Vocal imitations of basic auditory features

Abstract

We recently showed that vocal imitations are effective descriptions of a variety of sounds (Lemaitre and Rocchesso, 2014). The current study investigated the mechanisms of effective vocal imitations by studying if speakers could accurately reproduce basic auditory features. It focused on four features: pitch, tempo (basic musical features), sharpness, and onset (basic dimensions of timbre). It used two sets of 16 referent sounds (modulated narrow-band noises and pure tones), each crossing two of the four features. Dissimilarity rating experiments and multidimensional scaling analyses confirmed that listeners could easily discriminate the 16 sounds based the four features. Two expert and two lay participants recorded vocal imitations of the 32 sounds. Individual analyses highlighted that participants could reproduce accurately pitch and tempo of the referent sounds (experts being more accurate). There were larger differences of strategy for sharpness and onset. Participants matched the sharpness of the referent sounds either to the frequency of one particular formant or to the overall spectral balance of their voice. Onsets were ignored or imitated with crescendos. Overall, these results show that speakers may not imitate accurately absolute dimensions of timbre, hence suggesting that other features (such as dynamic patterns) may be more effective for sound recognition.