In the 1970s, reports emerged that many aspects of “natural” sounds (e.g. envelope or pitch changes) exhibit “1/F” spectra (Voss & Clarke, 1975, Nature 258:317). Human listeners reportedly prefer “random melodies” where the pitch varies according to a 1/F spectrum to melodies with faster (1/F0) or slower (1/F²) dynamics (Voss & Clarke 1978, JASA 63:258). It therefore seems natural to conjecture that neurons in the central auditory system may exhibit some preference for 1/F dynamics, particularly as Yu et al reported 1/F tuning in primary visual cortex (SfN abstr. 2003 338.2). To test whether neurons in primary auditory cortex (A1) exhibit tuning to 1/F dynamics we generated random tone complexes with frequency components at 1/2 octave intervals from 0.5 to 24 kHz, in which the fundamental frequency and the envelope fluctuated as a function of independent 1/Fx random walks”, with exponent x set to values between 0.25 (rapid fluctuations) to 4 (slow fluctuations). We recorded responses to 30 s segments of th...