Here is a CD containing a recording of air pressure fluctuations. When played on ordinary audio equipment, the recorded air pressure fluctuations (technically named infrasound) are reproduced at 360 times the original speed, and thus can be perceived by our ears as sounds.Here is a CD containing a recording of air pressure fluctuations. When played on ordinary audio equipment, the recorded air pressure fluctuations (technically named infrasound) are reproduced at 360 times the original speed, and thus can be perceived by our ears as sounds.Here is a CD containing a recording of air pressure fluctuations. When played on ordinary audio equipment, the recorded air pressure fluctuations (technically named infrasound) are reproduced at 360 times the original speed, and thus can be perceived by our ears as sounds.