159 Hearing Protection: Basic

Glossary

A

• Action level. An 8-hour time-weighted average of 85 decibels measured on the A-scale, slow response, or equivalently, a dose of fifty percent.
• Acoustic trauma. Injury to the hearing mechanisms in the inner ear due to a sudden burst of loud noise, such as an explosion.
• Acoustic Dosimeter. A device used to measure the cumulative exposure to sound over a specified period, typically in noisy work environments, by calculating the total noise dose.
• Administrative control. A method of controlling workplace hazards by changing workers' activities to reduce their exposure to a hazard.
• Administrative controls (NIOSH). Procedures implemented by management to reduce noise exposure by altering work schedules or tasks, as recommended by NIOSH.
• Amplify. Increase the volume of (sound).
• Attenuation. The reduction of the force, effect, or value of sound, especially in the context of hearing protection devices that reduce noise exposure levels.
• Audiogram. A graph that shows the softest sounds that a person can hear at different frequencies.
• Audiometric zero. The lowest sound pressure level that the average young adult with normal hearing can hear.
• Audiometry. The testing of a person's ability to hear various sound frequencies. The test is performed with the use of electronic equipment called an audiometer.
• Auditory. Of or relating to the sense of hearing.
• Asphyxiant. A substance that can cause unconsciousness or death by suffocation (asphyxiation).

B

• Baseline audiogram. The reference audiogram against which future audiograms are compared.
• Binaural. Of, relating to, or used with both ears.

C

• Canal caps. A type of hearing protection device that covers the entrance of the ear canal to block noise, often held in place by a headband.
• Centers for Disease Control and Prevention (CDC). A U.S. federal agency under the Department of Health and Human Services that provides health and safety guidelines, including on hearing conservation in the workplace.
• Circumaural protectors. Ear muffs or similar devices that completely enclose the ear to provide hearing protection.
• Continuity. The unbroken and consistent existence or operation of something over a period of time.
• Criterion sound level. A sound level of 90 decibels.

D

• Decibel (dB). A unit of sound-pressure level, abbreviated dB. Decibels indicate the pressure of sound. Sound waves transfer that pressure from place to place and are measured in units on a logarithmic scale.
• Decibel A-weighted filter (dBA). A decibel rating commonly used for measuring sound levels. Used for lower levels, it corresponds to people's natural hearing recognition and is less sensitive to very low and very high frequencies.
• Dosimeter. A device worn by a worker for determining accumulated noise exposure.
• Dosimetry. Often refers to the status of wearing a personnel badge that measures and monitors dose. It may also refer to dose history and the records where dose history is maintained.

E

• Eardrum. A membrane in the ear canal between the external ear and the middle ear.
• Earplugs. A hearing protection device inserted into the ear canal to block harmful noise. They are typically made of foam, silicone, or other soft materials.
• Ear muffs. A type of hearing protection worn over the ears, typically consisting of sound-attenuating cups connected by a headband.
• Eight-hour time-weighted average. An average exposure weighted to account for time and changing noise levels over eight hours.
• Engineering controls (NIOSH). Physical modifications to equipment or the workplace that reduce noise levels, such as adding sound barriers or using quieter machinery, as recommended by NIOSH.
• Exposure limit. The maximum amount of sound a worker can be exposed to without requiring hearing protection, often regulated by occupational safety guidelines.

F

• Frequency. The number of times per second that the sine wave of sound repeats itself, or that the sine wave of a vibrating object repeats itself. Now expressed in hertz (Hz), formerly in cycles per second (cps).

