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Hearing Conservation

Risk Management & Safety Department


Table of Contents

    ACGIH has established exposure guidelines for occupational exposure to noise in their threshold limit values (TLVs).

    TLV/BEI Resources.

    US Department of Transportation (DOT), Federal Motor Carrier Safety Administration

    49 CFR 393.94, Vehicle Interior Noise Levels 

    Environmental Protection Agency (EPA)

    40 CFR 211, Product Noise Labeling

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    4.0 PURPOSE

    The purpose of this program is to prevent hearing loss due to noise and protect BYU employees and students from noise exposure .  This program is also intended to assist BYU departments with improving their work areas through noise reduction and control.

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    5.0 SCOPE

    This Program applies to all BYU employees who are exposed to occupational noise levels at or exceeding an 8-hour time-weighted-average of 85 decibels or any Threshold Limit Value (TLV) listed in Table 1 (based on a 3 dB equal energy exchange rate and represented on the A scale (dBA)).   Employees who are exposed to average noise levels equal to or above the TLVs must be included in BYU’s Hearing Conservation Program (HCP).  Employees exposed to noise levels below the TLVs may be included in BYU's Hearing Conservation Program (HCP) with approvals from their supervisor, BYU's Audiology Clinic Director or BYU's Hearing Conservation Program Administrator.

    No exposure of an unprotected ear to noise levels in excess of a C-weighted peak sound pressure level of 140 dB is permitted.


    Table 1 

    TLVs for Noise

      Duration/Day Sound Level dBA
    Hours 24 80
      16 82
      8 85
      4 88
      2 91
      1 94
    Minutes 30 97
      15 100
      7.5 103
      3.75 106
      1.88 109
      0.94 112
    Seconds 28.12 115
      14.06 118
      7.03 121
      3.52 124
      1.76 127
      0.88 130
      0.44 133
      0.22 136
      0.11 139


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    Follow the following diagram or see the step-by-step instructions below the diagram.


    hcp flowchart


    Step 1

    Determine whether or not your employees are exposed to high or questionable noise levels.  This might be in your specific area or different areas across campus. 

    Step 2

    If you determine that your employees encounter high noise levels or if you need assistance measuring noise levels in your area, submit a Noise Survey Request Form or call BYU's Hearing Conservation Program Administrator at 422-2943 or the Risk Management & Safety Department at 422-4468.  See details in Appendix B Noise Exposure Assessments.

    If the noise exposure levels have already been assessed for your area or position, skip to Step 3. 

    Step 3

    For work environments where noise exceeds TLVs, to the extent feasible, engineering controls, equipment maintenance, administrative controls and work practices should be used to lower noise levels as much as is possible.

    Employees with exposures equal to or exceeding TLVs must be included in BYU's Hearing Conservation Program.  This includes:

    • Annual Training
    • Baseline(initial) audiometric test conducted as soon as possible after date of hire)
    • Annual audiometric testing
    • Appropriate hearing protection devices(HPD) provided by employer
    • Encourage employees to wear HPDs

    Step 4

    Contact BYU's Hearing Conservation Program Administrator at 422-2943 for training classes or sign up for available classes on the Risk Management Training Calendar. 

    Step 5

    If your area has noise levels that exceed the TLV or other noise problems and you wish to, contact the Hearing Conservation Program Administrator to assist with evaluations, engineering control design and verification of controls.

    Area and personal noise exposure data is maintained by the Industrial Hygiene division of RM&S. Audiometric test results are maintained by BYU's Audiology Clinic. Employees can request to review records or obtain copies of their noise exposure data and audiometric tests from Risk Management & Safety Department (422-4468) and the Audiology Clinic (422-7758), respectively.

