explanantia

"...detectable transients": Admittedly I am using the term "transient" in an unconventional, slightly novel way, and I think this warrants an explanation. In the audio or electroacoustic realm, a transient typically refers either to the initial upswing of a waveform or a brief burst of noise found at the very start of the attack portion of a sound. For example, a ride cymbal being played with a stick produces a sharp initial pulse or "click" which is actually a spectrum or mixture of extremely high frequencies with a steep, yet non-zero, amplitude decay; that is, the transient dies away quickly and gives way to a progressively more muted-sounding spectrum produced by the fundamental frequency of the cymbal and its characteristic overtone series. The latter is responsible for the extended "crash" or "ride" sound that dies away much more gradually over many seconds as the energy of the vibrating cymbal slowly dissipates into the surrounding air.

Here, however, I am using "transient" to refer to each individual "up" cycle of a waveform, no matter where they occur. Technically, this is wrong. Why am I doing this? Well, the reason is this: if you make a two-dimensional plot of some audio-frequency waveform, that waveform has to have a beginning somewhere. Where is that beginning? Essentially it's arbitrary. It can be anywhere you like! It wouldn't have to be the "up" cycle. It just as easily could be the "down" cycle": the point is that there is some cue our brains latch onto, by way of neural entrainment, that enables a signal to be "correctly" interpreted as belonging to various species of rhythm and pitch. Sounds are vibrations in air or water no matter when or on what time scale they occur. That is to say, a transient is something of a formal designation referring to a specific feature of a sound or its oscillogram. But the phenomenon of sound itself is continuous. Here on Earth, the world is never silent. At every moment, some combination of tones prevails at any location, including those outside the range of human hearing. A transient, then, in this sense, is some detectable change that either initiates OR sustains an audible phenomenon.

 

Sorry for the confusion.