An earpiece auditory device is described which includes a behind-the-ear component shaped to fit behind the ear of a user. At least one piezoelectric measuring element being positioned between a diaphragm placed on the pressure side of the inner housing and a base part of said inner housing. A type of activity the user is currently engaged in is inferred from the received user activity metrics. , metals, glass materials and ceramics, free from emission of any organic matters. The invention also provides methods for the treatment of diseases caused or affected by malfunction of the immune system.