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    Department Heads, Managers, Supervisors, and Principal Investigators:

    • Provide work environments that minimize noise to the greatest extent reasonable

    Buy Quiet Program for equipment purchases

    Make Quiet, existing processes as much as is feasible

    Maintain Quiet through proper equipment maintenance

    • Provide adequate hearing protective devices (HPDs) for employees who are exposed to noise levels equal to or above the limits established in BYU's Hearing Conservation Program (HPDs can also be provided for comfort in situations where noise levels are bothersome, but do not exceed program limits)
    • Supervise the employees use of HPDs in required areas or when performing tasks that require them
    • Do not allow employees to use personal stereo headsets in lieu of hearing protection devices
    • Request that Risk Management & Safety Department evaluate noise exposures and noisy operations
    • Ensure that employees who will work in areas where they are exposed to noise levels which exceed limits established in this program are appropriately trained, provided with personal protective equipment and provided with audiometric exams (baseline, annual, follow-up and exit [See Appendix B Noise Exposure Assessments for definitions])
    • Ensure that employees who experience a standard threshold shift are assigned to wear HPDs and trained in their use and care or refitted if already wearing HPDs


    • Wear approved hearing protective devices correctly in posted noise hazard areas or when performing tasks which require the use of HPDs
    • Maintain hearing protectors in sanitary condition and proper working order
    • Report noise hazards and HPD problems to the appropriate supervisor, department representative or Risk Management & Safety
    • Do not use Personal stereo headsets in lieu of hearing protection devices

    Risk Management & Safety's Hearing Conservation Program Administrator:

    • Monitor work sites for noise levels and inform employees and supervisors of results
    • Recommend appropriate engineering and administrative noise control measures
    • Assist employees in selection of proper protective devices and provide instruction on their use
    • Provide training and information regarding noise hazards and hearing conservation
    • Provide assistance with purchasing quiet equipment and developing engineering controls
    • Post areas known to present noise hazards with signs requiring the use of hearing protectors while in such areas

    Audiology Department:

    • Provide baseline, annual, follow-up and post-employment audiometric exams
    • Evaluate audiometric exams
    • Communicate any identified standard threshold shifts to the employee, his or her supervisor, and Risk Management & Safety
    • Establish any work restrictions necessary to prevent additional hearing loss

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    All employees who fall within the scope of this program must receive initial hearing conservation training and annually thereafter as long as they are working in areas where they may be exposed to noise levels that exceed limits stated in this program.

    Training Outline:

    Anatomy and function of the ear

    Types of hearing loss

    Types of hearing protectors and proper usage

    Statistics on occupational hearing loss

    Basic concepts and terms relating to sound pressure level

    Activities related to non-occupational hearing loss

    Elements of BYU’s Hearing Conservation Program

    To schedule a training class, contact the Hearing Conservation Program Administrator at 422-4468.

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    Employees who fall within the scope of this program will be monitored to ensure that they are participating in annual training and attending annual audiometric evaluation. 

    The number of employees who are trained annually shall be tracked and submitted by department to the Compliance Committee. 

    Follow-up on employees with verified Standard Threshold Shifts.

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    Appendix A

    Audiometric Testing

    What is Audiometric Testing?
    When an employee is enrolled in the BYU Hearing Conservation Program, he or she must complete baseline, annual, and post-employment audiometric tests. Audiometric tests can be scheduled by calling BYU’s Audiology Clinic at 422-7758. The Audiology Clinic is located in room 136 of the John Taylor Building.
    When an employee has a substantiated Standard Threshold Shift, the Audiology Clinic will communicate the information to the Industrial Hygiene Officer (IHO) of Risk Management and Safety. The IHO will pass the information to the Safety Director of RMS so that the injury can be indicated on the OSHA 300 log. Additionally, if any of the conditions listed in Appendix I Problem Audiograms which need Professional Review, the employee shall be allowed to see an appropriate professional for evaluation. Action will be taken by the IHO to assess the employee's work environment and make recommendations for controlling noise generated at the work area in question.

    It is the responsibility of the supervisor of employees that fall within the scope of BYU's HCP to arrange for the employee's audiometric exams. The cost of the test is covered by the employee's department and is free to all employees enrolled in the Hearing Conservation Program.
    To ensure accuracy, the audiometric test should be preceded by at least 14 hours without exposure to workplace noise. This will reduce the potential for the employee to be suffering from a temporary threshold shift, which would result in an incorrect evaluation of the employee's hearing threshold. Hearing protection may be used to provide the pre-test exposure control, providing its use is well supervised.

