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What Is A Standard Threshold Shift In Hearing Loss

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What Is The Difference Between Temporary Threshold Shift And Permanent Threshold Shift

Temporary Threshold Shift | Hearing Loss & Hearing Damage | Hearing Health

The opposite of a temporary threshold shift is a permanent threshold shift. A permanent threshold shift is when the ability to hear is reduced permanently, which causes a permanent hearing loss. A professional hearing test can measure the level of the threshold shift and the results can be seen on an audiogram.

Is The Loss Persistent

If in the course of routine testing required by the Noise Standard, the STS no longer appears, it may be lined out. If the audiometric testing indicates that an STS is not persistent, the entry may be erased or lined-out . “If subsequent audiometric testing performed under the testing requirements of the 1910.95 noise standard indicates that an STS is not persistent, you may erase or line-out the recorded entry.”The employer does not have to maintain documentation concerning the removal. OSHA feels the documentation is in the hearing test records the company is already required to keep for the Noise Standard – 1910.95 . Accountability is in the audiometric record keeping.Also, The removal is not at the discretion of the reviewing professional. OSHA considers the program to be reviewed by a reviewing professional and did not want to repeat the requirement .

Additional Notes:

In recording hearing loss the requirement to check the hearing loss column on the Log for hearing loss cases has been delayed. OSHA is asking for comments concerning the need for a separate hearing loss column.Construction, agriculture, oil and gas drilling and servicing, and shipbuilding industries are not covered under 1910.95 and are not required to do hearing testing. If they do testing they would be required to log according to 1904.10 like other industries.

Does The Employee Have An Sts With Aging

A Standard Threshold Shift occurs when the current audiogram is compared to the baseline or revised baseline and a change of 10 dB average occurs at the frequencies of 2000, 3000 and 4000 Hz, and allowance has been made for aging from the presbycusis charts provided in the appendices of 1910.95 noise standard. Aging may be used in determining if an STS has occurred .For example lets consider the following hearing tests on a male worker exposed at or above the Action Level of 85 dBA TWA.


Change15 + 15 + 15 = 45 8 = 37/3= 12.3avg.

The new criteria use the baseline and revised baseline as identified in 1910.95 . This worker has an STS as defined in the 1910.95 noise standard. All the STS follow-up required by the standard is to be done. Logging criteria does not have any effect on the STS identification or follow-up required in the Noise Standard 1910.95. The employee is to be notified in writing within 21 days, hearing protection is to be fitted or refitted, recalculated for attenuation, and the wearing is to be enforced.

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Does The Current Hearing Test Exceed Normal Hearing

The hearing loss on the current hearing test must exceed the low fence criteria of 25 dB average or when the total of the thresholds at 2000, 3000 and 4000 Hz are greater than 75 . Remember, there is no allowing for age correction when determining if the retest meets the 25 dB average criteria .


Total = 6565/3 = 21.67 avg

In the above example the STS is not a possible recordable because the worker does not have a 25-dB average loss from audiometric zero. The reason for using the 25-db average is to assure that the total hearing level is beyond the normal hearing range .

OSHA feels this is consistent with the recent, January 1, 2002, record keeping rulemaking “final rule no longer requires recording of minor or insignificant health conditions that do not result in one or more of the general recording criteria such as medical treatment, restricted work, or days away form work .Lets change the thresholds,


Total = 7575/3 = 25 avg

Now the worker does have a possible recordable STS because hearing thresholds on the current test total 75 or average 25.

Causes Of Permanent Threshold Shift

Hearing Standard Threshold Shift. You Will Learn What is a ...

A permanent threshold shift can be caused by exposure to noise. Another common cause is age. We all lose our hearing as we age and hearing loss is a natural consequence of getting older. A permanent threshold shift may also occur as a result of disease, infection or drugs. It may be inherited or be a result of physical damage to the ears or to the head.

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Definition Of Temporary And Permanent Threshold Shifts

While the smallest level of TTS or PTS that can be reliably measured in an individual has not been well defined given test-to-test variability in individuals, several standards have been set for what is considered a significant hearing loss or standard threshold shift . The Occupational Safety and Health Administration states that an STS is a 10 decibel increase in hearing threshold averaged across 2000, 3000 and 4000 Hz in the same ear from an individuals baseline or recent annual audiogram . An STS is a reportable work related injury once it has been reconfirmed with a retest within 30 days of the initial test and results in a hearing threshold of at least 25 dB in the affected ear. Therefore, most occupational hearing loss or PTS is under reported since OSHA only requires an STS to be reported.

Treatment Of Permanent Threshold Shift

If you experience a permanent threshold shift, you should contact your family/doctor or an ENT to get an examination of your ears and your hearing. It is highly recommended having a hearing test taken to measure the level of the threshold shift and to see if you may need hearing aids. The results of a hearing test can be seen on an audiogram.

