Document ID: chunk:federal_register_of_legislation:F2023C00151:reg:4000:p2
Version: federal_register_of_legislation:F2023C00151
Segment Type: reg
Provision Reference: reg 4000 (pt 2/8)
Character Range: 274764–277435

Threshold of Reliability.

Bone conduction HTLs in excess of 60 deciBels are generally unreliable. At the 500 Hz frequency, bone conduction HTLs in excess of 45 deciBels are unreliable.

Thus a set of thresholds of reliability for bone HTLs is defined as follows:
for    500 Hz 45 deciBels
for  1000 Hz 60 deciBels
for  1500 Hz 60 deciBels
for  2000 Hz 60 deciBels
for  3000 Hz 60 deciBels
for  4000 Hz 60 deciBels

Figures in excess of the threshold of reliability for bone conduction are not used in calculating the impairment due to hearing loss.

For sensorineural hearing loss, whenever the bone conduction HTL exceeds the threshold of reliability, the air conduction HTL for that frequency and side is to be used instead of the bone conduction HTL.

For conductive hearing loss, whenever the bone conduction HTL exceeds the threshold of reliability, the threshold figure for that frequency and side is to be used instead of the bone conduction HTL.

The above arrangement gives to the veteran the benefit of any doubt relating to the intrinsic unreliability of bone HTLs.

           Substep 3A: Calculation of accepted hearing loss for types 7, 12, and 15.

Substep 3A applies to these types of accepted hearing loss:
 Type 7 Bilateral Conductive deafness
 Type 12 Right Conductive deafness
 Type 15 Left Conductive deafness.

For each type, one of two methods is to be used:

Method 1 is to be applied if both air and bone conduction HTLs are available. In this case both the air and bone conduction HTLs are calculated and a formula is applied. In calculating the bone conduction HTL, if the bone conduction HTL exceeds the threshold of reliability, the threshold figure for that frequency and side is to be used instead of the bone conduction HTL.

The terms "air conduction PLH (Percentage Loss of Hearing)" and "bone conduction PLH" are used in the formulas. These are calculated in a way similar to that in which APHL is calculated for other types of deafness.

Method 2 is to be applied if only air conduction HTLs are available and if it is not practicable or appropriate to obtain bone conduction HTL values as a result of any of the reasons described on page 108.

Type 7. Bilateral conductive deafness

Method 1 (to be applied if both air and bone conduction HTLs are available):

First:
Air Conduction PLH is to be calculated using right and left air conduction HTL values, and

Bone Conduction PLH is to be calculated using right and left bone conduction HTL values.

Next:
Using the air conduction and bone conduction PLHs, the PLH for bilateral conductive deafness is calculated by applying the following formula:

(where "A" is