    Baseline Audiograms  Everyone enrolled in the Hearing Conservation Program must undergo testing to establish a baseline audiogram and to determine the person’s “hearing threshold” and against which to compare subsequent audiograms. It is preferable to obtain the baseline audiogram before the employee begins work in noisy areas, However, 1910.95, OSHA's Occupational Noise Exposure Regulation, requires the baseline to be done within 6-months of the employee's first exposure at or above the action level for noise.

    Annual Audiogram  A new audiogram is obtained at least annually for each employee exposed at or above the time-weighted average of 85 dBA. It is important to ensure that employees are protected from workplace noise proper to the audiometric test in order to obtain a valid measurement.

    Post-Employment Audiogram  Post-employment audiograms must be completed when an employee leaves the job or workplace where he or she is no longer routinely exposed to noise level at or above an 8-hour time-weighted average of 85 dBA. It is the responsibility of the employee and the supervisor to complete a post-employment audiogram.

    Evaluation of the Audiogram  An audiologist will evaluate audiometric test results and schedule any necessary follow-up evaluations. When medical personnel identify an employee with a significant threshold shift or a baseline audiogram showing early indications of hearing loss (i.e., an existing hearing level of 25 dB or greater between 500 and 4000 Hz, according to ANSI s3.6-1969), this information will be provided to Risk Management & Safety Department, so the appropriate hearing conservation and training activities can be initiated to reduce the potential for further hearing loss. The employee will be notified of these results in writing within 30 days. At this point the employee will need to be retrained regarding the hazards and precautions of working in noisy environments. Other modifications to the workplace may also be needed to reduce noise exposures to prevent additional hearing loss.

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    Appendix B

    Noise Exposure Assessments

    Noise exposure is described either in terms of an 8-hour time-weighted average sound level or a noise dose (in percent at the 8-hour allowable exposure).

    Employee exposure to occupational noise should be maintained within the limits outlined in Table 1.

    When employee exposure to occupational noise is expected to equal or exceed an 8-hour time-weighted average of 85 dBA, or equivalently, a dose of 50 percent or greater, the employee must be included in an effective hearing conservation program as outlined in this document.

    Exposure Monitoring
    RM&S performs noise exposure monitoring of faculty, staff, and students who may be exposed to noise over OSHA's 85-decibel dBA action level on an eight-hour time-weighted average basis. Personal or area noise monitoring is conducted to identify employees and students for inclusion in the Hearing Conservation Program and to enable the proper selection of hearing protectors. Area noise monitoring is also used to identify campus locations where average noise levels exceed OSHA's 90 dBA permissible exposure limit. These are areas where hearing protection should always be worn. Employees or their supervisors should contact RM&S to schedule noise monitoring if they suspect exposures to excessive noise on the job, or if previously monitored noise levels may have changed due to modifications to equipment or processes. RM&S should also be contacted to schedule monitoring if the hearing protectors in use are suspected of being inadequate. If desired, employees or their representatives may observe the noise monitoring procedure by arranging with RM&S prior to the date of the monitoring. Evaluations of employee exposure are recorded and printed via the noise dosimeter. The report allows for the documentation of all necessary information including name of employee, job classification, employee number; date, location, and results of measurements; and description of the noise measurement equipment and calibration information. Persons whose noise exposures have been monitored will receive written notification of their exposure monitoring results from RM&S. Persons whose eight-hour time-weighted average noise exposure exceeds the action level will be enrolled in the Hearing Conservation Program. These individuals will be offered audiometric testing, will have hearing protectors made available to them, and will be provided training on the fitting, use, and care of these devices. Persons whose eight-hour time-weighted average noise exposure is less than 85 dBA will not be enrolled in the campus Hearing Conservation Program, and generally do not require audiometric testing, training, or the use of hearing protectors. Additional monitoring of their personal noise exposures should not be required unless a significant change is perceived in the workplace noise level.

