It’s been centuries since Western music emerged from religious chant, and in that time an incredible array of instruments has evolved, from the bizarre and short-lived to the moving and canonical. And while we’ll likely retain the current variety of instruments, the close of the 20th century seems to have seen the end of the development of new ones.

There are, as I see it, three ways in which instruments evolve. First, there are instruments that evolve slowly over time, as instrument makers create slight, or drastic, alterations to a pre-existing structure in order to achieve a different function or improve the instrument’s sound. An example of this kind of instrument is the violin, which can be understood as a modification on the previously dominant family of string instruments, the viols. By making some structural alterations, the violin was born – a louder, more brilliant version of what came before.

Other new instruments crop up when instrumental structures, like that of the keyboard or the saxophone, are transformed into input devices for computers and synthesizers. Basically, these instruments translate the hand motions of the performer, who “speaks” saxophone or piano, into a synthesized sound – as in the case of any keyboard that looks and plays like a piano but makes no physical sound of its own. These instruments basically bridge the gap between performers and electronics and let them preserve their real-time technique while also altering the sounds they produce.

A third kind of innovation produced the electric guitar, where the hands retain their relationship with the original instrument but the sound is produced in a physically different way. While a traditional guitar resonates the air inside the instrument when a string is plucked, an electric guitar uses magnets to create an electric signal, which is turned into sound by an amplifier.

The first type of evolution is one that is clearly not under way in forms of contemporary music. The violin diverged from the viol family as music left the small chambers of the aristocracy to enter larger concert halls. This made the switch to a louder, more incisive sound necessary – the older viols could simply not soar over accompaniment like a violin. By now, however, we’ve seen ensembles as large as they’re likely to get, and much of the classical repertoire – at least, the pieces that tend to pack the concert hall – are written for established instruments.

The second type of evolution seems unlikely to be of real significance, since the piano keyboard is already the worldwide lingua franca of synthesizers. Whether or not it’s the most efficient way to translate pitches into a computer, it’s the best-known and most standardized way, and the tendency is more to learn the basics of a piano than to invest in some other format. Since pitches can be easily adjusted, there’s no need, even, to learn the piano in any traditional sense – one key will do.

And as for electrifying instruments, that trend seems to be complete. From violins to guitars, pickups have been developed, and anything else can simply be plugged into a microphone.

A possible exception to all of this can probably be found in percussion. While violins and guitars took hundreds of years to evolve, a percussion instrument – albeit a crude one – can be made in seconds. Evelyn Glennie’s experiments with exhaust pipes of different sizes, pitched to different notes and hit with a drumstick, exemplify the possibilities. Tan Dun’s “Paper Concerto,” premiered by the Los Angeles Philharmonic in 2003, does the same, featuring solos of sounds created by ripping, or otherwise manipulating, paper.

But while these can be termed new instruments, it’s doubtful that they will achieve a canonical place similar to that of a violin, trumpet or electric guitar. The invention of the instrument is linked to the composer in an almost compositional way, meaning that each successive writer may want to create their own instrument. They are also more limited than the classics; while two different concertos for ripped paper may come off differently, that will most likely be due to differences in the orchestra more than the solo part. The same goes for the new sounds – “instruments,” here, begins to lose meaning – that can be created electronically, either from scratch or by filtering recorded noises.

There’s not going to be a shortage of innovation any time soon, because the sonic options musicians are presented with are more abundant than they ever have been, from the “discovery” of instruments previously neglected by Western music to the use of electronics. But the fact is that innovation is going to come from new sounds, like paper in a certain piece or some noise in another, rather than from new instruments. The master instrument builder, hunched over the skeleton of a violin with tools and wood shavings, will be replaced by a similarly postured sound designer working with a palette of electronics.

If you’ve invented a new instrument that you are sure will catch on, e-mail LaRue at alarue@media.ucla.edu.