Too much muffling can cause a feeling of being isolated, because this blocks most tones. It can even cause disorientation, dizziness and/or nausea. Completely sealing off the earplug can also cause you to become tired much more quickly.
In certain cases you want to be well protected against excessive harmful noise, without too many other sounds being blocked. For this, we have developed filters which muffle certain tones and not others. Thus you can ride a motorbike without damaging your hearing, for example, but you can still hear other traffic, your motorbike, a siren and horns beeping. You can go to a concert safely, without compromising on the quality of music and the intelligibility when others speak.