NOISE AND VIBRATION ANALYSIS

OSHA issued its final hearing conservation rules on March 8, 1983. The addition of a hearing conservation program to the noise standard is an outgrowth of a revision first published in 1974. This final ruling has adopted a more performance-oriented approach and therefore is expected to save industry $81.4 million per year over the program proposed in early 1981.

Calling for exposure monitoring, audiometric testing, worker training, recordkeeping and the use, where necessary, of hearing protectors, the hearing conservation program covers all employees exposed to an eight-hour-time-weighted average sound level of 85 decibels (dB), except those employed in construction, agriculture, and oil and gas well drilling and servicing operations.

Employers must make hearing protectors available to workers exposed to noise above a TWA of 85 dB, but use of the protectors is optional unless the worker experiences a permanent, significant shift in his or her hearing level. Hearing protectors must be worn by all employees exposed to a TWA of 90 dB or more.

(Editor's note: On April 19, 1985, OSHA announced that it had resumed frill enforcement of a hearing conservation amendment protecting workers against noise-related hearing loss. The decision followed a November 8, 1984 U.S. Court of Appeals order which struck down the amendment on the grounds that the rule exceeded the authority of OSHA under the OSHAct because a distinction had not been made between occupational and non-occupational hearing loss, which may cause employers to be held responsible for hearing loss incurred off the job. The amendment covers workers (except in agriculture and construction) who are exposed to noise levels at or above 85 decibels over an eight-hour time frame.)

The final rule became effective April 7, 1983, and the required baseline audiometric tests must be completed by March 1, 1984. OSHA believes the primary benefit of the program to be a substantial reduction in the incidence of occupational hearing impairment in the population exposed to workplace noise. Additional benefits anticipated include workplace safety, reduced absenteeism, reduced medical costs, reduced workman's compensation payments and possibly a reduction in cardiovascular illness.

Requirements from the General Industry Standards

(a) Provide protection against the effects of noise exposure when sound levels exceed those in Table G-16 when measured on the A scale of a standard sound level meter at slow response.

When noise levels are determined by octave band analysis, the equivalent A-weighted sound level may be determined from Figure G-9.

BAND CENTER FREQUENCY IN CYCLES PER SECOND

Equivalentt sound level contours. Octave band sound pressure levels may be converted to the equivalent A-weighted sound level by plotting them on this graph and noting the A-weighted sound level corresponding to the point of highest penetration into the sound level contours. This equivalent A-weighted sound level, which may differ from the actual A-weighted sound level of the noise, is used to determine exposure limits from Table G-16.

 

(b.1) When employees are subjected to sound levels exceeding those in Table G-16, utilize administrative controls (limit daily noise exposure through work scheduling) or engineering controls (5ractical and economically sound methods to reduce the Sound level at its source or in employees' hearing zones). If such controls fall to reduce noise levels below those shown, personal protective' equipment must be provided and used to reduce sound within the levels indicated.

(2) If the noise level involves interruptions of 1 second or less, it is to be considered continuous.

 

When the daily noise exposure is composed of two or more periods of noise exposure of different levels, their combined effect should be considered, rather than the individual effect of each. If the sum of the following fractions C₁/T₁ + C₂/T₂…C_a/T_a exceeds unity, then, the mixed exposure should be considered to exceed the limit value. C_a indicated the total time of exposure at a specified noise level, and T_a indicates the total time of exposure permitted at that level.

 

(c) Hearing conservation program.

(1) Employers must administer a continuing, effective hearing conservation program, as described in (c) through (o) of this section whenever employee noise exposures equal or exceed an eight-hour time weighted average sound level (TWA) of 85 decibels (dB) measured on the A scale or, a dose of 50%. Employee noise exposures must be computed in accordance with Appendix A and Table G-16a without regard to any protection provided by the use of personal protective equipment.

(2) For purposes of paragraphs (c) through (u) of this section, an eight-hour TWA of 85 dB or a dose of 50% shall also be referred to as the "action level."

(d) Monitoring.

(1) The employer must develop and implement a monitoring program when information indicates that any employee's exposure may equal or exceed the action level. (i) The sampling strategy must identify employees for inclusion in the hearing conservation pro gram and enable the proper selection of hearing protection. (ii) When area monitoring is inappropriate (due to sound level variations worker mobility, etc.) representative personal sampling must be used to meet sampling requirements.

