Einfluss exogener Faktoren auf Altersschwerhörigkeit

The sensory substrate of multimodal communication in brown-headed cowbirds: are females sensory 'specialists' or 'generalists'?

Many animals communicate with multimodal signals. While we have an understanding of multimodal signal production, we know relatively less about receiver filtering of multimodal signals and whether filtering capacity in one modality influences filtering in a second modality. Most multimodal signals contain a temporal element, such as change in frequency over time or a dynamic visual display. We examined the relationship in temporal resolution across two modalities to test whether females are (1) sensory 'specialists', where a trade-off exists between the sensory modalities, (2) sensory 'generalists', where a positive relationship exists between the modalities, or (3) whether no relationship exists between modalities. We used female brown-headed cowbirds (Molothrus ater) to investigate this question as males court females with an audiovisual display. We found a significant positive relationship between female visual and auditory temporal resolution, suggesting that females are sensory 'generalists'. Females appear to resolve information well across multiple modalities, which may select for males that signal their quality similarly across modalities.

Cigarette smoking causes hearing impairment among Bangladeshi population

Lifestyle including smoking, noise exposure with MP3 player and drinking alcohol are considered as risk factors for affecting hearing synergistically. However, little is known about the association of cigarette smoking with hearing impairment among subjects who carry a lifestyle without using MP3 player and drinking alcohol. We showed here the influence of smoking on hearing among Bangladeshi subjects who maintain a lifestyle devoid of using MP3 player and drinking alcohol. A total of 184 subjects (smokers: 90; non-smokers: 94) were included considering their duration and frequency of smoking for conducting this study. The mean hearing thresholds of non-smoker subjects at 1, 4, 8 and 12 kHz frequencies were 5.63±2.10, 8.56±5.75, 21.06±11.06, 40.79±20.36 decibel (dB), respectively and that of the smokers were 7±3.8, 13.27±8.4, 30.66±12.50 and 56.88±21.58 dB, respectively. The hearing thresholds of the smokers at 4, 8 and 12 kHz frequencies were significantly (p<0.05) higher than those of the non-smokers, while no significant differences were observed at 1 kHz frequency. We also observed no significant difference in auditory thresholds among smoker subgroups based on smoking frequency. In contrast, subjects smoked for longer duration (>5 years) showed higher level of auditory threshold (62.16±19.87 dB) at 12 kHz frequency compared with that (41.52±19.21 dB) of the subjects smoked for 1-5 years and the difference in auditory thresholds was statistically significant (p<0.0002). In this study, the Brinkman Index (BI) of smokers was from 6 to 440 and the adjusted odds ratio showed a positive correlation between hearing loss and smoking when adjusted for age and body mass index (BMI). In addition, age, but not BMI, also played positive role on hearing impairment at all frequencies. Thus, these findings suggested that cigarette smoking affects hearing level at all the frequencies tested but most significantly at extra higher frequencies.

[Hearing impairment and dementia]

The World Health Organization (WHO) burden of disease study identified dementia and hearing problems as leading causes of loss of quality of life in the industrial world. The prevalence of dementia and hearing problems increases in aging societies. Comorbidity of these two diseases causes increasing demands on healthcare systems. The similarity and possible interaction of symptoms renders diagnosis and therapy of dementia and hearing loss a challenge for neurologists, psychiatrists, ear, nose and throat (ENT) and hearing specialists. Knowledge of both diseases enables an early intervention and helps preserve participation in society and thereby reducing the risk of developing dementia. This paper focuses on the characteristics of the diagnosis and therapy of hearing problems and dementia.

Effects of light smoking on extra-high-frequency auditory thresholds in young adults

There have been few reports showing a correlation between hearing levels and life style in young people. In this study, we succeeded in sensitively evaluating hearing levels in 51 young male adults of 21-23 years in age by 12 k Hz extra-high-frequency auditory thresholds, which cannot be measured by usual audiometry devices for clinical use. Noise exposure, alcohol consumption and sleeping time did not affect hearing levels in young adults. Auditory thresholds of 12 kHz frequency in smokers were significantly (p < 0.05) higher than those in non-smokers, while there were no differences in 1 kHz, 4 kHz and 8 kHz frequencies of hearing levels between smokers and non-smokers. Since the Brinkman Index (BI; cigarettes/day multiplied by number of years) of smokers in this study was from 12 to 60, our results suggest that even light smoking of less than 20 cigarettes/day for 3 years can result in the development of hearing loss of 12 kHz frequency in young adults. Binary logistic regression analysis again showed a correlation between hearing loss (≥ 40 dB of auditory thresholds in 12 kHz frequency) and light smoking (12 ≤ BI ≤ 60). Thus, this study showed that auditory threshold at 12 kHz frequency could be a sensitive marker for hearing in young adults. More importantly, we for the first time provided epidemiological evidence that light smoking might affect hearing level at 12 kHz frequency and revealed a new risk of light smoking.