These earplugs have a small electroncially controlled diaphragm aperature that can open and close based on how much ambient noise there is. So when there is very little noise, the earplugs don't block much. But as the noise level approaches more and more dangerous levels, the earplug blocks more and more sound. This would be good for rock concerts or construction so you don't have to keep taking the earplugs in/out to have a conversation during the more quite moments. These would have an internal rechargable lithium ion battery and we be recharged periodically via an inductance recharger.-- DeathNinja, Jul 17 2003 Sound cancellation headphones/earplugs http://reviews.cnet...7728.html?tag=glnavA baked solution? [dweeb, Oct 04 2004, last modified Oct 05 2004] The net effect is the same, so why bother?-- phoenix, Jul 18 2003 Sound cancellation headphones/earplugs adapt to the amplitude of the noise to provide a consistent low noise level at the ear. Futhermore, if there is music or speech that one desires to hear, a music device or microphone can be plugged in to bypass the cancellation.
It sounds like you may be arguing for a volume control where the aggressiveness of the blocking/cancellation can be adjusted. Since blocking/cancelling sound inevitably reshapes the spectrum, It is much more desireable to eliminate the sound as much as possible and then add the desired sound (e.g., concert) through a balanced amplifier as is done with the cancellation systems.-- dweeb, Jul 18 2003 My brother has some like this for shooting. The microphones are situated on the outside of the earpieces and can be turned up or down, on or off so that you can hear the conversations around you. When the gun is fired the microphones shut off.
Any sound over a certain decibel range causes the microphone to shut off for a split second. Probably not good for concerts, but could provide a basis for implementation.-- vendetta, Jul 18 2003 This is called "peak clipping" and it's comprehensively Baked, I'm afraid - in hearing aids, ear defenders, and active earplugs.-- 8th of 7, Jul 18 2003 random, halfbakery