Noise and Hearing Loss Prevention

Publications and Products

NIOSH Presentations

Application of Health Communication Theories
PDF Version (1.4 MB)
NIOSH presentation addressing occupational hearing loss and prevention. Presented on August 9, 2000, in Baltimore, MD, at the Third Annual Force Health Protection Conference.

Noise-Induced Hearing Loss in the Construction Industry
PDF Version (1.79 MB)
NIOSH presentation addressing occupational hearing loss and prevention in the construction industry. Presented on March 15, 2001, in Washington, DC, at OSHA's Advisory Committee for Construction Safety and Health (ACCSH).

New Design Concept for an Impulse Noise Dosimeter
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Presented at the NIOSH/NHCA Best Practices Workshop in Cincinnati, OH in May 2003. It discusses a new design concept for an impulse noise dosimeter. The presentation discusses the limitations in existing noise dosimeters and proposes new concept design for a dosimeter that's capable of measuring impulse noise correctly and characterizing the exposure based on impulse noise arameters that have been linked to hearing damage from impulse noise.

Limitations of Integrating Impulse Noise When Using Dosimeters
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Presented at the AICHE conference in San Diego in 2002, this presentation describes limitations of using contemporary dosimeters in impulsive noise environments.

Personal Noise Exposure Assessment from Small Firearms
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Presented at the Acoustical Society of America conference in Nashville, TN in February 2003, this presentation discusses personal noise assessment from small firearms and how the current damage risk criteria can be applied to document safe exposure.

Preventing Hearing Loss from Chemical and Noise Exposures
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The objective of this project is to develop guidelines on how to address the auditory risk from chemical exposure or mixed noise and chemical exposures. There are chemicals commonly found in industry, construction, and agriculture that are hazardous to hearing alone, or when combined with noise. There is very little awareness in the occupational health community of the chemical hazards to hearing. Standard hearing conservation practices focus entirely on noise and do not take into account the potential risk to hearing posed by chemical exposures. When chemical exposure limits are set, rarely are auditory effects are taken into consideration. NIOSH has been a pioneer in the research on the effects of chemicals and noise on hearing and now is in a position to develop recommendations for the occupational health community, and disseminate this information to its stakeholders. Ultimately, information obtained in this effort could be used to reduce the risk of work-related hearing loss and increase awareness of the ototoxic potential of chemicals alone and when combined with noise.

Issues of Hearing Protection Devices Used in Manufacturing and Mining
PDF Version (453 KB)
Presented at the 144th Meeting of the Acoustical Society of America in Cancun, Mexico, this presentation examines the reasons offered by workers for not consistently using hearing protectors. Study groups were comprised of workers from manufacturing or mining, in the US, Brazil and Sweden. With the groups in Brazil and Sweden, data on work history, psychosocial aspects of their job, medical history, present health, stress, occupational and non-occupational exposures to noise or chemicals and lifestyle factors were collected through an interview. The workers in the US participated of focus group discussions which attempted to describe hearing protection issues from the workers' perspective, mainly the problems which workers report in the use of hearing protection devices. The information gathered from all groups was consistent. The variables significantly associated with the decision for not consistently wearing hearing protectors included interference with communication, interference with job performance, comfort issues, and self-perception of hearing condition.

Performance of Electroacoustic Hearing Protectors
Flash Version (748KB)
The spectral and temporal response characteristics of five models of electroacoustic earmuffs (Bilsom 707 Impact II, Peltor Tactical 6s, Howard Leight Lightning and Thunder w/ProEars, and Silencio Electronic Low Pro hearing protectors) were measured with noise created by small arms fire from a 0.223 caliber rifle and a 9mm handgun. Each hearing protector was tested in the fully-amplified (active) and no amplification (passive) conditions. The protectors were measured on an acoustic test fixture designed for high-level noise measurements. The protected and unprotected signals were recorded to digital audio tape and analyzed off-line. The reduction of peak sound pressure levels ranged between 16 and 32 dB for both the active and passive conditions. The time-averaged acoustic waveforms underneath the protectors exhibited little difference between active and passive conditions. The active electroacoustic performance approaches the passive attenuation performance. Auditory damage units were calculated for the unprotected and protected responses using the AHAAH cochlear model [Price and Kalb, J. Acoust. Soc. Am. 90, 219-227 (1991)].

Do sound restoration hearing protectors provide adequate attenuation for gunfire noise?
Flash Version (1.1 MB)
Sound restoration earmuffs, also known as active nonlinear earmuffs, have an electronics package installed in a passive earmuff shell or earplug body.  The electronics package consists of a microphone placed on the outside of the ear cup or earplug and a limiting amplifier driving a loudspeaker placed inside the ear cup or the earplug.  The devices are designed to provide unity gain or better gain to low-level signals and to shut off when sound exceeds a given level. The effects of several sound restoration active nonlinear earmuffs and one active two nonlinear orifice earplugs on gunfire for several different weapon types were analyzed.  In general, the nature of the electronics packages was such that the studied devices provided the same attenuation when turned on as when turned off.  However, as with passive devices, a single protector, be it by earplug or earmuff, appears to be inadequate for gunfire when more than just a few shots are fired. Sound restoration Active level-dependent earmuffs are best used with a well-fitted earplug, since the electronics can compensate for both the insertion loss of the earmuff and the earplug.. It is not clear how active-level dependent earplugs would work with passive or active-level dependent earmuffs. However, nonlinear orifice earplugs may not provide sufficient protection for extended sessions of target practice.