EE 2008

This lecture gives the brief explanation to questions like:

Readability dependence on sound pressure level in room

The Effects of Noise The noise level has an important bearing on human well-being, even in those cases where it is not perceived consciously. The most common effects are listed in order of increasing gravity: Distraction The concentration on the work at hand may be more or less hampered by the environmental noise. Beware also of surprise reactions to sudden noises when executing critical operations. Conversely, extremely low levels of noise, for instance in acoustic laboratories or recording studios, may also be experienced as irritating and thereby have an adverse effect on attention. Masking effects Hearing may be temporarily impaired by a sudden, intense sound. Continuous noise will, by masking certain frequencies, make understanding of speech more difficult. Auditive fatigue makes itself felt particularly in frequency band of 3 to 6 kHz and may, if persistent, lead to permanent hearing impairments. Auditive trauma, lesions to the auditive system accompanied by violent pain, can result from exposure to very intense noise. Professional deafness, irreversible hearing insufficiency, may result from prolonged exposure to noise levels exceeding 90 dB(A). Such effects may not appear immediately but sometimes with a considerable delay. Deafness can have very serious consequences for the health, the professional and private life and, in general, for the physical and psychological equilibrium of the individual. Since hearing problems represent a considerable portion of professional illnesses, noise must get very serious considerations when the quality of the work situation is evaluated.

Protective Measures Legal protective measures ("Protection against Noise") are required if: the noise level exceeds 85 dB(A): hearing protection devices must be worn and a program must be instituted to reduce the level to below 85 dB(A) by means of collective protective devices. the noise level exceeds 105 dB(A): unauthorised entry is prohibited. By way of exception, work lasting a very short time may be done by persons wearing suitable individual protections. Other protective measure include: information about the danger for a better understanding of the effects of noise, warning signs indicating zones with high levels of noise, personal protective reactions, such as reducing the noise by closing a door, getting away from the noisy region, limiting the exposure time to the strict minimum, reducing the noise level by technical means, such as isolation, absorption or modification of the source, respecting the recommendations for maximal admissible sound levels.

Impact of noise on sleeping Tendency to sustain in noisy environment Sick people and noise Childern and noise Loud music Other factors impact