Effect of reverberation on instrumental vibrato tones

Abstract

Musical vibrato is the process by which a performer subtly varies the frequency and amplitude of a note for expressive effect. Previous work has suggested that the vibrato modulation may not be uniform across all overtones, causing the individual frequency trajectories to become decorrelated. In this study, we investigate the effect of reverberation on instrumental tones performed with vibrato. This is accomplished by performing a detailed time-frequency analysis to extract the instantaneous frequencies of many overtones. In order to accurately track the low amplitudes of the upper harmonics, we present an algorithm tailored for optimal tracking in as little as 10 dB SNR. For tones recorded in an anechoic environment, the instantaneous frequency modulations of all the overtones are found to be highly correlated. However, tones recorded in a reverberant space, as well as anechoic recordings processed with a synthetic reverberation are found to have significantly lower correlations between the overtones. In addition to providing insight into musical timbre variations, these results could be useful for characterization of acoustic transfer functions or applications where overtone correlation is assumed, such as audio source separation.