    Preliminary Noise Survey

    A preliminary noise survey consists of a "walk-through" of all facility areas with a sound-level meter to identify operations or areas where employees may be exposed to hazardous noise levels. A facility layout or grid of plant areas may be useful for recording noise levels and identifying areas that require further study. While this study is intended as an overview of noise exposure, consideration should include variations in noise levels due to shift changes, operation of noise-generating equipment, or other factors that could affect baseline levels.
    Where information indicates that employees in that area may be exposed to noise levels equal to or greater than 50 percent of the permissible exposure (e.g., 85 dBA over eight hours), more specific measurements should be obtained.

    Detailed Noise Survey
    The data gathered in the preliminary noise survey will determine which locations require more study. The detailed noise survey will:

    Use a noise dosimeter to provide specific information of the noise levels at individual workstations

    Evaluate time-weighted average employee exposure

    Define areas where noise exposure may exceed permissible levels and should be designated as a noise hazard area, which requires the use of hearing protection

    Determine which employees should be included in the Hearing Conservation Program and receive audiometric testing


    In this study, measurements are recorded as close as practical to the employee’s workstation at approximated ear level.
    Impulse noise shall be integrated with noise exposure assessments. Impulse noise exposure levels shall not exceed 140 decibels (dB).

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    Appendix C

    Noise Controls

    Employee exposure to occupational noise can is controlled as much as technologically and economically feasible by applying engineering principles that reduce noise levels. They may include:

    Quieter machinery

    Quieter processes

    Reduction of noise transmission

    Isolation of equipment or equipment operator

    Proper maintenance of machinery and equipment

    Purchasing procedures that specify criteria for maximum noise levels

    Administrative controls are also applied, when feasible. They may include:

    Rotation of employees to limit exposure times

    Flexible machinery operation schedules to limit exposures

    Work task arrangements that reduce the time an employee must spend in a noisy area


    Where engineering and administrative controls are not feasible or during the evaluation and implementation of such controls, personal hearing protective equipment is used to protect employees from excessive noise exposure. This protection is provided as one part of an effective hearing conservation program.

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    Appendix D

    Hearing Protection Devices

    A hearing protection device (HPD) is a personal safety product that is worn to reduce the harmful auditory and/or annoying effects of sound. HPDs are often a last resort, when other means such as engineering controls or removal of the person from the noisy environment are not practical or economical.

    History: Research and development in hearing protection began during and following World War II in response to the tremendous hearing loss caused by military operations. Hearing conservation programs and use of hearing protection in the military and industry followed in the early 1950s. In 1983 OSHA introduced the Hearing Conservation Rule.

    HPDs must be utilized by BYU employees when they may be exposed to noise levels equal to or exceeding an 8-hour average of 85 dBA, if a short term exposure is equivalent to an 8-hour 85 dBA exposure, or who enter into areas posted or otherwise indicated as HPD required areas. HPDs may also be provided for short-term control of noise based on comfort, irritation, etc., as long as the use of HPDs does not create a significant safety hazard due to the decrease in hearing ability. When HPDs are required, a choice of several types of hearing protectors must be available to employees who are exposed to noise levels equal or above limits listed in this program.

    HPD's ability to reduce noise is measured as its Noise Reduction Rating (NRR). The greater the NRR, the better the noise attenuation. The NRR must be derated for accuracy. Derating the NRR by 50% is the current method for this (for example, and NRR of 30 dB would be reduced to 15 dB). The NRR is usually listed on the hearing protector's box. RM&S can help determine appropriate types of hearing protectors for specific situations, and can provide training on the proper use of hearing protectors.

    Types of Hearing Protectors

    Earplugs (Aural): Plug-type protectors that fit directly into the ear canal

    "Rolldown" Foam



    Custom molded

    Semi-Insert (Soft pods or tips that are held in place by a lightweight spring-loaded band)

    Earmuffs (Circumaural): Plastic domes that cover the ears and are connected with a spring band that fits on top of the head or attached to a hardhat

    Noise Canceling Ear Muffs

    There are a couple of issues that should be considered before selecting this type of HPD.