G

H

• Hair cells. Sensory cells in the inner ear that transform the mechanical energy of sound into nerve impulses.
• Hearing Conservation Amendment (OSHA). OSHA regulation that mandates hearing conservation programs in workplaces where workers are exposed to 85 decibels or more over an 8-hour period.
• Hearing conservation program. A program designed to protect workers' hearing by monitoring noise exposure, providing hearing protection, and conducting regular audiometric testing.
• Hearing Conservation Program (OSHA). An OSHA-mandated program aimed at preventing noise-induced hearing loss in workers, which includes noise monitoring, audiometric testing, training, and hearing protection devices.
• Hearing protection device (HPD). Equipment used to reduce noise exposure to safe levels, including earplugs and earmuffs.
• Hearing Protectors (NIOSH). Devices such as earplugs or earmuffs used to reduce noise exposure, recommended by NIOSH to prevent noise-induced hearing loss.
• Hearing threshold. The sound level below which a person's ear is unable to detect any sound. For adults, 0 dB is the reference level. A threshold shift is an increase in the hearing threshold for a particular sound frequency.
• Hertz. Unit of measurement of frequency, numerically equal to cycles per second, abbreviated Hz.
• Hierarchy of Controls (NIOSH). A framework for controlling workplace hazards, starting with elimination, substitution, engineering controls, administrative controls, and personal protective equipment (PPE), including hearing protection.

I

• Industrial Hygiene. The science of anticipating, recognizing, evaluating, and controlling workplace conditions that may cause workers' injury or illness. Industrial hygienists use environmental monitoring and analytical methods to detect the extent of worker exposure and employ engineering, work practice controls, and other methods to control potential health hazards.
• Inner ear. The inner portion of the ear involved in hearing and balance.
• Integrating Sound Level Meter. A type of dosimeter that measures sound pressure levels and integrates them over time to assess average noise exposure, often used in occupational settings.
• Interdisciplinary. Of or relating to more than one branch of knowledge.

J

K

L

• Logarithmic scale. A scale that expresses values over a very large range. Each interval on a logarithmic scale is some common factor larger than the previous interval. A typical factor is 10; the values on such a scale read: 1, 10, 100, 1,000, 10,000, and so on.

M

• Middle ear. The middle portion of the ear consisting of the eardrum and an air-filled chamber lined with mucous membrane.
• Monaural. Of or involving one ear.

N

• Neurotoxicity. The capability of inducing adverse effects in the central nervous system, peripheral nerves or sensory organs. A chemical is considered to be neurotoxic if it is capable of inducing a consistent pattern of neural dysfunction or change in the chemistry or structure of the nervous system.
• NIOSH Recommended Exposure Limit (REL). The maximum noise level of 85 decibels over an 8-hour period that NIOSH recommends to protect workers from hearing loss.
• Noise. Sound that is noticeably unpleasant or undesired or that interferes with one's hearing.
• Noise-induced hearing loss. The result of exposure to sound of sufficient intensity and duration to cause a decrease in hearing ability.
• Noise dosimeter. An instrument that integrates a function of sound pressure over a period of time in such a manner that it directly indicates a noise dose.
• Noise Exposure Limits (OSHA). Regulatory noise exposure limits set by OSHA, where employers are required to take action when noise levels exceed 85 decibels averaged over an 8-hour period.
• Noise Reduction Rating (NRR). A measure used to determine the effectiveness of a hearing protection device in reducing noise exposure, expressed in decibels.

O

• Occupational Noise Exposure Standard (OSHA). OSHA regulation (29 CFR 1910.95) that defines the permissible noise exposure limits for workers and outlines requirements for hearing conservation programs.
• Octave. The interval of eight diatonic degrees between two tones of the same name, the higher of which has twice as many vibrations per second as the lower.
• Optical card. A card with information recorded on an optical memory stripe, similar to compact discs.
• Outer ear. The external portion of the ear, including the canal leading to the eardrum.
• Otolaryngologist. A physician specializing in diagnosis and treatment of disorders of the ear, nose and throat.
• Ototoxic. Damage to the ear (oto-), specifically the cochlea or auditory nerve and sometimes the vestibular system, by a toxin.

