CAOHC HEARING CERTIFICATION EXAM LATEST VERSION 2025

Unit of measurement for frequency (pitch) - -Hertz (Hz) Unit of measurement for intensity (loudness) - -Decibel (dB) Risk of damage from noise - -How loud (intensity) and how long (duration) Steady-state or continuous noise, e.g. generator - -Lasts 1 second or longer Impulse or Impact noise, e.g. gunfire or nail gun - -Lasts less than one second Parts of the outer ear - -Pinna and external auditory canal Parts of the middle ear - -Tympanic membrane, ossicles, eustachian tube Eustachian tube (auditory tube) - -Tube connecting the middle ear to the pharynx and equalizes middle ear space with atmospheric pressure Conductive HL occurs here - -Outer or middle ear Sensorineural hearing loss - -Hearing loss resulting from damage to the inner ear (cochlea) or the auditory nerve Noise-induced hearing loss (NIHL) - -Condition caused by the destruction of hair cells in the inner ear, the organs responsible for hearing, as a result of sounds that are "too long, too loud, or too close"; a sensorineural hearing loss Mixed hearing loss - -Combination of conductive and sensorineural types in the same ear Middle ear bones (ossicles) - -Malleus (hammer), incus (anvil), stapes (stirrup) Possible early symptoms/signs of noise induced hearing loss - -Tinnitus; difficulty understanding in presence of background noise; read visual cues Auditory effects of noise - -NIHL; tinnitus; hyperacusis Non-auditory effects of noise - - annoyance sleep disturbance attention CAOHC CAOHC CAOHC motivation stress reactions cardiovascular problems endocrine problems 3 foot rule - -Good rule of thumb to recognize hazardous noise exposure levels/situations: the rule is: if you have to shout at arms length (~3ft), in order to be understood over the background noise, then you're likely exposed to hazardous noise levels & should be wearing hearing protection to prevent NIHL OSHA (Occupational Safety and Health Administration) versus National institute of Occupational Safety and Heath (NIOSH) - -OSHA enforces regulation and NIOSH recommends best practice based on science and research Sound pressure level (SPL) versus hearing level (HL) - -SPL describes noise measurements taken with a sound level meter or dosimeter; HL describes threshold levels obtained with an audiometer; 0 dB HL is not equal to 0 dB SPL Noise Dosimeter - -A sound measurement device used to record the amount of sound exposure over an extended period of time (usually a work day) Personal vs. Area Sound level meter - -Uses a microphone to sense pressure variations in sound waves; the meter converts those pressures directly into decibels; provides a noise measurement that is a snapshot in time. Time Weighted Average (TWA) - -An evaluation of exposures that is time-weighted over an established period. It allow the exposure levels to be averaged generally over an eight-hour time period. OSHA exchange rate - -5 dB; for every 5 dB you go over the PEL of 90dBA TWA you half the allowable time of exposure OSHA Action Level for noise - -85dBA TWA Sound Level Meter A-weighted Scale - -OSHA requires this scale as it resembles how the human ear responds to sound (humans hear best from 500 Hz to 4000 Hz) Human Frequency Response at Birth - -20 Hz to 20,000 Hz (20 kHz) Human speech frequency range - -250 Hz to 4000 Hz Elements of a Hearing Conservation Program - -Noise hazard assessment; engineering/administrative controls; annual hearing monitoring; annual training/education; hearing protection; recordkeeping CAOHC CAOHC OSHA Noise Amendment - -29 CFR 1910.95 Hughson-Westlake Procedure - -Common procedure for obtaining threshold; the audiologist decreases stimulus intensity by 10 dB with a (+) response and increases by 5 dB with a (-) response Hearing threshold level - -Lowest intensity level responded to at least 50% of the time Excessive noise levels will impact these test frequencies during a hearing exam - -Low frequencies e.g. 500 Hz First frequency always tested on an occupational hearing exam - -1000 Hz 1000 Hz retest - -Done as a validity check on first ear tested; thresholds should be within 5dB or should reinstruct patient and start test over Presbycusis - -A gradual loss of sensorineural hearing that occurs as the body