Application of Bedrosian Condition to Pitch-Shifting Performace Evaluation for Chirp Sounds

It is assumed that for a certain class of sounds there exists a relationship between their pitch and their complex dynamic representation - CDR in polar-form (real-valued log-envelope and instantaneous frequency). The CDR processing appears a powerful means for pitch shifting of chirplike sound signals fulfilling practically the assumption of the Bedrosian theorem. Scaling the CDR components can be used, e.g., in a generator of different melodies of calling signals, where the sound of each note in a melody is derived from a short recording of a voice of a chosen creature. For this aim a concept of a Bedrosian chirp is proposed whose local instantaneous amplitude and complex phasor spectra are separated. For the first time a quantitative measure to estimate and predict the quality of sound processing using the CDR scaling is introduced and its utility verified by experiments with real-life audio chirps.