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What Does Permanent Threshold Shift Mean

The term permanent threshold shift refers to a permanent reduction of the sensitivity of the human ear, decreasing the ability of the ear to detect sound. In this context, the threshold is the minimum decibel level at which an individual is able to detect sound. As the human ear is more sensitive to some frequencies than others, an individuals hearing threshold is frequency-specific.

Permanent threshold shifts are colloquially be referred to as hearing loss. When they occur due to excessive noise exposure, they are referred to as Noise-Induced Permanent Threshold Shifts. Occupational exposure to excessive noise is one of the main causes of PTS.

The higher the hearing threshold, the louder a noise must be for an individual to detect it. As such, hearing loss is described as an increased or positive threshold shift, while improvements in hearing are referred to as decreased or negative shifts.

Safeopedia Explains Standard Threshold Shift

Hearing Loss

Loud noise can lead to hearing loss. When working in high-level noise, ear protection is key. As per a report from the National Institute for Occupational Safety and Health , there are nearly 22 million workers in the United States who had to work in high-level hazardous noise, and approximately $242 million in compensation has been paid for hearing loss disability every year. That is why hearing loss is the most common occupational illness in the U.S.

There are different types of Hearing Protection Devices available such as earmuffs and earplugs. According to WMA, it has become necessary to use earplugs and earmuffs in high-decibel-producing areas to avoid STS and in turn protect the ears from hearing loss.

Earmuffs are a very stylish ear protection device typically designed for both ears with a headband. They are made of a high-quality, sound-absorbing material like foam. Earplugs are also a stylish HPD, and they’re designed to fit in your ear canal. There are many kinds of earplugs available, which are detailed below:

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How Do You Calculate Standard Threshold Shift

A threshold shift of 20 dB exists at 4000 Hz between the audiograms taken at ages 27 and 32. . A retest audiogram has confirmed this shift.

Likewise, what is a standard threshold shift?

A Standard Threshold Shift, or STS, is defined in the occupational noise exposure standard at 29 CFR 1910.95 as a change in hearing threshold, relative to the baseline audiogram for that employee, of an average of 10 decibels or more at 2000, 3000, and 4000 hertz in one or both ears.

Also Know, what is a permanent threshold shift? A permanent threshold shift is a permanent shift in the auditory threshold. It may occur suddenly or develop gradually over time. A permanent threshold shift results in permanent hearing loss.

Subsequently, question is, is a standard threshold shift recordable?

The OSHA noise standard defines a STS as an average 10dB or more loss in one or both ears relative to the most current baseline audiogram averaged at 2000, 3000 and 4000 Hz. This is not an OSHA recordable hearing loss.

How do Audiograms work?

An audiometry exam tests your ability to hear sounds. Sounds vary, based on their loudness and the speed of sound wave vibrations . Hearing occurs when sound waves stimulate the nerves of the inner ear. The sound then travels along nerve pathways to the brain.

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What Are The Characteristics Of Permanent Noise

The main characteristics of noise-induced hearing loss are:

  • Noise exposure can result in a permanent hearing loss that may affect speech communication.
  • Noise-induced hearing loss is a cumulative process: factors that determine hearing loss include the overall noise levels, the composition of the noise, the exposure time over a typical work day, and the worker’s work history .
  • Noise-induced hearing loss occurs randomly in exposed persons.
  • Some individuals are more susceptible to noise-induced hearing loss than others.
  • Permanent hearing loss is caused by damage to certain inner ear structures â these structures cannot be replaced or repaired.
  • At a given level, low-frequency noise ) is less damaging compared to noise in the mid-frequencies .
  • In the initial stages, noise-induced hearing loss is most pronounced at 4000 Hz but it spreads over other frequencies as noise level and/or exposure time increases.

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How Is Hearing Loss Measured

Hearing loss is measured as threshold shift in decibel units using an audiometer. The 0 dB threshold shift reading of the audiometer represents the average hearing threshold level of an average young adult with disease-free ears. The PTS , as measured by audiometry, is dB level of sounds of different frequencies that are just barely audible to that individual. A positive threshold shift represents hearing loss and a negative threshold shift means better than average hearing when compared with the standard.

Audiometric testing is usually done annually. By comparing an individual’s results from year to year, changes can be detected, often before the individual notices any change themselves.


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Presentation On Theme: Hearing Standard Threshold Shift Presentation Transcript:


1 Hearing Standard Threshold Shift

2 You Will Learn What is a Standard Threshold Shift?How is a Standard Threshold Shift calculated?What is an employer required to do in Washington State?

3 Abbreviation This presentation will use the abbreviation STS to meanStandard Threshold Shift

4 What Is A Standard Threshold Shift?A Standard Threshold Shift is a significant change in hearing ability .Over time, with enough threshold shift, a person will have great deal of trouble understanding speech.

5 DefinitionThe Standard Threshold Shift definition in the Hearing Loss Prevention Rule, WAC is:A hearing level change, relative to the baseline audiogram, of an average of 10 dB or more at 2000, 3000, and 4000 Hz in either ear.

6 More DefinitionsdB means decibel, a unit of sound measurement. Often called loudness.Hz means Hertz, ameasurement of frequency.Often called pitch.