(2)(i) All continuous, intermittent and impulsive sound levels from 80-130 dB must be included in the noise measurement. (ii) Monitoring instruments must be accurately calibrated.

(3) Monitoring must be repeated whenever a change in production, process, controls or equipment occurs such that (i) Additional employees are exposed: or (ii) Hearing protection may be rendered inadequate.

(e) Employee notification. The employer must notify each employee exposed at or above the eight hour TWA of 85 dB of the monitoring results.

(f) Observation of monitoring. Employers must provide affected employees of their representatives with an opportunity to observe any measurements of employee noise exposure conducted under (d).

(g) Audiometric testing program.

(1) Employers must establish and maintain an audiometric testing program as provided for by this paragraph by making audiometric testing available to all employees whose exposures equal or exceed an eight-hour TWA of 85 dB.

(2) The program must be free to employees.

(3) (This paragraph sets the guidelines as to who may administer the audiometric tests.)

(4) All audiograms obtained must meet the requirements of Appendix C.

(5) Baseline audiograms. (i) Within six months of an employee's first exposure to noise at or above a TWA of 85 dB, employers must establish for exposed employees a baseline audiograms against which subsequent audiograms can be compared. (ii) Where mobile test vans are used to meet the requirements of (g.5.i), the employer must obtain a valid baseline audiogram within one year. Where baseline audiograms are obtained over six months after employees first exposure at or above the action level, hearing protectors must be worn for the period exceeding six months. (iii) Testing to establish a baseline audiogram must be preceded by at least 14 hours without exposure to workplace noise. Hearing protectors may be used as a substitute for this requirement. (iv) Employers must notify employees of the need to avoid high levels of nonoccupational noise exposure during the 14 hours before audiometric testing.

(6) Annual audiogram. After establishing a baseline audiogram, the employer must obtain a new audiogram for each employee exposed at or above the action level at least annually.

(7) Evaluation of audiogram. (i) Each employee's annual audiogram must be compared to that employee's baseline audiogram to determine if the audiogram is valid and if a standard threshold shift as defined in paragraph (g.l0) has occurred. This comparison maybe done by a technician. (ii) If the comparison of the audiograms reveals a standard threshold shift, the employer may obtain a retest within 30 days and use the retest results at the annual audiogram. (iii) Problem audiograms must be reviewed by the audiologist, otolaryrngologist or physician to determine the need for further evaluation. The employer must provide this person with the following information: a copy of the requirements for hearing conservation; the baseline audiogram and most recent audiogram of the employer to be evaluated; measurements of background sound pressure levels in the audiometric test room as required is Appendix D; and records of audiometric calibrations required by (h.5).

(8) Follow-up procedures. (i) If a comparison of the annual audiogram to the baseline audiogram reveals a standard threshold shift as defined in (g.l0) the employee must be informed in writing within 21 days. (ii) Unless a physician determines that the shift is not caused or aggravated by Occupational noise exposure, the employer must ensure that: employees not using hearing protection are fitted with hearing protectors, trained in their use and care and required to use them; employees already using hearing protection are refitted and retrained and if necessary provided with more effective hearing protection; the employee is referred for a clinical audiological evaluation or otological examination if additional testing is necessary or if the employer suspects that a medical pathology of the ear is caused or aggravated by wearing hearing protectors; or the employee is informed of the need for an otological examination if a medical pathology of the ear unrelated to the wearing of hearing protectors is suspected. (iii) If an employee exposed to less than an eight hour TWA of 90 dB reveals a standard threshold shift that is not persistent during subsequent audiometric testing, the employer must inform the employee of the audiometric testing results yet may discontinue hearing protector use requirements for that employee.

(9) Revised baseline. An annual audiogram may be substituted for the baseline audiogram under the following circumstances: (i) Where the standard threshold shift is persistent; or (li) Where the audiogram indicates significant hearing improvement over the baseline audiogram.

(10) Standard threshold shift

(1) As used in this section, a standard threshold shift is a change in hearing threshold relative to the baseline audiogram of an average of 10 dB or more at 2000, 3000 and 4000 Hz in either ear.

