Lysogeny for harp and computer-generated sound (1983)

The other interesting composition was Carla Scaletti’s Lysogeny, named after the way viruses wreak havoc on DNA strands in cells. The work itself, for harp and tape, played by Allysa Hess, was surprisingly refined and intriguing, its strands repeated and dissected, accompanied by cascades, and knockings and pauses. — Edward Rothstein, New York Times



Score for Lysogeny (Printed using the Interactive Music System on CERL PLATO)

A video of the last section of Lysogeny with the composer playing harp:

Program note

A lysogenic virus injects its DNA into a bacterial cell where, unlike other viruses, it does not immediately replicate and lyse the cell. Instead, when the cell’s circular DNA breaks apart in preparation for replication, the viral DNA attaches to the cell’s DNA. The cell then replicates both its own and the viral DNA. In this way, the cell may acquire some characteristics of the virus. Later, the virus may re-enter the lytic phase and replicate itself inside the cell, lysing the cell and scattering new copies of itself to infect other cells. During this process, at the moment the viral DNA breaks apart from the bacteria’s DNA, it sometimes takes a piece of cellular DNA along with it before going on to infect other cells. Characteristics of a cell may, in this way, be transferred to other cells by way of the virus.
It seems that we pass ideas around, from mind to mind, in a similar fashion. A new idea attaches itself to your mental DNA, changing the way you think. Later, when you pass this idea along, it’s been subtly changed — altered by your own experience and ideas. In this way, ideas spread through the population not just as isolated memes but carrying along bits and pieces of information, ideas, and experience from each mind they ‘infect’ along the way.
This piece is dedicated to my father, who taught me about lysogeny.

Composition notes

The piece was composed by taking the original sequence, joining its endpoints in a circle (like the bacterial DNA), picking random split points, injecting a linear sequence (the viral DNA) and during the development, ripping random-length sub-sequences out of the longer sequence and re-injecting them into new circularized patterns.
A second pass (written in FORTRAN) was then made over the score to automatically identify tuplets, short phrases, long phrases, and the highest pitch within each phrase; within each phrase, small adjustments were made to the durations and amplitudes to make the phrases more identifiable to the listener and making the computer-generated part sound more “expressive” and lively.

Technical notes

Realized on the University of Illinois IBM 4341 using Barry Vercoe’s MUSIC 360 and converted at the University of Illinois Speech and Hearing Sciences psychoacoustics lab. Score printed at Computer-based Education Research Lab (CERL) Sound Group using Lippold Haken’s LIME software.