7 What Is An Audiogram?Before being first exposed to excessive noise, an employer is required to provide hearing tests or audiograms to employees, which is called a baseline.Subsequent hearing tests are compared to the original baseline audiogram.Note: Employers who use mobile testing units are allowed up to one year to obtain a valid baseline audiogram for each exposed employee. The employee must still be given training and hearing protection.

8 What Is An Audiogram?An audiogram is a picture or graph of a hearing test.It measures the quietest sounds you can hear at different frequencies.

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What Is Osha Shift

OSHA considers a normal work shift to last a period of no more than eight consecutive hours for five days of the week with at least an eight-hour rest period between shifts. Shifts that last longer, have less rest periods or cover more than five shifts in a week are considered an extended or unusual shift, according to OSHA.

Is The Hearing Loss Work

Where it is true that noise exposure below the Action Level of 85 dBA TWA has a small percentage of workers at risk, it is important to note that in my experience the occurrence of work-related hearing loss without noise is rare in most industries. A ruptured eardrum due to trauma or diving, sparks in the ear, etc., would already be recordable as an injury. Exposure to heavy metals and organic solvents as toluene, xylene, styrene, trichlorethylene, etc. may produce hearing loss without noise. However, their occurrence without noise is rare. Hearing testing on some routine basis of non-noise exposed workers is strongly encouraged. The benefit of a continuing, successful hearing conservation program is to maintain a healthy workforce by detecting and preventing hearing loss in all workers.

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What Is A Standard Threshold Shift

When it comes to hearing loss, a Standard Threshold Shift is a 10 dB deterioration of the average of thresholds at 2000, 3000, and 4000 Hz when comparing the baseline for each ear to the most recent test. Age correction may be permitted depending on the state where the testing is taking place. When an STS is identified, the employee must be notified in writing within 21 days. If an STS is present and the average hearing level at 2000, 3000, and 4000 Hz is equal to or greater than 25 dB, then it should be recorded on the OSHA 300 Log. The employer has 30 days to perform the recommended retest, but ideally it should not be performed on the same day as the original test that reported the STS due to potential transient issues impacting hearing.

After the completion of the retest, and confirmation by a qualified hearing healthcare professional that a work-related STS has occurred, the employer has seven days to record the shift on the OSHA 300 Log. If the retest does not confirm the STS, then no recording is necessary. And if a retest is not performed, the STS is automatically confirmed and is required to be logged within 30 days of the original test. If a subsequent test shows that the recorded STS is no longer present, it can be repealed from the OSHA Log.

  • obtaining new dosimetry or measurement of noise exposure for the employee
  • investigating noise control mitigation options
  • fit-testing of hearing protection

Safeopedia Explains Permanent Threshold Shift

Hearing Conservation

Occupational PTS can be caused by either chronic or acute exposures to loud noises . Noise exposure causes PTS by damaging the hair cells in the inner ear that are responsible for detecting and transmitting sound. This type of damage is referred to as acoustic trauma. The cochlea is most sensitive to damage from higher frequency noises.

As humans tend to naturally lose hearing over time, a PTS may not be considered a sign of acoustic trauma or excessive noise exposure unless the increase in hearing threshold reaches a certain level of significance. In the United States, OSHAs standard for significance is a 10 decibel increase in hearing threshold, averaged across 2000, 3000, 4000 Hz frequency thresholds . This 10-decibel decrease is referred to as a standard threshold shift OSHA requires any STS to be reported as a workplace injury.

Because PTS cannot be reversed, occupational safety authorities require employees to be provided with hearing protection that is sufficient to protect against long-term damage. OSHA permits exposures of 85 dB for 16 hours per day for every 5 dB increase above 85 dB, the allowed exposure time is reduced by half . If employees are exposed to an 8-hour time-weighted average of at least 85 dB per-day, the employer must implement a hearing testing program to monitor employees for threshold shifts.

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An Explanation Of Recording Hearing Loss On The Osha 300 Log

In January 2001, OSHA published rules on recording and reporting occupational injuries and illnesses and made the effective date January 1, 2002. They delayed the recording criteria for cases involving occupational hearing loss and musculoskeletal disorders until January 1, 2003, and asked for comments. On July 1, 2002, OSHA published the finalized criteria for recording hearing loss. As of January 1, 2003, hearing tests meeting the following finalized criteria of change were required to be logged on the OSHA 300 form. All states are required to use identical recording criteria .

1904.10 Recording criteria for cases involving occupational hearing loss.

Basic requirement. If an employees hearing test reveals that the employee has experienced a work-related Standard Threshold Shift in hearing in one or both ears, and the employees total hearing level is 25 decibels or more above audiometric zero in the same ear as the STS, you must record the case on the OSHA 300 Log.

RE: Federal Register/Vol. 67, 126/ Monday, July 1, 2002/Rules and Regulations pg 4407The following is a step by step approach in considering if an employee meets the recording criteria and when a previous entry may be erased or lined-out.

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