Sound and hearing
Sound : The
sound is a mechanical vibration ( an oscillation ) transmit by the air to our
ears ( or a microphone ) . The frequency
of this oscillation is
expressed by the unit Hertz ( Hz ) that means an
oscillation by second . The human ear can understand frequencies between 20 Hz and 20.000
Hz .
Speed : The sound move at a speed of 340 meters by second in the air , what explains
the phenomenon of echo and that we see a lightning of storm before to hear it .
The LA : The
frequency of note LA , that serves as reference to tune musical instruments
, is 440 Hz . This is also the telephone’s tonality ( in
The ear: Sounds have a scale of sounding pressure very
great . Thereby
the ear has a conversely proportional reply per sound volume
.
The ear does not
understand bass and trebles on the same manner according to the volume of the sound . More the
sound is strong more the basses and trebles are heared .
Basses : Bass sounds are channeled by walls ( ground,
ceiling ) that increases their relative level ( x2 to x4 ) . The worse places are the corners of rooms .
It is necessary to
think at preceding remarks , if we want to make an
opinion concerning a sound reproduction , and to listen at a volume equal to
the reality .
Trebles :
Mediums sounds and trebles are rather directives . They have the feature to be reflected by
walls ( reverberation, echo ) .
The ear: The age of a person ,
or the fact that it has been submitted to high sound pressures , decreases the
perception of the sound ( mainly of
treble sounds ) .
Tinnitus : A
person that has been submitted a long time to heavy sounds has also ears that
whistle all the day .
Silence : The
perfect silence does not exist . There
is always a little noise . In all manner in a total silence we can hear
the noise of the blood circulating in ears .
