INFRASONICON: Time-Compressing Infrasonic Recordings to Discover New Sounds, by Clark Huckaby

Examples of Sounds Recorded with Infrasonicon

Here are twelve time-compressed recordings that I made using the infrasonicon described in this web site (see Overview pages). If you find one or more that you want to use in a production of any kind, please feel free; I only ask that you let me know and that you properly credit the source of the sound(s) you use. I'd be very happy to post a link to your work here.

• Transducer: Optical Probe (measuring direct light emission)
• Description: This is a simply a flickering candle flame in a darkened room time compressed by a factor of 165. The "chirps" audible within the noise are brief episodes where the flickers are more periodic than chaotic. Figure 1 in the Overview shows this recording in progress and Overview Part 3 describes the optical probe.

• Transducer: Optical Probe (measuring transmitted light)
• Description: This is a half-hour recording of my pulse in the form of a time-compressed photoplethysmograph (PPG). With my left hand taped to a board for stability, I squeezed the tip of my index finger between a laser module and the TSL230 light-to-frequency converter chip using gentle pressure (see Overview Figure 7). A PPG measures volume changes, which are due to pressurized blood infusions with each pulse, as changes in optical absorbance. The original fundamental frequency was about 1.15 Hz or 70 heartbeats per minute. Time-compressed, why might this sound like a buzzing insect? First, wing flaps have a thrust stroke followed by a return stroke which could make a similar saw-tooth waveform (See Figure 8). Second, since insect wing flaps and human heartbeats are each regulated biologically, perhaps their frequencies could waver similarly (but on different time-scales).

• Transducer: Optical  Probe (measuring reflected light)
• Description: This and the following example are rotating objects that I spot-illuminated with a fixed laser pointer in an otherwise dark room. (See Overview Part 3 for a discussion of the optical pickup.) This example is a six-sided plumb bob wrapped with white tape and suspended by a string of rubber bands. After winding it up, I let the bob rotate back and forth on its axis. The first 65 seconds of this example represents three hours of recording into one wav file. I decided to record for another hour, so there is a 2-1/2 second gap corresponding to the seven minutes I took to make this decision and set up a second wav file. The complete example is an edit representing four hours and seven minutes of plumb bob activity, with a seven-minute gap in the recording, all played at 165-fold time compression.

• Transducer: Optical Probe (measuring reflected light)
• Description: For this track, I laser-illuminated the edge of a tarnished brass 6-inch flywheel (a gyroscope demonstrator with frame firmly clamped in a vise). I hand-accelerated the wheel to 270 RPM (calculated from the recorded waveform). The wheel coasted to a stall during about six minutes. A frequency analysis of this file appears in Overview Figure 6.

• Transducer: Water Theremin
• Description: On a calm mid-September day, I recorded water surface ripples on a lagoon in Eastwood Park, Dayton, Ohio (a photo of this session is in Overview Figure 10). The water was about 50 cm deep at the position of the transducer, and the maximum ripple heights were only about one centimeter crest-to-trough. At 266-fold time compression, the original 44 minute recording plays in just less than 10 seconds. This is "ambiance" only, because I didn't toss anything into the water and there were no boat wakes, nearby duck activity, etc. Even though it was a calm day, the lagoon's time-compressed surface waves sound something like raging wind. The mechanical background sound is wow and flutter from the audio cassette I used to record the frequency-modulated infrasonic signal in the field. The next example isolates this artifact.

• Transducer: None (un-modulated carrier only)
• Description: This file confirms that the "mechanical" background noise in Example 5 comes from cassette wow and flutter. I recorded 30 minutes of an un-modulated 1-KHz carrier (from my function generator) on a cassette then played it back through the data converter with the same settings as I used for Example 5. I now favor minidisks or other digital media for field recordings, which are free of audible wow and flutter.

