In this work an experimental study on the effects
of the atmospheric attenuation on audio signals carried by a
laser beam in Free Space Laser Communication system. Both
of the attenuation factors, absorption &scattering has been
studied utilizing a frosted glass test cell for environment
simulation conditions. The results show an effective change
on the signals amplitude& pulse duration for different
locations of the test cell with respect to the receiver. Far-field
location produce defocusing effects while near field location
show focusing effects which reflects on the received signal
quality. Where an improvement of 200% has occurred due to
low divergence. Assuming constant noise effects in all of the
system, the experimental results show an effective reduction in
the S/N ratio and increase in the bit error rates.