (PLDs) is associated with risks of hearing loss. The aim of this study is to evaluate the effects of music exposure from these devices on high-frequency hearing thresholds of PLD users. MATERIALS and METHODS:A total of 282 young adults were questioned regarding their listening habits and symptoms associated with PLD listening. Their audiogram thresholds were determined at high (3-8 kHz) frequencies and extended high frequencies (EHFs, 9-16 kHz). The preferred listening volumes of PLD users were used to compute their overall 8-h equivalent music exposure levels (L Aeq8h ). RESULTS:Approximately 80% of the subjects were regular PLD users. Of these, 20.1% had L Aeq8h of ≥75 dBA, while 4.4% of them had L Aeq8h of ≥85 dBA, which carries a high risk of hearing damage. Compared with those exposed to L Aeq8h of <75 dBA, subjects who had L Aeq8h of ≥75 dBA reported a significantly higher incidence of tinnitus and difficulty in hearing others immediately after using PLDs. PLD users who were exposed to L Aeq8h of ≥75 dBA and had been using their devices for ≥4 years also showed significantly higher mean audiogram thresholds compared with non-users at most EHFs tested. In addition, the thresholds of PLD users at EHFs showed a weak but significant positive correlation with their L Aeq8h . CONCLUSION:The present findings suggest that excessive exposure to music among PLD users may lead to initial effects on their hearing at very high frequencies.

Animal models have demonstrated that mild hearing loss caused by acoustic trauma results in spontaneous hyperactivity in the central auditory pathways. This hyperactivity has been hypothesized to be involved in the generation of tinnitus, a phantom auditory sensation. We have recently shown that such hyperactivity, recorded in the inferior colliculus, is still dependent on cochlear neural output for some time after recovery (up to 6 weeks). We have now studied the capacity of an intrinsic efferent system, i.e., the olivocochlear system, to alter hyperactivity. This system is known to modulate cochlear neural output. Anesthetized guinea pigs were exposed to a loud sound and after 2 or 3 weeks of recovery, single-neuron recordings in inferior colliculus were made to confirm hyperactivity. Olivocochlear axons were electrically stimulated and effects on cochlear neural output and on highly spontaneous neurons in inferior colliculus were assessed. Olivocochlear stimulation suppressed spontaneous hyperactivity in the inferior colliculus. This result is in agreement with our earlier finding that hyperactivity can be modulated by altering cochlear neural output. Interestingly, the central suppression was generally much larger and longer lasting than reported previously for primary afferents. Blockade of the intracochlear effects of olivocochlear system activation eliminated some but not all of the effects observed on spontaneous activity, suggesting also a central component to the effects of stimulation. More research is needed to investigate whether these central effects of olivocochlear efferent stimulation are due to central intrinsic circuitry or to coactivation of central efferent collaterals to the cochlear nucleus.