Almost no difference between this doorbell sound and the original. Of the four
doorbell sounds three are unique in tonal changes.

These samples were made from tones originally less
longer than 20 seconds. The single-pitch sine
waves were shortened and lengthened by changing
tempo and changing the speed. Changing the speed
with the Audacity affects both tempo and speed.
In evolving the wave to the doorbell sound(which
unfortunately has some high-pitched distortion),
I subjected segments of the wave to equalization
and amplification, then using other filters to
modify the sound more. Included were a Bode frequency shifter, a phaser plug-in, and some
more plug-ins or filters.

Comments