Millions of people walk every day with a strong beat in the ear of smart
phone or MP3 player through the day. Most of the crowd, so that they are
risking hearing damage. Systems for automatic volume control are still
few friends: Their sound is too bad. The U.S. firm dB Logic from
Indianapolis, has therefore developed a set of headphones, the maximum
volume automatically limited, yet will not spoil the listening
experience with intense, noisy places, reported Technology Review in
its online edition. Even quieter passages remain audible.
According to a study commissioned by the European Commission extend the
maximum possible volume of portable music players 88-113 decibels, while
the headphones can still sometimes get out a few extra decibels. For
comparison, it takes on a normal conversation 60 decibels. 120 decibels
is the noise of an airplane taking off when you're standing nearby. The
EU study estimates that currently risk up to 10 million listeners in
Europe, serious permanent hearing damage.
The new headphones from dB Logic now controls a circuit, the maximum
volume. Stream are fed to the audio signal so that its own batteries are
unnecessary. Heart of the system is a tiny transformer. He sets the
voltage from the audio signal up to a value with which the transistors
of the volume control can be controlled. The volume is not simply cut
off at a maximum value, but adjusted to an average of 85 decibels. Short
louder passages remain untouched.
Other previously used methods can not. One example, using a weakened
opposition, the audio signal continuously, independent of current from
the volume. Cut at a different diodes all audio signals at a certain
decibel threshold from. The Durchschnittstlautstärke of 85 decibels had
been chosen because the U.S. prescriptive authority for safety from this
value at work by wearing earmuffs, says Med Dwyer, co-founder and CEO of
Logic dB. "Few people will perceive this as a level not loud enough,
especially not our target group of younger people," said Dwyer.
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