P

• Passive hearing protection. Hearing protection devices that rely solely on their physical structure to block or reduce noise without using electronics.
• Pathology. The study of disease. Pathology has been defined as "that branch of medicine which treats of the essential nature of disease."
• Peak Dosimeter. A dosimeter designed to measure and record peak sound pressure levels, typically used to detect sudden, loud noises like explosions or machinery crashes.
• Permanent hearing loss. Irreversible damage to hearing ability, often caused by prolonged exposure to excessive noise.
• Permissible Exposure Limit (PEL). The maximum legal noise exposure level established by OSHA, set at 90 decibels over an 8-hour time-weighted average.
• Personal monitoring. A method of measuring sound levels near individual workers, usually over eight hours.
• Personal Noise Dosimeter. A small, wearable dosimeter that continuously records sound exposure over a period, allowing for real-time monitoring and analysis of a worker's noise exposure.
• Personal protective equipment (PPE). Equipment worn to minimize exposure to hazards, including hearing protection devices such as earplugs and earmuffs.
• Personal Protective Equipment (PPE) Standards (OSHA). OSHA's regulations and guidelines that outline the use of hearing protection devices as part of personal protective equipment to prevent hearing loss in noisy environments.
• Permanent threshold shift. A permanent decrease in hearing ability at a specified frequency as compared with a previously established reference level.
• Pitch. The property of a sound determined by the frequency of the waves that produce it; the highness or lowness of sound.
• Protective communication devices. Hearing protection devices that allow communication while still offering protection from loud noises, often using electronic noise-canceling technology.

Q

R

• Recommended Exposure Limit (REL) (NIOSH). The noise exposure limit recommended by NIOSH, set at 85 decibels over an 8-hour time-weighted average to prevent noise-induced hearing loss.

S

• Safety climate. The general level of safety awareness and commitment among management and workers in the organization.
• Solvent. A substance, usually a liquid, capable of dissolving another substance.
• Sound. The subjective sensation of hearing something - usually transmitted in a material medium, typically air. Sound is measured in decibels.
• Sound Dosimeter. A personal monitoring device used to measure a worker's cumulative exposure to sound levels over time, typically in noisy environments. It calculates the total noise dose by integrating sound pressure levels over a specified period, such as an 8-hour workday, to ensure compliance with occupational noise exposure limits.
• Sound survey. Describes a variety of methods for measuring sound levels, including basic survey, detailed survey, and engineering survey; includes monitoring exposure levels over extended time periods, such as an eight-hour work day.
• Standard Threshold Shift - OSHA. A change in hearing threshold, relative to the baseline audiogram for that employee, of an average of 10 decibels (dB) or more at 2000, 3000, and 4000 hertz (Hz) in one or both ears.

T

• Temporary threshold shift. A temporary impairment of hearing ability.
• Time-weighted average (TWA) sound level. That sound level, which if constant over an 8-hour exposure, would result in the same noise dose as is measured.
• Tinnitus. Ringing in the ear or noise sensed in the head. Onset may be due to excessive sound and persist in the absence of acoustical stimulation (in which case, it may indicate a lesion of the auditory system).
• Toxicity. The degree to which a substance (a toxin or poison) can harm humans or animals.
• Threshold limit value (TLV). The level of noise exposure that most workers can experience without an increased risk of hearing damage, typically defined by occupational safety organizations.
• Threshold Limit Value (TLV) (NIOSH). A guideline for noise exposure levels developed by NIOSH to help employers protect workers' hearing by limiting their exposure to hazardous noise levels.

U

V

• Ventilated earplugs. A type of earplug designed with small holes to allow some air and sound to pass through, offering protection while allowing for some auditory awareness.
• Vestibular. Of or relating to a vestibule, particularly that of the inner ear, or more generally to the sense of balance.
• Vibration Dosimeter. A dosimeter that measures exposure to vibration, often used in conjunction with noise dosimetry in environments where both noise and vibration are present, such as construction or manufacturing.

W

• Work-practice control. A type of administrative control; emphasizes safe work practices and procedures.