Editing Earplug (section)

===Electronic earplugs===
The noise reduction of passive earplugs varies with frequency but is largely independent of level (soft noises are reduced as much as loud noises). As a result, while loud noises are reduced in level, protecting hearing, it can be difficult to hear low level noises. Active electronic earplugs exist, where loud noises are reduced more than soft noises, and soft sounds may even be amplified, providing [[dynamic range compression]]. This is done by having a standard passive earplug, together with a microphone/speaker pair (microphone on outside, speaker on inside; formally a pair of [[transducer]]s), so sound can be transmitted without being attenuated by the earplug. When external sounds exceed an established threshold (typically 82 dBA SPL), the amplification of the electronic circuit is reduced.  At very high levels, the amplification is turned off automatically and you receive the full attenuation of the earplug just as if it were turned off and seated in the ear canal.  This protects hearing, but allows one to hear normally when sounds are in safe ranges – for example, have a normal conversation in a low-noise situation, but be protected from sudden loud noises, for example at a construction site or a while hunting.