 Among various new ideas , Grainger introduced his so @-@ called " free @-@ music " theories . He believed that conformity with the traditional rules of set scales , rhythms and harmonic procedures amounted to " absurd goose @-@ stepping " , from which music should be set free . He demonstrated two experimental compositions of free music , performed initially by a string quartet and later by the use of electronic theremins . He believed that ideally , free music required non @-@ human performance , and spent much of his later life developing machines to fulfil this vision . 
