What makes a note?
The words ‘tone’ and ‘note’ refiect the subjective/objective nature of sound: a tone is a sound wave with a particular frequency, a note is its subjective impact, with a particular pitch.
In addition to pitch, a note also has duration, loudness, and timbre. Timbre is by far the most important in identifying instruments by their sound, and is also the main carrier of emotional content. It is actually an uneasy bedfellow with the others, being far more complicated. It is a bit like deffning a person by gender, height, weight, and ffngerprint: the ffrst three parameters can each be speciffed in terms of one value of a single unit, but the full description of an individual’s ffngerprint would be highly complicated and multidimensional. But, like a ffngerprint, timbre is the only thing unique to a particular instrument or person, so it’s the only thing that the brain can use as an identiffer.
A problem for the brain which the ffngerprint detective need not worry about is that timbre is a dynamic quality; it changes over time. The timbres of a cymbal, piano note, or drum all change radically from start to ffnish (this change is known as fiux). The timbre of a particular instrument or speaker also changes with pitch and loudness: a cello’s high notes have a diflerent quality to its low ones, a shouted word is not simply louder than a spoken one, and a man’s voice at the top of his range sounds much thinner than when he is singing low notes. Fortunately, we can rely on our highly evolved ability to focus on the very ffrst sounds made by a source to untangle all this.
Prehistoric agendas
Our modern appreciation of music and our dislike of noise probably stem from the evolutionary pressures that moulded the hearing systems of our distant ancestors. Their ffrst priority on hearing a sound would have been to identify it, and there was no time to ponder. The twang of a bowstring, the rumble of an avalanche, the thunder of approaching hooves or the warning hiss of a snake are only of benefft to the hearer if (s)he can react fast, and so the hearing system concentrates its analytical prowess on the earliest moments of a sound. This has the surprising consequence that the ‘attack’ sounds that an instrument makes in the ffrst fraction of a second, though generally discordant and nothing like the instrument’s ‘steady state’ sounds, are the ones that enable us to identify what that instrument is. A recorded piece of music edited to remove all the attacks sounds very strange, and the instruments could be anything. This fact stymied for many years attempts to synthesize instruments convincingly.Often not just the instrument but the composition too can be identiffed within the ffrst second. There was once a fairly popular radio (and then TV) quiz show called Name that Tune, in which contestants frequently succeeded in identifying tunes from just four or even three notes. It is very easy to outdo this if one is presented with a familiar recording: even a preliminary fumble or intake of breath is enough to identify it. Conversely, some musical sounds immediately inform the listener of the fiavour of the whole piece: a single chord may have a ‘Mexican’ sound, a few violin strokes might sound ‘folksy’, a bagpipe skirl ‘Scots’, or a couple of notes ‘fferce shark approaching’.