ages Professional Supervisor In a HCP - -Responsible for oversight of Audiometric testing; reviews problem audiograms; must be an audiologist or physician Elements of a Hearing Conservation Program - -Mandatory and includes: exposure monitoring, audiometric testing, hearing protection, employee training, record keeping, and program evaluation Noise Controls - -At the source (preferred), along the path, at the receiver Industrial Hygienist - -Responsible for assessment of hazards that may affect workers as well as hazards that may impact the community. NRR - -Noise Reduction Rating; number determined in a laboratory Hearing protection derating - -OSHA recommends to reduce NRR in half Hearing protection types - -Noise reduction devices worn over the ear (noise muffs) or inside the ear canal (earplugs) in work or recreational settings with high noise levels Best hearing protection - -The one that is worn (consistently and properly) Dual hearing protection NRR - -After derating add additional 5dB of protection Inverse square law for noise - -For every doubling of distance away from a noise source you reduce the level by 6 dB CAOHC CAOHC Noise doubling rule - -If you add two identical noise sources you add 3dB to the Level (100 dB + 100 dB = 103 dB) Administrative noise controls - -Changes made by employer such as changing work schedules to reduce noise hazard risk to employees OSHA standard threshold shift - -10dB average change at 2000 Hz, 3000 Hz, and 4000 Hz, when compared to a baseline , in one or both ears OSHA Recordable Standard Threshold Shift for Hearing Loss - -3 criteria: 10dB average shift at 2, 3, and 4kHz, compared to baseline, AND 25 dB average HL at 2, 3, and 4 kHz in the same ear on current audiograms, AND determined to be work-related Collapsing ear canal - -Occurs naturally in some individuals during audiometric testing earphones cause auricle to move forward collapsing the canal and causing an artificial hearing loss; Insert earphones should be used Cochlea - -A coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses; damage from hazardous noise occurs here. Microprocessor audiometer - -Automated computer controlled audiometer Tinnitus - -A jingling; a ringing or buzzing in the ear Type of hearing test done by a certified occupational Hearing conservationist (COHC) - -Air Conduction Pure Tone Threshold Test Hearing Threshold Level (HTL) are recorded on this - -Audiogram (can be serial or graphic) Baseline Hearing Test Must Be Done Within - -6 months of starting employment (exception for mobile vans is up to 1 year) Type of Hearing Loss that is treatable (medically or surgically) - -Conductive hearing loss Temporary Threshold Shift (TTS) - -Brief exposure to intense noise that will ordinarily recover with auditory rest Hearing Thresholds Tested are: - -500, 1000, 2000, 3000, 4000, and 6000 Hz; 8000 Hz is optional but recommended. Audiometric zero is: - -0 dB HL; this is not an absence of sound HL scale has been normalized to healthy adult hearing CAOHC CAOHC Vertical axis on a graphic Audiogram shows this: - -Intensity levels which are measured in Decibels (softest at the top, loudest at the bottom) Horizontal axis on a graphic Audiogram shows this: - -Frequencies which are measured in Hertz (low to high going from left to right) Hearing Baselines are reestablished when you have an STS because: - -You don't want to identify the same shift each year Days to notify individual of an STS in writing - -21 days OSHA versus NIOSH Noise Permissible Exposure Limit (PEL) - -90 dBA PEL for OSHA; 85 dBA PEL recommended by NIOSH OSHA recommendations for Audiometric Records - -Maintain for duration of employment; NIOSH recommends duration of employment + 30 years Sound Level Meter Microphone Type Required by OSHA - -Minimum of Type 2 microphone Formable Earplugs are: - -Disposable when no longer return to shape and soiled Pre-formed earplugs: - -Can be washed with mild soap and water and reusable Noise muff cushions - -Should completely cover ear and seal against the face; cushions should be replaced when damaged and no longer seal effectively. Hearing Aids and Hearing Test - -Tests are to be done without hearing aids Function of the Outer Ear - -Collecting sound and sending it to the eard