What can be done to reduce the hazard from noise? Noise controls are the first line of defense against excessive noise exposure. The use of these controls should aim to reduce the hazardous exposure to the point where the risk to hearing is eliminated or minimized. With the reduction of even a few decibels, the hazard to hearing is reduced, communication is improved, and noise-related annoyance is reduced. There are several ways to control and reduce worker exposure to noise in a workplace. Engineering controls that reduce sound exposure levels are available and technologically feasible for most noise sources. Engineering controls involve modifying or replacing equipment, or making related physical changes at the noise source or along the transmission path to reduce the noise level at the worker's ear. In some instances the application of a relatively simple engineering noise control solution reduces the noise hazard to the extent that further requirements of the OSHA Noise standard (e.g., audiometric testing (hearing tests), hearing conservation program, provision of hearing protectors, etc…) are not necessary. Examples of inexpensive, effective engineering controls include some of the following: (a) Choose low-noise tools and machinery (e.g., Buy Quiet Roadmap (NASA). (b) Maintain and lubricate machinery and equipment (e.g., oil bearings). (c) Place a barrier between the noise source and employee (e.g., sound walls or curtains). (d) Enclose or isolate the noise source. Examples of Engineering Controls: Administrative controls are changes in the workplace that reduce or eliminate the worker exposure to noise. Examples include: (a) Operating noisy machines during shifts when fewer people are exposed. (b) Limiting the amount of time a person spends at a noise source. (c) Providing quiet areas where workers can gain relief from hazardous noise sources (e.g., construct a sound proof room where workers' hearing can recover - depending upon their individual noise level and duration of exposure, and time spent in the quiet area). (d) Restricting worker presence to a suitable distance away from noisy equipment. (e) Controlling noise exposure through distance is often an effective, yet simple and inexpensive administrative control. This control may be applicable when workers are present but are not actually working with a noise source or equipment. Increasing the distance between the noise source and the worker, reduces their exposure. In open space, for every doubling of the distance between the source of noise and the worker, the noise is decreased by 6 dBA. Hearing protection devices (HPDs), such as earmuffs and plugs, are considered an acceptable but less desirable option to control exposures to noise and are generally used during the time necessary to implement engineering or administrative controls, when such controls are not feasible, or when worker's hearing tests indicate significant hearing damage. See more from topic source: https://www.osha.gov/html/a-z-index.html