Siemens MUSIC Pro - Manual (Page 44)

So-called zinc-air batteries are
used today almost exclusively
in hearing instruments to
minimize environmental
damage. These batteries
require oxygen for operation,
which they absorb from the
air. The battery is activated as
soon as the protective foil is pulled off and is used up even
if you do not use your hearing instrument.
You should always pull off the protective foil only if you
actually use the battery. Also, do not leave the batteries in
your hearing instruments if you do not use them over a
longer period of time. The batteries can leak and damage
the instruments.
Zinc-air batteries which are almost completely used up show
the following behaviour: After switching on the instruments
they function completely normally, but then rapidly become
quieter. The more the battery is used up, the faster the gain
falls off. You must then replace such batteries by new ones.
Handling batteries
44