effect of noise on human performance: a clinical trial

Noise is defined as unwanted or meaningless sound that apart from auditory adverse health effects may distract attention from cues that are important for task performance. Human performance is influenced by many job-related factors and workplace conditions including noise level. To study the effect of noise on human performance. The participants included 40 healthy male university students. The experimental design consisted of 3 [sound pressure level] x 3 [noise schedule] x 2 [noise type] factors. To investigate occupational skill performance, some specific test batteries were used: 1] steadiness test, 2] Minnesota manual dexterity test, 3] hand tool dexterity test, and 4] two-arm coordination test. Time duration of test completion was measured as speed response; to determine error response, the time taken during committing an error by participants while performing a task was measured. Speed response obtained from the 4 tests in combined conditions of noise schedule, harmonic index, and sound pressure level was highest for [intermittent, treble, 95 dB], [continuous, treble, 95 dB], [continuous, treble, 85 dB] and [intermittent, treble, 95 dB], respectively. Treble noise was found significant in reducing human performance; also, intermittent noise, especially at high pressure levels, was responsible for worsening environmental conditions during performing a task

[Occupational noise exposure evaluation in drivers of bus transportation of Tehran City]

Noise in large cities is considered by the World Health Organization to be the third most hazardous type of pollution. Buses are an interesting object of study in the theme of noise pollution. They are at the same time a source of urban environmental [traffic] noise and occupational noise exposure source for drivers. The object of this study is Occupational noise exposure evaluation in drivers of bus transportation of Tehran city. Noise levels in 90 buses were sampled in three separate sub-sample including [1]30 Ikaroos buses [2]30 Man buses [3]30 Shahab buses, which were selected by simple random sampling. Noise exposure level was normalized to a nominal 8-h working day [LEX, 8h]. Simultaneous Octave Frequency Analysis were measured and sound intensity level [SIL] for bus drivers were calculated. Results, which are obtained from separate buses were compared together and too with standard levels. the normalized noise exposure levels [LEX, 8h] in Ikaroos bus drivers[82dB A] were higher than that of in Man bus drivers [77/6dB A] and this Values were higher than that of in Shahab bus drivers[75dB A].SIL values for Ikaroos bus drivers were higher than other that of other bus drivers. Results obtained of Frequency Analysis showed that age of buses in mid frequencies ws a meaningful on noise increase. Results showed that type and age of buses were effective factors in drivers' noise exposure levels [LEX, 8h], which was consistent with previous studies in this field