Systems for the reproduction of music are limited in the frequency range and in the amplitude of the sounds which they can reproduce without distortion. In order to determine what requirements such a system should meet for faithful reproduction of common forms of music, those instruments which were believed to contribute largely to low or high frequencies, or to have large amplitudes at any frequency, have been investigated. Those examined were: bass drums of three sizes, snare drum, cymbals, triangle, bass viol, bass saxophone, bass tuba, trombone, trumpet, French horn, clarinet, flute, piccolo, piano, and organ. Several measurements have also been made upon complete orchestras.The measurements included average and peak sound pressures corresponding to the whole spectrum, and also the same quantities in thirteen bands of frequencies which together covered the complete spectrum. Several hundred peak measurements were taken in each band, each measurement representing the highest peak in one‐eighth second of music. They were taken in such a way that the frequency of occurrence of the peaks in ten amplitude zones, each zone covering six decibels, was obtained. The musician in each case played a representative selection for his instrument, lasting two or more minutes.With the complete orchestra, the highest peaks were found to lie in the region between 2,000 and 4,000 c.p.s. The greatest peaks below 64 c.p.s. were obtained when the bass drum was prominent, while the greatest peaks above 8,000 c.p.s. were very plainly due to the cymbals.