For this listening journal, I looked at Numerology (1960) – Max Mathews
According to the descriptions, this piece was produced to demonstrate the possible sound effects achieved with computers in the early 60s. It is structured in eight sections, each dedicated into a single matter, exploring timbre problems (musicainformatica.org).
As we can hear, the opening of this piece directly dives into a constantly rising humane-like siren sound, which might be indicating the pitch shift technique. Afterwards comes a syncopated two-part melody in legato, in a rather thin timbre. The next section repeats the same melody, but in a more staccato way, and maybe less bit-depth. The following section is applying pitch-shift to each of the notes played in the melody, which sounds similar to keep using the scroll button on a midi keyboard while playing the music. After this, the piece developed into a variation, combining pitch shift, flanging (maybe?), high and low filters, EQ and other effects. We can hear the piece tuned into a more percussive or melodic format, or some video-game-ish sound effects.
After all, the piece corresponds to its title by stimulating a mysterious yet unveiling feeling with computer-based sound techniques.