Hearing Tests

An audiometric test shows an individual's hearing threshold levels as a function of frequency. Results are shown on a chart, graph or table called an audiogram.

Within six months of an employee's first exposure to sound levels at or above the action level, the employee will have a baseline audiogram performed. Before the test, the employee must go without exposure to workplace noise for at least 14 hours (hearing protectors can be used to help meet this requirement).

The baseline will establish a standard against which subsequent audiograms can be compared. This will help determine if the employee is showing any signs of hearing loss.

Affected employees must get a new audiogram at least annually after having the baseline one done.

Audiograms will be evaluated against the baseline to determine if a Standard Threshold Shift (STS) has occurred. An STS is a change in hearing threshold, relative to the baseline audiogram, of an average of 10 dBs or more at 2000, 3000, and 4000 Hz in either ear.

If an employee's annual audiogram shows an STS, then the employer can have the employee re-tested within 30 days.

Audiograms that indicate problems must be reviewed by a hearing professional or physician, who must determine if there is a need for further evaluation. The employer must supply the professional or physician with relevant information.

If an STS has occurred, the employee must be notified of this in writing within 21 days of the determination.

Unless a physician determines that the STS is not work related or aggravated by occupational noise, then the employer must:

• Fit employees that are not using hearing protectors with them, provide training on their use and care, and require their use.
• Refit and retrain employees that are using hearing protections, providing hearing protectors that offer greater noise reduction (called attenuation) if necessary.

The employer must also refer the employee for a clinical audiological evaluation or otological exam (ear exam), as appropriate, if additional testing is necessary, or if the employer suspects that a medical issue with the ear is caused or aggravated by wearing hearing protectors.

The employee must also be informed of the need for an otological exam if a medical issue with the ear that is unrelated to the use of hearing protectors is suspected.

If subsequent audiometric testing indicates that an STS is not persistent, the employer must inform the employee of the new audiometric interpretation and can discontinue the required use of hearing protectors for that employee.

A baseline audiogram can be updated with an annual audiogram, if the hearing professional or physician decides that the STS is persistent or the hearing threshold in the new audiogram indicates significant improvement over the baseline.

To learn more about Hearing Protection visit our Hearing Protection Online Training web page.