(2) In determining whether a standard threshold shift has occurred, allowance may be made for the contribution of aging to the change in hearing level by correcting the audiogram according to Appendix F.

(h) Audiometric test requirements.

(1) Audiometric tests must be pure tone, air conduction, hearing threshold examinations, with test frequencies including at a minimum 500, 1000, 2000, 3000, 4000 and 6000 slit. Tests at each frequency must be taken separately for each ear.

(2) Audiometric tests must be conducted with equipment that meets the specifications of, and is maintained and used in accordance with ANSI Specification for Audiometers, 53.61969.

(3) Pulsed-tone and self-recording audiometers must meet the requirements specified in Appendix C.

(4) Audiometric examinations must be administered in a room meeting the requirements listed in Appendix D.

(5) Audiometer calibration. (i) The functional operation of an audiometer must be checked before each day's use by testing a person with known, stable hearing thresholds, and by listening to the audiometer's output to make sure it is free from distorted or unwanted sounds. Deviations of 10 dB or more require an acoustic calibration. (ii) Audiometer calibration must be checked acoustically at least annually according to Appendix E. Test frequencies below 500 Hz and above 6000 Hz may be omitted from this check. Deviations of 15dB or more require an exhaustive calibration. (iii) An exhaustive calibration must be performed at least every two years according to the ANSI Specification for Audiometers, S3.6-l969. Test frequencies below 500Hz and above 6000 Hz may be omitted from this calibration.

(i) Hearing protectors.

(1) Employers must make hearing protectors available to all employees exposed to a TWA of 85 dB or greater at no cost to the employees. Hearing protectors must be replaced as necessary.

(2) Employers must ensure that hearing protectors are worn by all employees who: (i) Are required by paragraph (b.1) of this section to wear personal protective equipment; and (ii) Who are exposed to the action level and have either not yet had a baseline audiogram established or have experienced a standard threshold shift.

(3) Employees must be given the opportunity to select their bearing protectors from a variety of suitable hearing protectors provided by the employer.

(4) Employers must provide training in the use and care of all hearing protectors provided to employees.

(5) Employers must ensure proper initial fitting and supervise the correct use of all hearing protectors.

(j) Hearing protector attenuation.

(1) Employers must evaluate hearing protector attenuation for the specific noise environments in which the protector will be used by a method described in Appendix B.

(2) Hearing protectors must attenuate employee exposure at least to a TWA of 90 dB as required by (b).

(3) For employees who have experienced a standard threshold shift, hearing protectors must attenuate employee exposures to a TWA of 53 dB or below.

(4) The adequacy of hearing protector attenuation must be reevaluated whenever employee noise exposures increase to the extent that the hearing protectors provided may no longer provide adequate attenuation. Employers must then provide more effective hearing protectors where necessary.

(k) Training program.

(1) Employers must institute a training program for all employees who are exposed to noise at or above a TWA of 55 dB, and must ensure employee participation in the program.

(2) The training program must be repeated annually for each employee included in the bearing conservation pro-gram. Information provided in the program must be up-dated to remain consistent with changes in protective equipment and work processes.

(3) Employers must ensure that each employee is informed of the following: (i) The effects of noise on hearing; (ii) The purpose of hearing protectors, the advantages, disadvantages and attenuation of various types and instruction on selection, fitting, use and care; and (iii) The purpose of audiometric testing and an explanation of test procedures.

(l)    Access to information and training materials.

(I) Employers must make copies of this standard available to affected employees and also post a copy of it in the workplace.

(2) Employers must provide informational materials pertaining to this standard to affected employees; these materials are supplied to the employer by the Assistant Secretary.

(3) Employers must provide, upon request, all materials related to the employer's training and education program pertaining to this standard to the Assistant Secretary and the Director.

(m) Recordkeeping.

(1) Exposure measurements. Employers must maintain an accurate record of all employee exposure measurements required by (d).

