Hearing Conservation

The program describes the safe work practices and procedures to manage occupational noise exposure for CSUN employees.

I.  Purpose/Scope

The purpose of the Hearing Conservation Program is to establish a coordinated approach toward controlling excess occupational noise exposure on campus and to reduce/prevent exposure when/where needed.   The requirements of this document apply to all employees exposed to an 8-hour time weighted average (TWA) noise level of 85 dBA or greater as measured on the A scale. 

II.  Definitions

  • Action Level:  Any 8-hour time-weighted average of 85 decibels measured on the A- scale, slow response, or equivalently, a dose of fifty percent.
  • Audiometric Testing: A method used for determining an individual’s hearing threshold level and measuring if an individual has experienced hearing loss over time.  Audiometric tests are performed by audiologists or technicians who are certified by the Council of Accreditation in Occupation Hearing Conservation.  
  • Audiogram: A chart, graph, or table resulting from an audiometric test showing an individual’s hearing threshold levels as a function of frequency.
  • Baseline Audiogram: The audiogram against which future audiograms are compared.
  • Criterion Sound Level:  A sound level of 90 dB.
  • Decibel (dB):  Unit of measurement of sound level.
  • (dBA) Decibel-a-Weighted:  A unit of measurement of sound level corrected to the A-weighted scale, as defined in ANSI S 1.4-1971 (R1976), using a reference level of 20 micropascals.
  • Hertz: Unit of measurement of frequency, numerically equal to cycles per second.
  • Sound Level:  Ten times the common logarithm of the ratio of the square of the measured A-weighted sound pressure to the square of the standard reference pressure of 20 micropascals.  Unit: decibels (dB). For use with this regulation, SLOW time response, in accordance with ANSI S1.4-1971 (R1976), is required.
  • Sound Level Meter:  An instrument for the measurement of sound levels.
  • Standard Threshold Shift: OSHA's definition of a standard threshold shift is a change, relative to baseline, of 10 dB or more in the average hearing level at 2000, 3000, and 4000 Hz in either ear. 

III.  Exemptions/Exclusions


IV.  Responsibilities

  • Departments / Human Resources:
    • New employees assigned to jobs that are at or exceed the Action level shall be given a baseline audiogram within the first two weeks of employment.
  • Environmental Health & Safety (EH&S):
    • Establish and update the written Hearing Conservation Program.
    • Provide consultation/training to departments who fall within the Program.
    • Conduct noise surveys in response to department requests or as general noise survey.
    • Assist departments in developing methods for noise abatement, reduction or control.
    • Recommend personal protection devices for applicable tasks/departments.
    • Make exposure measurements, training and audiometric test records available.
    • Determine which types of areas are defined as excess occupational noise areas on campus.
  • Supervisors:
    • Ensure that noise control is considered when procuring equipment, machinery, and tools.
    • Identify work areas/tasks that may expose employees to harmful levels of noise and notify the EH&S Office.
    • Develop methods for noise abatement, reduction or control.
    • Ensure employees covered by the Hearing Conservation Program attend annual Hearing Conservation training as well as audiograms and comply with all appropriate procedures.
    • Ensure that employees are not exposed to excess occupational noise at least 14 hours prior to their audiogram.
    • Provide appropriate personal protective equipment to affected employees; enforce the use of such devices when required; ensure that devices are kept in good condition and maintained in a sanitary manner.
    • Maintain all reporting employees’ hearing conservation documentation.
  • Employees:
    • Exposed employees are ultimately responsible for wearing hearing protection devices whenever they are working in noisy environments.
    • Read and comply with all appropriate hearing conservation safety procedures while performing assigned duties.
    • Identify areas which have high levels of occupational noise and notify their supervisors. 

V.  Controlling/Reducing Occupational Noise Exposure

  • Engineering Controls:
    • Noise control through engineering practices is the preferred control method as it is an attempt to remove the hazard.  This allows the sound intensity to be reduced either at the source or in the hearing zone of the worker.  Examples include:
    • Replacing worn, loose, or unbalanced parts (e.g. replace mufflers when needed on gasoline engines);
    • Lubricating machines;
    • Substituting the machinery or process;
    • Modifying the path between the noise source and the worker.  This may include installing absorption materials, silencers, barriers and acoustical enclosures around the noise sources.
  • Administrative Controls:
    • Administrative controls limit the length of time workers are exposed to noise in the work area.  Examples include:
    • Rotate workers to job assignments with lower sound exposure levels throughout their 8-hour work day.
    • Schedule machine operating times during off hours to expose fewer workers (when possible).
    • Rotate exposed workers’ shift to reduce exposure time.
  • Personal Protective Equipment:
    • When engineering and/or administrative controls are not feasible hearing protective devices must be used.
    • When either earmuffs or ear plugs are used, the department should have a sufficient variety to ensure that workers can get a good fit.
    • Protective devices should be both effective and comfortable.
    • All workers must be trained before being issued hearing protection. 
    • Workers must wear hearing protectors when:
      • They are exposed to a sound level of 85dBA-TWA or greater and have had a significant threshold shift in hearing.
      • They are exposed to noise in excess of the limits set in Cal-OSHA Title 8, Section 5096 (Appendix A).  

VI.  Audiometric Testing Program

  • The results of the tests are called audiograms.
  • All employees included in the Hearing Conservation Program shall have an audiogram within 6 months of their first exposure.
  • Annual audiograms must be routinely compared to baseline audiograms to determine if a standard threshold shift exists.
  • Employees with standard threshold shifts must be fitted or refitted with adequate hearing protection devices. 

VII.  Training

  • Level of Training:
    • All employees exposed at or above the Action Level must participate in the Hearing Conservation Program.  Participants shall receive annual training in the requirement of this program. 
    • Training shall include the following elements:
      • The effects of high noise levels on hearing.
      • The purpose, advantages, disadvantages, and attenuation characteristics of various types of hearing protection.
      • Instruction on the selection, fitting, use and care of hearing protectors.
      • The purpose of audiometric testing and procedures.
  • Records Retention:
    • Noise exposure documentation shall be maintained by the employees department for a minimum of 2 years.
    • Training records shall be maintained by the employee’s department for a minimum of 3 years.
    • Audiometric tests shall be maintained by the employee’s department for the duration of employee’s employment.
  • Access to Records:
    • All records are to be made available to EH&S upon request.
    • All records shall be provided, upon written request, to employees, former employees and representatives of employees.  

VIII.  Forms Used


IX.  References/Resources


X.  Revision Record






November 2001


Reviewed – updated

November  2008


Update format, definitions and references

May 2009


Update format and review

May 2014


II. Definitions and V. Controlling/Reducing Occupational Noise Exposure format update

June 2018


Update format and links

October 2022