Strengths of ENV and TFS coding in response to SFM at different modulation rates and depths. A, ENV-following response (peak height of the Sumcor at 0; see Materials and Methods) for each unit as a function of modulation rate, 2, 5, and 10 Hz, for a fixed modulation depth of 32%. B, TFS-following response (peak height of the Difcor at 0) for each unit as a function of modulation rate, 2, 5, and 10 Hz, for a fixed modulation depth of 32%. C, Envelope-following response for each unit as a function of modulation depth: 2, 4, 8, 16, and 32%, for a fixed modulation rate of 5 Hz. Significant differences (p < 0.05) are indicated by asterisks. D, TFS-following response for each unit as a function of modulation depth, 2, 4, 8, 16, and 32%, for a fixed modulation rate of 5 Hz.