Conventional cord-bound telephone apparatuses are generally equipped with dynamic
hearing capsules. These hearing capsules are characterized by very good acoustic
Due to the internal
structure, these transducers produce strong magnetic fields within the low-frequency range
from some hundred Nanotesla to some thousand Nanotesla and are definitely not
radiation-free thereby as is unfortunately often falsely stated.
How does a piezo-acoustic principle function ?
A ceramic material of certain composition is poured in 0.1 mm thick foils. As from a
"Cookie dough" disks are punched and burned. Both surfaces of the discs are
metallized, and then polarized contacted and glued on a membrane.
Piezo crystals have the characteristic to release in the compressing current, for example
Piezo lighter. Be the metallized areas with power provided the crystals pull together.
The membrane glued to the piezo crystals have a self-resonant frequency. If it is
generated with one of the geometry of the disks and diaphragms of certain frequency, is to
be heard a pure tone, for example ringing. Through acoustic elements, resonators, back
room volume etc., the self-frequency of the diaphragm can be attenuated and the remaining
frequencies reinforced. For use in telephones the required curves are reached by the
design of the housing. The piezo technology requires significantly higher manufacturing
precision than the manufacture of a dynamic capsule.
Own and other measurements with a modified piezo phone show that it is possible to produce
a nearly magnetic field free Piezo phone. The load of this Piezo phone handset by
low-frequency magnetic fields as well as by static magnetic fields (permanent magnets) is
very strongly reduced. Compared to the average capsule (dynamic hearing capsule), the
magnetic fields due to the piezo technology are reduced to approximately 99%.
||Important notes about phone
calls with piezo technology:
The used piezo hearing capsule emits no electromagnetic fields, therefore a coupling with
a hearing aid is not given over the electromagnetic switching network.
In extreme hardness of hearing, the phone is not recommended. With small and middle
hardness of hearing when using the telephone no disadvantage was determined. In the doubt
hearing aid carriers should test the telephone before the purchase.
Since the piezo hearing capsule from the physical impact is reversible, hearing capsule
function also as microphones and in vice versa. Experiments have shown that the powerful
hook of the telephone handset can generate high tensions in the phone.
An appropriate treatment of the phone avoids functional
errors and extends the life span. Electronic preventive measures are intended, which are
to prevent high tensions, yet can extreme mechanical effects lead to malfunctions.
Piezo phones are among other things available at the following company:
Keywords: electrosmog, piezotechnology,
magnetic, cablebound phone