A snippet in a snippet: Development of the Matryoshka principle for the construction of very short musical stimuli (plinks)

Abstract

For the past 140 years, numerous studies have been conducted to examine minimum durations of samples needed for the recognition of acoustic parameters such as pitch, timbre or vocal phonemes. Recent studies in this field are often based on short clips (plinks) of popular songs, using target variables such as titles and interpreters. These studies provide strong evidence that a wide range of intra- and extramusical information can be identified above chance level for stimuli lasting much shorter than a second. Nevertheless, a review of precedent studies revealed a heterogeneity in stimulus generation processes that could have influenced overall recognition rates. As a piece of music unfolds in time, its timbral structure is subject to a variety of changes. We assume that the position of stimulus extraction, therefore, could influence the outcomes of a subsequent recognition task, for instance. In this study, we offer a systematic and objective stimulus extraction procedure that might help to control for (a) a possible confounding of stimulus duration and timbre (caused by the extraction of stimulus sets of various length from different song positions), (b) possible confoundings of song section and timbre (caused by the comparison of stimulus sets from divergent song sections), and (c) the suspected influence of subjective criteria on extract selection (caused by the non-randomized selection of extract positions). As an alternative approach, the suggested Matryoshka principle produces randomized sets of nested stimuli controlled for song position and objective selection. Each set represents an individual section and consists of five short excerpts, cut from each other in decreasing duration. Correlation analyses confirmed that these sets prove to be stable in terms of their mel-frequency cepstrum coefficients, the so-called “psycho-acoustic fingerprint” of a sound. Based on the software Random Plink Generator, the suggested procedure can help to contribute to an objective selection of stimuli in future plink research.