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2007| April-June | Volume 9 | Issue 35
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Hearing, communication and cognition in low-frequency noise from armoured vehicles
Ann Nakashima, Sharon M Abel, Matthew Duncan, David Smith
April-June 2007, 9(35):35-41
An experiment was performed to study auditory perception and cognitive function in the presence of low-frequency dominant armoured vehicle noise (LAV III). Thirty-six normal hearing subjects were assigned to one of three noise backgrounds: Quiet, pink noise and vehicle noise. The pink and vehicle noise were presented at 80 dBA. Each subject performed an auditory detection test, modified rhyme test (MRT) and cognitive test battery for three different ear conditions: Unoccluded and fitted with an active noise reduction (ANR) headset in passive and ANR modes. Auditory detection was measured at six 1/3 octave band frequencies from 0.25 to 8 kHz. The cognitive test battery consisted of two subjective questionnaires and five performance tasks. The earmuff, both in the conventional and ANR modes, did not significantly affect detection thresholds at any frequency in the pink and vehicle noise backgrounds. For the MRT, there were no significant differences between the speech levels required for 60% correct responses for three ear conditions in the pink and vehicle noise backgrounds. A small but significant (4 dB) increase in speech level was required in pink noise as compared to vehicle noise. For the serial reaction time task, the mean response time in the vehicle noise background (751 ms) was significantly higher than in pink noise and quiet (709 and 651 ms, respectively). The mean response time in the pink noise background was also significantly higher than in quiet. Thus, the presence of noise, especially low-frequency noise, had a negative effect on reaction time.
What do patterns of noise in a teaching hospital and nursing home suggest?
T Bharathan, D Glodan, A Ramesh, B Vardhini, E Baccash, P Kiselev, G Goldenberg
April-June 2007, 9(35):31-34
: Noise pollution is known to cause deleterious effects on human health and may especially affect frail elderly patients with poor mental and physiologic reserve.
Aims of the study
: (i) to learn levels and time- and place-patterns of noise in an urban community teaching hospital (TH) and affiliated urban nursing home (NH); (ii) to compare levels and patterns of noise in both institutions.
Recordings were obtained in three areas of the TH: emergency room (ER), intensive care units (ICU), and medical-surgical floors (HF) - nurses' stations and patients' rooms. On nursing home floors (NHF), noise levels were recorded at nurses' stations and in patients' rooms. In all areas of the hospital and NH, noise levels were in range of 55-70 dB and exceeded the 40-50 dB limit recommended by the EPA. In ER and ICU, noise level was higher on weekdays than weekends. In ICU and on HF, noise level was higher during mid-day hours during mornings and evenings. The highest noise level was recorded in ER followed by ICU and HF. On HF, nurses' stations were noisier than patients' rooms. Noise level was higher in the TH than in the NH. On NHF, noise level was similar on weekdays and weekends. Noise was stronger at nurses' stations than in patients' rooms and stronger in the mornings and evenings than during mid-day hours. Patterns of noise followed the human factor activities observed in both facilities.
: The level of noise in both facilities was above the recommended limit and presents an environmental stressor for a frail elderly patient. With transfer from NH to TH exposure to this stressor is increased. Time- and place-patterns of noise in both institutions suggest that human factor is a major source of noise pollution. This pollution is, therefore, potentially modifiable.
Clamping pressure and circum-aural earmuffs
April-June 2007, 9(35):45-50
Some individuals must wear hearing protectors in order to reduce their noise exposure even after all other avenues of exposure control have been exhausted. However, is it reasonable to expect these individuals to wear earmuffs for long, continuous periods? Measurements of 39 commonly available earmuffs show that in all cases, the pressures experienced on the side of the head are sufficient to restrict blood flow and hence over time produce discomfort. For better results and compliance with earmuff use, breakout times may be necessary to alleviate feelings of discomfort.
The socio-economic impact of noise: A method for assessing noise annoyance
April-June 2007, 9(35):42-44
Norwegian authorities have developed and adopted a method for assessing the magnitude of noise impact on a community in quantitative terms. The method takes into account all levels of noise annoyance experienced by all the residents in an area and transforms these data into a single quantity that can also be expressed in monetary terms. This method is contrary to other commonly used assessment methods where only a certain fraction of the impacted people, e.g. those "highly annoyed," is considered.
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