    1. The active (noise cancelling) components only work at relatively low frequencies (up to 700 - 1000 hz). Most industrial noise has a significant component above that range where the active aspect of the devices is nil.  That means that the only active HPD that should be allowed are fully circumaural (fit completely around the pinna) so that the passive aspect of the earmuff blocks these higher frequency sounds. These sorts of HPD are produced by several manufacturers, including David Clark, Noisebuster, Sennheiser, Bose and others. The optimal application for these devices is in steady state predominantly low frequency noise - general aviation pilots love them.

    2. Most consumer grade devices, like the Bose Sanctuary and the devices available at the big box electronic stores are supraural - they rest on the pinna, and do not enclose it. They are not suitable for industrial use since they essentially offer no protection above the "cut off" range of the electronics.

    3. Most circumaural devices have been evaluated under ANSI S3.19 and bear an NRR; these devices are approved for industrial use, but the active aspect of the protection is not considered. The NRR on these is based on the passive performance, without the electronics engaged.

    4. ANSI working group S12/WG11 has on its' agenda the development of a standard to evaluate the active aspect of these devices that (hopefully) will be included in the new HPD evaluation rule due from EPA by the end of 2006, but for now, there is no standardized way to assess the protective performance of the electronics.

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    Appendix E

    Personal/Portable Stereos (mp3, cassette, radio, etc.)

    Personal/Portable stereo headphones must never be used for hearing protection devices. They do not protect from loud noise levels and usually the stereo sound level must be increased above background noise level (Remember the level requiring Hearing Protection Devices in the first place) resulting in even more noise exposure.


    Is it possible that listening to a personal music device could impact your current and future hearing ability?  How do you know?  See the following study for more information:  How loud is that portable music device (2004 Study)

    Abstract of Study

    Appendix F

    Noise Levels and Exposure Limits

    Noise Source Decibel Level
    Grand Canyon at night, no birds, no wind 10
    Whisper 30
    Normal conversation/laughter 50-70
    Dishwasher 54-85
    Vacuum cleaner 62-85
    Hair Dryer 59-90
    Food Disposal 57-93
    Gasoline Powered Push Lawn Mower 87-93
    Average Motorcycle (Noise from wind is excluded) 90-110
    Air Compressor 87-93
    Leaf Blower 95-105
    Circular Saw 100-105
    Maximum Output of Stereo 100-120
    Chainsaw 100-110
    Average Snowmobile 100-120
    Average Fire Cracker 120-140
    High Powered Car Stereo with Subwoofer 110-140
    Average Rock Concert 120-140


    Duration Without Hearing Protection

    Sound Level dBA

    24 Hours


    16 Hours


    8 Hours


    4 Hours


    2 Hours


    1 Hour


    30 Minutes


    15 Minutes


    7.5 Minutes


    3.75 Minutes


    1.88 Minutes


    0.94 Minutes


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    Appendix G


    Action level
    The level of noise exposure at which: 

    • An employee must be enrolled in the Hearing Conservation Program and provided audiometric testing
    • Representative noise exposure monitoring is required by RM&S 
    • Hearing protectors and training on noise hazards must be provided to the employee
    • OSHA has set the current action level at 85 A-weighted decibels, or dBA, over an eight-hour period.

    Audiometric testing
    Exams that measure the sensitivity of a person's hearing threshold in decibels. The testing also establishes a baseline hearing threshold that is compared to later exams to determine if hearing loss has occurred.

    Baseline Audiometric Exam
    Ideally this should be done as soon as the employee is hired or prior to the employee's first work assignment in an area with high noise levels which exceed limits established in this program (OSHA requires that baseline audiograms be preceded by 14 hours without any unprotected noise exposure)

    Annual Audiometric Exam
    Annual exam as long as employee is working in area with levels which exceed limits established in this program

    Follow-Up Audiometric Exam
    Follow-up exams are required within 30 days if a hearing threshold shift or other problems(See Appendix F) are detected in the annual or baseline exam

    Post Employment Exam
    Audiometric exam taken prior to employee leaving the university if their annual exam is more than 6 months old

    Decibel (dB)
    The standard unit used to measure sound level. The decibel scale is logarithmic.

