We have the first "flat frequency response" earplug as measured using the data attained by the Virginia Tech Auditory Systems Laboratory. We are not the first "flat attenuation" earplug. Here is the difference:
Earasers utilize “V-Filter”™ Acoustic Resonance Technology which essentially inverts the natural resonance of your ear canal. While the resonance of the ear does a fine job at amplifying soft sounds, it is the main reason loud sounds become unbearable. The natural ear canal will add 17-20 decibels of sound pressure at 2700Hz which you simply don’t need in a loud environment such as listening to a live concert. (see our graph on the specification page). By inverting the natural resonance of the ear canal, we achieve the only flat frequency response earplug on the planet! (+- 4.5dB; 125Hz – 8000Hz). While other brands offer a “flat attenuator” they are still causing a peak resonance (same as your natural ear) in the most likely region for hearing loss (high frequency hearing loss). This is also the most sensitive region for hearing and creates discomfort in loud environments.
There is a big difference between “Flat attenuation” and a “Flat frequency response!” So, what you might be seeing in their advertisements is confusing and possibly misleading. If they declare "response" then it should be measured at the eardrum, and that would include the ear canal resonance. "Flat frequency attenuators" try to bring everything down equally, but that is not typically well received by musicians, regardless of the good intentions. After all, the ear is not linear. Starting from a regular volume, if you increase the amplification, it becomes necessary to change the equalizer to achieve "normalcy" (research "loudness growth contours"), so why would you keep the equalizer "flat" when you lower the volume?