Music, CompuMaestro -- like Radiohead, please...

USC engineer/musicians create style-specific computer musical accompaniment-songwriting system

This is a schematic. Click here for more information.

It's an archetypal exchange in musical performance. A vocalist stands poised to perform. The guitarist alongside is ready to add depth and harmony to the melody.

The guitarist doesn't know the song but "hum a few bars and I'll fake it," she tells the singer. "Could you do it in the style of Radiohead?" asks the vocalist. "No problem," the versatile guitar player says.

Now a software system created by two University of Southern California researchers can do the same -- not just create an appropriate accompaniment, but do so in the style of any chosen artist, or even the particular style used in select pieces by the artist. The system can potentially run on an ordinary PC.

Elaine Chew, an accomplished pianist who is a professor at the USC Viterbi School Department of Industrial and Systems Engineering, and graduate student Ching-Hua Chuan began working on their ASSA (Automatic Style Specific Accompaniment) system two years ago.

Chuan is a guitarist who has played with a number of rock bands in her native Taiwan; she received a PhD in computer science from the Viterbi School in 2008. Her prizewinning dissertation presented much of the ASSA research.

The aim, according to a paper presented a year ago at the International Joint Workshop on Computational Creativity in London, was as straightforward as it is ambitious: "... we describe an automatic style specific accompaniment system that makes songwriting accessible to both experts and novices. ... [T]he system should be able to identify the features important to the style specified by the user, [enabling the user to] ask for harmonization similar to some particular songs."

The ASSA system meets the challenge, according to both subjective and rigorous statistical tests.

In the London presentation, titled "A Hybrid System for Automatic Generation of Style-Specific Accompaniment," Chuan and Chew laid out the basics of the system, and tested it on Radiohead songs. They trained the system on three Radiohead songs, and generated chord progressions for the fourth; the original (i.e. Radiohead's own) accompaniment served as "ground truth" — that is, the test for the aptness of the accompaniment.