Loudness levels (LL) of musical scale segments playedpianissimoandfortissimowere predicted for 11 orchestral instruments, using Zwicker’s and Stevens’ Mark VI procedures for loudness calculation. The results show that the dynamic LL range of musical instruments depends not only on the dynamic sound‐pressure level range, but is also influenced by changes in the spectral envelope that accompany the dynamic gradations of sound. As the sound is played louder, its bandwidth extends to high frequencies, and the increase in sound‐pressure level (SPL) is greater for the high partials than for the low ones. Due to spectral loudness summation, the changes in spectral envelope with playing level enhance the dynamic LL range of the sound. As a consequence, for most instruments the dynamic LL range in a given pitch register is larger than the dynamic SPL range in that register. The difference between the two ranges was found to be greatest for brass instruments and for the clarinet, and approached about 6 dB in certain pitch registers.