Cavities and active regions

A mobile electronic device, comprising:

• a case body;
• and
• at least one speaker unit or microphone unit in the case body;
• wherein
• each speaker unit or microphone unit comprises a housing defining at least one cavity region, a vibratable element in or proximate to the at least one cavity region and an active region that comprises an adsorbent element in the form of a self-supporting monolith-like element with a porous reticulated structure, wherein the adsorbent element includes an adsorbent material comprising a microporous organic polymer (MOP) material.

A microphone system, comprising:

• at least one transducer element for converting sound to an electrical signal;
• optionally a preamplifier that receives an output from the at least one transducer element;
• a housing or cabinet at a back region or side region of the transducer element;
• and
• an active region comprising an adsorbent element in the form of a self-supporting monolith-like element with a porous reticulated structure, wherein the adsorbent element comprises an adsorbent material comprising a microporous organic polymer (MOP) material.