SOUND facts and definitions

Typical gas well drilling activities increase the ambient sound levels 20 to 25 dB(A) at 200 feet from the drilling rig. After 90 days of field sound level testing in Fort Worth, data has shown that installing sound control systems can result in the following sound level reductions.

Drawworks Brake Shroud

• 10 to 17 dB(A) reduction at 10 feet
• Inaudible at 300 feet

Sound Blankets on the Rig Floor

• 8 to 10 dB(A) reduction at 300 feet

Sound Blanket Wall

• 18 to 22 dB(A) reduction at 120 feet

The pre-drilling ambient level is the background sound level one hears at the site before any drilling operations begin.

A decibel, or dB, is the unit to reference the sound pressure level.

A reduction of 10 dB(A) at any level will reduce the level of loudness one hears by 50%.

The human ear cannot detect a change in sound until there is a 3 dB(A) difference.