    An A-weighted decibel scale. The A-weighting curve is an approximation of equal loudness perception characteristics of human hearing for pure tones relative to a reference of 40 dB sound pressure levels at 1 kHZ (i.e. the 40-phon curve).

    The entire hearing apparatus, consisting of three parts: external ear, the middle ear or tympanic cavity, and the inner ear.

    Hertz (HZ)
    The unit of measure for noise frequency in cycles per second. (1 cycle/ second = 1Hz)

    Noise reduction rating (NRR)

    A measure of the noise reduction that a given hearing protective device provides.

    Noise Dosimeter
    A sound level meter that is body worn with a microphone that can be placed in the vicinity of the wearers hearing zone.  The SLM measures pressure changes and computes and logs desired noise measurements. 

    Any unwanted sound.

    Noise-induced hearing loss

    Slowly progressive inner-ear hearing loss resulting from exposure to continuous noise over a long period of time, as contrasted to acoustic trauma or physical injury to the ear.

    Nonauditory effects of noise
    Stress, fatigue, health, work efficiency, and performance effects of loud, continuous noise.

    The interval between two sounds having a basic frequency ratio of two.

    Permissible Exposure Limit (PEL)
    The maximum legal noise exposure, established by Cal/OSHA. The current PEL is 90 dBA over an eight-hour period.

    Hearing loss attributed to the aging process.

    Rock and Roll

    Noise to some and music to others.

    An oscillation in pressure, stress, particle displacement, particle velocity, and so on, propagated in an elastic material, in a medium with internal forces; or the superposition of such propagated oscillations. Also the sensation produced through the organs of hearing usually by vibrations transmitted in a material medium, commonly air.

    Sound Absorption
    The change of sound energy into some other form, usually heat, on passing through a medium or striking a surface. Also, the property possessed by materials and objects, including air, or absorbing sound energy.

    Sound Absorption Coefficient

    The ratio of the sound energy absorbed by the surface of a medium or material exposed to sound to the sound energy incident on that surface.

    Sound Level Meter
    An instrument designed to measure sound pressure levels in decibels referenced to 0.0002 microbars.

    Sound Pressure Level
    The level in decibels, of a sound is 20 times the logarithm to the base 10 of the ratio of the pressure of this sound to the reference pressure, which must be explicitly stated.

    Speech Interference Level (SIL)
    The average, in decibels, of the sound-pressure levels of a noise in the three octave bands of frequency: 600-1200, 1200-2400, 2400-4800Hz.

    Standard Threshold Shift (STS)
    A change of 10 decibels or more in the average of hearing thresholds at the audiometric test frequencies of 2, 3 and 4 kHz in either ear when the current audiogram is compared to the baseline with age corrections applied.

    Sounds heard within the head in the absence of actual sounds in the environment. Tinnitus can be experienced in many forms, such as ringing, hissing, whistling, buzzing, or clicking. There are many causes, but hearing loss and age have been are significant with hearing loss being more significant.

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    Appendix H

    Loudness Comparison Diagram

    Loudness Diagram/Comparison

    noise comparison chart


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    Appendix I

    Human Ear Diagram

    Human Ear Diagram

    ear image

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    Appendix J

    Problem Audiograms Which Need Professional Review

    Baseline audiograms showing significant pre-existing hearing loss


    Significant threshold shifts which do not constitute OSHA STS, including precursor shifts at STS frequencies as well as shifts at other audiometric frequencies

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    Appendix K

    Internet Resources

    Hearing Animation and How we Hear
    Ear Animation
    Dangerous Decibels
    NIH NIDCD Wise Ears
    Health Central Ear, Hearing and Audiology Information
    Diagrams of the ear and hearing mechanism

    How loud is that portable music device (2004 Study)

    Abstract of Study

    Supersonic jet when do you see it


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Content date: 1 January 2012
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