Designing Sound is the title of a research and development project, and also of resulting computer music software and curriculum materials. Too often the production of computer software has been driven by commercial pressures, not educational needs. A five year project ran from 1987 involving a number of schools in England in a program of action research. A computer program to support creativity in music education with children from 4 - 19 years of age was developed and published from this project. The software enables all children to become involved in composing as a curriculum activity, whatever their musical ability. Supporting materials provide guidelines for classroom applications and include approaches to the assessment of creative work.Criteria for evaluating educational software in curriculum music are proposed, and the program has been written in versions which will run on a range of computers. Designing Sound represents a concept in the use of new technology in music. Future developments may enable this philosophy to be incorporated into multimedia computer platforms.