Method and apparatus to modify pitch estimation function in acoustic signal musical note pitch extraction

摘要

In one aspect thereof this invention provides a method to estimate pitch in an acoustic signal. The method includes initializing a function ƒ_t and a time t, where t=0, x′₀=ƒ₀(F₀), x′₀ is a pitch estimate at time zero and F₀ is a frequency of the acoustic signal at time zero; determining at least one pitch estimate using the function x′_t=ƒ_t(F_t) by an iterative process of creating ƒ_t+1(F_t+1) based at least partly on pitch estimates x′_t, x′_t−1, x′_{t−2, x′t−3}, . . . , and functions ƒ_t(F_t), ƒ_t−1(F_t−1), ƒ_t−2(F_t−2), ƒ_t−3(F_t−3) . . . and incrementing t; and calculating at least one final pitch estimate. Embodiments of this invention can be applied to pitch extraction with various different input acoustic signal characteristics, such as just intonation, pitch shift in the frequency domain, and non-12-step-equal-temperament tuning.