If that is all they did I'd be happy but if you have ever worn earplugs you know how annoying it is to always pull them out to hear normal conversations or how foolish it is to start shouting while wearing them. The MPs provide a way to have natural hearing until the sound exceeds safe levels. Called wide-dynamic-range adaptive compression, their operation is automatic with nothing for the wearer to do but insert them in their ears and enjoy the concert!

Each of the MP-9-15 earplugs uses a balanced armature driver (miniature speaker similar to in-ear monitors), a sensitive microphone, and Etymotic's proprietary K•AMP® signal processing to automatically and quickly change the sound level delivered to your ear canal based upon both the average and peak loudness of all external sound.

Each earplug has a swing out battery compartment door/switch that turns on and powers the electronics using a single, 1.45-volt (312) hearing aid battery--once the tab on a fresh battery has been removed and under normal operation, battery life is at least two weeks continuous operation.

Next to the battery door on each earplug is a mode select switch for the two modes of operation called 9dB and 15dB--so named to indicate the amount of SPL reduction.

In the 15dB mode, the MP's pass sound like an open ear and when the sound level crosses the 70dB SPL threshold they begin a gradual reduction of the sound delivered to your ear until the external SPL reached 100dB. Above 100dB SPL continuous sound, including any loud and sudden impact noises such as cymbal crashes that occur at any time, are immediately limited and reduced by a constant 35dB SPL. The 9dB mode boost all sound up to 85dB SPL but, starting at 70dB, the dynamic attenuation curve and overall operation is the same except 9dB less reduction overall.

I received a pair for review and immediately like that they do not require custom ear molds as other custom earplugs. They come with a complete assortment of reusable foam, Glider, and three-flange ear tips, a cleaning kit, extra batteries and complete instructions.

I played a record I mixed recently, turned on my SPL measuring meter, cranked up my stereo until the meter was reading between 90 and 102dB SPL on peaks.

With MPs properly inserted and set to the 15dB position, it was amazing! In my listening position equidistant between my stereo monitors it sounded great--full stereo with good stereo imaging and frequency balance. Removing the MPs checked reality for me--my speakers were throbbing loud! With the MP-9-15s inserted, it was just a loud playback.

Amazing to me is this: when I stopped playback I could hear the traffic noise from the street "fade up" into my ears. If this were people talking, I would have been able to converse in a normal voice instead of shouting. In the 9dB mode, all is the same except everything is louder and that position might be better for musicians or older people with a threshold shift in their hearing.

I like the super fast attack time characteristic and slower release time of the dynamic adaptive attenuator processor--a pleasant curve to hear people talking around you when the music stops at the concert. I found them perfect for all sorts of activities as well: using loud power tools, attending car races or sporting events.

Now part of my studio kit, I use them in the recording studio to adjust/change microphones around loud drum kits or guitar amps while the musicians continue to play. I love them because when I go back in the control room to check the results of changes, my ears are not ringing from the high SPL in the studio compared to the quieter monitor speakers.