In both fields the amount of gain is measured in decibels at or just below the point at which the sound from the speaker driver re-enters the microphone and the system begins to ring or feed back.
If the performer reduces the distance to the microphone by half, the PAG is increased by 6 dB while the environmental sounds remain relatively the same.
[6] A small amount of pitch shift applied to the signal can increase GBF, as can the addition of a few milliseconds of straight delay.
The shape of the earmold is a factor, with larger and heavier designs capable of delivering greater GBF.
To prevent feedback with the highest amounts of gain, such designs require the tightest-fitting earmolds with no venting, and the deepest penetration of the ear canal to place the speaker driver as close as practical to the eardrum.