expandable material

Hello everyone,

I’m kinda new, but when I found this board I immediately registered, so many cool topics!

I’m currently working on expandable hearing protection. Why? Current hearing protection, those made to measure ear plugs especially seal off the ear canal entirely. This creates an uncomfortable feeling because there is pressure in the ear canal. I want to develop ear plugs that can expand when higher loudness volumes are reached. So there will be only pressure when needed for sound damping. This expansion can be trhough filling the plug with air or water with an actuator.

At lower loudness volumes the ear plug is in deflated state, but remains more comfortably in the ear. When higher loudness volumes are reached the earplug expands gradually as the volume increases.

Does anyone know a material that can expand throug the use of air / water and is still comfortably to wear? (currently acrylic and silicone is used). The expansion only has to be 1 or 2 mm, so a possible increase of 10 / 15 percent is enough.

Kind regards.