A quadratic phase interpolation method for synthesis of musical tones incorporates both phase and frequency measurements at the boundaries of a data frame using a weighted least square algorithm approach. The approach assumes that the true frequency and phase at the two ends of a data frame conform to a quadratic phase model and that exact match between measured phase and frequency with the quadratic model is not necessary because of the noise in the measurements.
Frequency and phase interpolation in sinusoidal model-based music and speech synthesis