Robert C. Maher
Dept. of Elec. Eng., Univ. of Nebraska, 209N WSEC, Lincoln, NE 68588-0511
James W. Beauchamp
Univ. of Illinois at Urbana--Champaign, Urbana, IL 61801
Estimation of the fundamental frequency (F0) of quasiharmonic signals is an important task in musical acoustics. Many existing techniques have unsatisfactory performance due to octave errors, noise perturbations, and other artifacts encountered in practice. Our work in this area, begun in 1986, uses the quasiharmonic assumption to guide a search for an estimated F0, based on the McAulay--Quatieri short-time spectrum measurement procedure. Estimation of F0 involves a two-way mismatch calculation where the discrepancy between the measured partial frequencies and a harmonic search grid is used to refine the F0 estimate. Inaccuracies present in the measured partial frequencies are averaged over all the available partials, thereby improving the F0 prediction. A heuristic weighting scheme is used to help reduce the susceptibility of the procedure to noise or partials missing in the spectral data. The frequency search strategy has also been extended to fundamental frequency estimation of duet (two voice) polyphony. Results for F0 tracking of solo and duet recorded musical instrument passages will be demonstrated.