Amplitude and frequency attenuation vs. distance

["Jim Morgan" fundador_four]

As most of us know sound amplitude and frequency are attenuated as the
distance to the sound source increases.


This effect heard from recordings made of various sounds at different
distances are often noticeable but difficult to clearly hear.


Also recordings made with parabolas amplify the higher frequencies more than
the low frequencies thereby making the recorded sound seem closer than it
actually is.


The following test of sound vs. distance is an example of sound amplitude
and frequency attenuation.


Here is a description of the test which is the recorded sound of a kitchen
timer bell at 15, 30, 60, 90, 150, 300 feet.  Note the significant
attenuation of the higher frequencies that increase with distance.


Recording at: http://soundcloud.com/fundador/bell-test-15-30-60-90-150-300


Recorded with a 23 inch Telinga Twin science parabolic microphone in an open
field with no obstructions between the bell and microphone.


Best regards,


Jim Morgan

Prescott, AZ USA