Ch. 8: Classification of Single & Periodic Tests Part B

Question 1

What criteria are used to classify periodic test results as AbS?

Answer 1

• Periodic test results are classified as AbS when they are compared to the baseline results and indicate a loss of at least 15 dB at two consecutive frequencies from 1000 up to and including 6000 Hz.
• The loss can be in one or both ears.

Question 2

When is a periodic test result classified as NS?

Answer 2

Any periodic test result that is not AbS (abnormal shift) is classified as NS (no shift).

Question 3

Which periodic test results should be referred to an audiologist or physician?

Answer 3

Periodic test results classified as AbS (abnormal shift) should be sent to an audiologist or physician for review.

Question 4

What criteria are used to determine when to adjust the baseline and make a periodic test a reporting baseline?

Answer 4

• A periodic test is established as the reporting baseline (or new baseline) when two consecutive periodic tests are classified AbS and the second periodic test reveals equivalent or greater shifts.
• The first periodic test characterized as AbS becomes the new baseline.
• Subsequent periodic tests are compared to the new baseline until a further baseline adjustment is done.

Question 5

What are sloping patterns?

Answer 5

• The sloping pattern is one of the most common audiometric patterns seen in workers exposed to noisy environments.
• This pattern can also be caused by factors other than noise, such as viral infections.
• It is characterized by a decrease in hearing threshold levels at 3000, 4000, or 6000 Hz in either ear.

Question 6

What are sloping patterns with a notch?

Answer 6

• This test shows a sloping pattern with a notch of 30 dB at 3000 Hz.
• Discuss the use of hearing protection with the worker and ensure he knows how to fit it properly.
• Typical in NIHL where hearing is improved and lower and higher frequencies.
• The notch in this audiogram occurs at 4000 Hz in the left ear and 6000 Hz in the right ear.

Question 7

What are sloping patterns with no notch?

Answer 7

• Another common pattern is the high frequency drop with no notch.
• This effect is often due to presbycusis (hearing loss that accompanies aging), but it can also be caused by noise, disease, genetics, ototoxic drugs, or a combination of these factors.
• Loss in the mid-frequencies can be a result of long-term noise exposure.
• An audiogram may show a notch at the higher frequencies in the early years of noise exposure, but the notch may no longer be evident in later years due to aging.

Question 8

What are rising patterns?

Answer 8

• Rising patterns are the type of audiogram that shows hearing threshold levels that improve at the higher frequencies and is not usually caused by noise exposures.
• These patterns generally indicate conductive or sensorineural loss due to some form of pathology, such as Meniere’s disease.
• This is an abnormal audiogram showing a rising pattern with low frequency hearing loss.

Question 9

What is unilateral hearing loss?

Answer 9

• Unilateral hearing loss is one-sided hearing loss with the difference in hearing threshold level between the better and the poorer ear exceeding the average of 30 dB at 3000, 4000, and 6000 Hz.
• Unilateral hearing loss is not always a result of noise exposure; however, it is possible to have acoustic trauma in one ear (i.e., explosion).
• Other causes of unilateral hearing loss can be a result of viral, acoustic neuroma or other medical causes. For this reason, a worker needs to be referred for follow up.