• Transducer: Water Theremin
• Description: This is the resonance of water in a large sink. The water was 10-1/2 inches deep and its surface was 19 inches front-to-back by 22 inches side-to-side. The sink walls are vertical except for the front wall, which slopes forward at 25 degrees. The Water Theremin's antenna was six inches from the back wall and 9-3/4 inches from a side wall. Overview Figure 11 shows this set-up and Figure 12 shows the waveform resulting from one of the impulses. I made two separate impulses by gently immersing and immediately withdrawing my closed fist a few inches from the antenna. They sound similar to tom-tom strikes, but you can hear distortion that may be due to antenna-water adhesion (see comments in Overview Part 4).

• Transducer: Audio Amplitude Detector
• Description: Starting with this one, the rest of these example files are waveforms defined by the amplitude envelope of various audio signals (see Overview Part 5). In the present example, my old Yamaha RX21 drum machine played 10 different patterns or tempos for about 5 minutes each. The tempo for the first seven patterns is 100 quarter-note beats per minute (bpm) in 4/4 time (abbreviations: H = closed hi-hat, K = bass kick drum, S = snare drum): (1) solo H playing quarter notes; (2) solo K playing quarter notes; (3) like #2 but H added, playing eighth notes; (4) K on odd- and S on even-numbered beats, with H on off-beats; (5) like #4, except H plays on all beats plus swings the off-beats; (6) K plays a syncopated groove while S stays on even-numbered beats and H plays sixteenth notes; (7) same as #4. Staying on this last pattern, the tempo then changes to (8) 150 bpm, (9) 200 bpm, and finally (10) 250 bpm. As expected, the pitch of the time-compressed envelope depends on tempo while the timbre (harmonic content) depends on composition. The drum machine waveform pictured in Figure 14 represents pattern/tempo condition #9 of this file.

• Transducer: Audio Amplitude Detector
• Description: Unlike the strict periodicity of a drum machine's output envelope (Example 8), the audio amplitude of human speech is irregular and mostly arrhythmic. The expected result is noise, as this time-compressed envelope from an hour of "talk radio" confirms. The radio was tuned to a syndicated politically-oriented "talk" show. I could be facetious and say this orientation might only add to the noise. More seriously, perhaps poetry read with great precision would yield less noise. The speech envelope waveform in Figure 14 came from this wav file.

• Transducer: Audio Amplitude Detector (stereo channels summed to mono)
• Source Audio CD: "Dark Side of the Moon" by Pink Floyd (1992 digital remaster of 1973 recording) Capitol CDP077774600125
• Description: When the amplitude envelope of music is time-compressed, the strongest rhythmic components should contribute to tone, while vocals, solos, and fills (etc.) should tend to add noise. This example along with the following two are amplitude envelopes of entire audio CDs, which seem to confirm this. On "Dark Side of the Moon," notice how the heartbeat effect (fading in at the beginning and out at the end) makes tones similar to Example 2 (but much shorter). In between, the dynamics of songs determine how loud the time-compressed envelope sounds.

• Transducer: Audio Amplitude Detector (stereo channels summed to mono)
• Source Audio CD: "BR5-49" by BR5-49 (1996) Arista-Nashville 07822-18818-2
• Description: BR5-49's eleven country songs clearly have different pitches and timbres after they are reduced to their amplitude envelopes and then played at 165 seconds per second. The 10th song is a four-minute ballad (Bob Buchanan and Graham Parson's "Hickory Wind") with vocals well on top of the mix; notice how it translates mostly as noise, in contrast to the other (more beat-heavily dance-worthy) tracks.

• Transducer: Audio Amplitude Detector (stereo channels summed to mono)
• Source Audio CD: "MDMA Volume II" by DJ Skribble and Anthony Acid (1999) Warlock Records WR-2811-2
• Description: With its strong, relentless beat, maybe the time-compressed envelope of dance club music is less noisy than that of rock or country. This example lends some support to that idea. Since this is a dance mix (MDMA stands for "music 4 dance music 4 attitude"), its tempo is uniform through most of the 74 minute/16-track CD--except where Skribble & Acid gradually slow it down during track 8 ("Feel the Drugs;" audible here as a decreasing pitch sweep). But notice how the harmonic content (timbre) of the time-compressed envelope changes when grooves change between different tracks and sections.

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