(2) Audiometric tests. (i) Employers must keep all employee audiograms obtained according to (5)2 (ii) The record must include: the name the job classification of the employee; date of the audiogram; the examiner's name; date of the last acoustic or exhaustive calibration of the audiometer; the employee's most recent noise exposure assessment; and the employer must maintain accurate records of the measurements of the background sound pressure levels in audiometric test rooms. -

(3) Record retention. Employers must keep records required in (m) for at least the following periods: (i) noise exposure measurement records for two years; (ii) audiometric test records for the duration of the affected employee's employment.

(4) Access to records. All records required by this section must be provided upon request to employees, former employees, representatives designated by the individual employee and the Assistant Secretary. The provisions of (1910.20 a~) and (5-i) apply to access to records here.

(5) Transfer of records. Employers who cease to run a business must transfer all records to the successive employer and the successive employer must maintain them as outlined in (m.3).

(n) Appendices.

(I) Appendices A, Ill, C, D and E are mandatory.

(2) Appendices F, G, H and I are informational and are not mandatory.

(o) Exemptions. Paragraphs (c) through (n) are not applicable to oil and gas well drilling and servicing operations.

(p) Startup dale. Baseline audiograms required by (g) must be completed by March 1, 1984.

Appendix A - Noise Exposure Computation

This Appendix explains how to compute an employee's noise exposure amount and how to convert dosimeter readings to an eight-hour TWA average sound level.

Appendix B - Methods for Estimating the Adequacy of Hearing Protector Attenuation

This Appendix describes several methods for determining the adequacy of hearing protection attenuation for employees who have experienced a standard threshold shift.

Appendix C - Audiometric Measuring Instruments

This Appendix sets guidelines for the capabilities and use of audiometers.

Appendix D - Audiometric Test Rooms

This Appendix consists of requirements for rooms used for audiometric testing.

Appendix E - Acoustic Calibration of Audiometers

Audiometer calibration must be checked acoustically at least annually according to the procedures described in this Appendix. Audiometers must be checked for sound pressure output, linearity and tolerances.

Appendix F - Calculation and Application of Age Corrections to Audiograms

If an employer chooses to adjust the audiogram due to the contribution of aging to the change in hearing level the employer must follow the procedure described in Appendix F.

Appendix G - Monitoring Noise Levels

This Appendix gives information on noise monitoring equipment and procedures.

Appendix H - Availability of Referenced Documents

This Appendix provides a list of where employees may obtain referenced publications which have been incorporated into this standard.

Appendix I - Definitions

This Appendix consists of a list of the definitions which apply to terms found in this standard.

(b.2) Personal protective equipment. Noise attenuation devices, foot protection, shin guards, hard hats, or other personal protective clothing and equipment must be worn when hazards warrant their use. All equipment must be maintained in accordance with applicable ANSI standards and mutt be cleaned and disinfected before being used by another employee. Ear protection must conform to ANSI standards.

(c.6.ti) Handling pulp chips from railway cars & (c.7.ii) Handling pulp chips from trucks. In addition to other personal safeguards, ear protection must be provided when the noise level may be harmful.

(e.8) Barker feed. Among other requirements, ear protection equipment must be worn by the operator and others nearby if there is any possibility the noise level may be harmful. See (1910.95) above.

(C.1.vi) Personal protective devices. Provide protection against the effects of noise exposure when sound levels exceed those of Table G-16 in (1910.95), measured on the A scale of a standard sound level meter at slow response.

Section (1926.52)- Occupational Noise Exposure -in the construction standards outlines the same limits for employee exposure to noise as the general industry standard above. Employers in the construction industry are also required to utilize feasible engineering and administrative controls as the primary means of reducing excessive sound levels. However, the specific requirements of the hearing conservation amendment (1910.95.c-n) do not apply to construction.

Where personal protective equipment is necessary, section (1926.101) - Hearing Protection - requires that ear protective devices inserted in the ear be individually fitted by competent persons. Plain cotton is not considered an acceptable protective device.

The Marine Terminals standard (1917) incorporates the entire General Industry hearing conservation rule (1910.95, above).

Section (1918.95)- Longshoring Operations in the Vicinity of Repair & Maintenance Work -is concerned with noise inasmuch. as it may interfere with safe work procedures.

(a) Longshoring must not be done where chipping or scaling of decks, bulkheads or sides of vessels creates excessive noise which interferes with communication of warnings or instructions.