By Marley Sullivan
Published: December 29, 2022.
One of my passions as a sound artist is to show you new ways to hear a sound. One strategy I love is to amplify it not in volume but in time, stretching & altering it to unearth microscopic textures and details hidden within.
For example, this recording of myself making a wine glass "sing" hides an otherworldly orchestra & choir!
In this example, I slowed the playback speed, lowered the pitch, and used the Paulstretch algorithm to stretch it.
Then I used a bit of sound physics knowledge for the next part. Every sound you hear is made of many pure sine waves mixed together, and the combination of their frequencies is what gives the sound the timbre (texture) you hear. The lowest frequency is called the fundamental, and it's what your brain registers as the pitch or musical note of the sound. All other frequencies above the fundamental are called overtones, and they are registered in your brain mostly as timbre rather than pitch.
So, at this point in working with the sound, the fundamental frequency was a low bass note that overpowered all other texture in the sound. I used a spectrum plotter to determine the frequency of the fundamental, and confirm there were plenty of overtones above it.
Next, I applied a high-pass filter to remove the fundamental, revealing textures from overtones that were previously too quiet to hear. Also note that earlier I slowed the playback speed and lowered the overall pitch of the whole recording, so these textures were originally very high pitched.
When I heard the end result, I was blown away! I didn't expect to get the sound I did just by editing the recording. Now I try similar processing techniques on other sounds I find to see what other new, hidden sounds I can uncover.