Frequency of the timing feature versus the peak frequencies of L₁ and L₂ for seven observations of Cyg X-1 with a clear signature of the timing feature (marked in Table C.1). The frequency of the feature is parameterized by the peak in the hard time lag, assuming a systematic uncertainty of 0.1 Hz. Uncertainties on the Lorentzian frequencies and Γ are at the 90% confidence level. The frequency of the feature correlates positively with the position of the Lorentzians, which are known to increase in frequency as the source softens.