Vowel confusion patterns in adults during initial 4 years of implant use.

This study investigated adult cochlear implant users' (n = 39) vowel recognition and confusions by an open-set syllable test during 4 years of implant use, in a prospective repeated-measures design. Subjects' responses were coded for phoneme errors and estimated by the generalized mixed model. Improvement in overall vowel recognition was highest during the first 6 months, showing statistically significant change until 4 years, especially for the mediocre performers. The best performers improved statistically significantly until 18 months. The poorest performers improved until 12 months and exhibited more vowel confusions. No differences were found in overall vowel recognition between Nucleus24M/24R and Med-ElC40+ device users (matched comparison), but certain vowels showed statistically significant differences. Vowel confusions between adjacent vowels were evident, probably due to the implant users' inability to discriminate formant frequencies. Vowel confusions were also dominated by vowels whose average F1 and/or F2 frequencies were higher than the target vowel, indicating a basalward shift in the confusions.

Effect of caffeine on simulator flight performance in sleep-deprived military pilot students.

Caffeine has been suggested to act as a countermeasure against fatigue in military operations. In this randomized, double-blind, placebo-controlled study, the effect of caffeine on simulator flight performance was examined in 13 military pilots during 37 hours of sleep deprivation. Each subject performed a flight mission in simulator four times. The subjects received either a placebo (six subjects) or 200 mg of caffeine (seven subjects) 1 hour before the simulated flights. A moderate 200 mg intake of caffeine was associated with higher axillary temperatures, but it did not affect subjectively assessed sleepiness. Flight performance was similar in both groups during the four rounds flown under sleep deprivation. However, subjective evaluation of overall flight performance in the caffeine group tended to be too optimistic, indicating a potential flight safety problem. Based on our results, we do not recommend using caffeine pills in military flight operations.

Changes in hearing aid use over the past 20 years.

The aim of this study was to find out how the use of hearing aids has been affected by the changes in hearing rehabilitation, hearing aids and society over the past 20 years. Seventy-six first-time hearing aid users were interviewed at their homes, and the results were compared with those of an earlier study made with the same method in 1983 in Finland involving both new and experienced hearing aid users. Hearing aid use and handling skills as well as satisfaction with the hearing aid were explored with interviews using the same questions in both studies. The number of first-time hearing aid users who did not use their hearing aids had decreased from 33.3% in 1983 to 5.3% at the present. Conversely, the number of regular users rose from 40.9 to 56.6%. The use of hearing aids was increased. The users were better able use their hearing aids and were more satisfied with them and the number of those who considered the counseling provided sufficient had also increased.

Temporary threshold shift in military pilots measured using conventional and extended high-frequency audiometry after one flight.

Noise of such a high level that it can result in hearing deterioration is an inherent characteristic of military flying. Susceptibility to hearing impairment was studied using 51 Finnish Air Force military personnel as subjects. The test persons flew missions on a British Aerospace Hawk 51 advanced jet trainer, Boeing F-18 Hornet, Mikoyan & Gurevich MiG-21bis and Saab 35 Draken interceptors, and a Valmet Redigo turboprop liaison aircraft. The duration of noise exposure was one flight mission, which varied from 30 to 60 min. Noise doses and levels were measured using a miniature microphone at the inlet of the ear canal, while a second microphone was located at the level of the subject's shoulder. Hearing thresholds were measured before each flight using conventional (0.125-8 kHz) and extended high-frequency (EHF) (8.20 kHz) audiometry. The measurements were repeated as soon as possible after the flight. The study showed that the pre-flight threshold levels of the subjects were good. Both conventional and EHF audiometry revealed statistically significant temporary threshold shifts (TTS) at several frequencies and with all aircraft types involved. The changes were, however, minor. The risk of noise-induced hearing impairment at the studied exposure levels is, in all probability, rather small. The role of extended high-frequency audiometry would be in research, and it might be performed for flying personnel upon entering service and every fifth year thereafter.