T HE E FFECT OF M ICROTIMING D EVIATIONS ON THE P ERCEPTION OF G ROOVE IN S HORT R HYTHMS MATTHEW DAVIES INESC TEC, Porto, Portugal G UY MADISON Umeå University, Umeå, Sweden P EDRO S ILVA &FABIEN G OUYON INESC TEC, Porto, Portugal GROOVE IS A SENSATION OF MOVEMENT OR WANT- ing to move when we listen to certain types of music; it is central to the appreciation of many styles such as Jazz, Funk, Latin, and many more. To better understand the mechanisms that lead to the sensation of groove, we explore the relationship between groove and systematic microtiming deviations. Manifested as small, inten- tional deviations in timing, systematic microtiming is widely considered within the music community to be a critical component of music performances that groove. To investigate the effect of microtiming on the perception of groove we synthesized typical rhythm patterns for Jazz, Funk, and Samba with idiomatic microtiming deviation patterns for each style. The mag- nitude of the deviations was parametrically varied from nil to about double the natural level. In two experi- ments, untrained listeners and experts listened to all combinations of same and different music and micro- timing style and magnitude combinations, and rated liking, groove, naturalness, and speed. Contrary to a common and frequently expressed belief in the liter- ature, systematic microtiming led to decreased groove ratings, as well as liking and naturalness, with the excep- tion of the simple short-long shuffle Jazz pattern. A comparison of the ratings between the two listener groups revealed this effect to be stronger for the expert listener group than for the untrained listeners, suggest- ing that musical expertise plays an important role in the perception and appreciation of microtiming in rhyth- mic patterns. Received: January 30, 2012, accepted November 3, 2012. Key words: groove, microtiming, movement, rhythm, listening experiment G ROOVE IS A CENTRAL ASPECT OF MUSIC PER- ception and appreciation, closely connected to the main functional uses of music; namely, dance, drill, and ritual. When seeking to find a relation- ship between music and the behavior that groove induces–synchronization and coordination–the tempo- ral properties of the music signal might be crucial to our understanding of groove. To work towards a formal definition of groove, Janata, Tomic, and Haberman (2012) asked subjects participat- ing in a synchronization experiment to provide their own written descriptions. Based on an analysis of fre- quently occurring words given by the participants, the authors derived the following definition: ‘‘Groove is that aspect of the music that induces a pleasant sense of wanting to move along with the music’’ (p. 56). This crowd-sourced definition bears strong similarities to the operational definition given by Madison (2006): ‘‘want- ing to move some part of the body in relation to some aspect of the sound pattern’’ (p. 201)—a definition that we follow in this paper. Since groove is a pleasant and attractive feature of music, one goal of this research is to understand the physical properties so that we can, in some way, add groove to music. Given that people syn- chronize movement to musical stimuli (Pressing, 2002), in addition to the utilitarian aspect of putting knowl- edge of groove to some purpose, we are also interested in the fundamental question of the role of groove in music. A central issue to consider is what physical prop- erties affect the sensation of groove. While these phys- ical properties are presently unknown, the relationship between groove and some global aspects of music sig- nals has been examined; for example, tempo (Janata et al., 2012), musical style (Janata et al., 2012; Madison et al., 2011), rhythmic patterning and timbre (Zeiner- Henriksen, 2010), and beat salience and event density (Madison et al., 2011). In this paper we test a musical property related to performance and expression: micro- timing deviations. A key feature of human performance of music is var- iability. Expression in music performance can be dem- onstrated through timing, dynamics, timbre, and pitch, inasmuch as the instrumentation allows for that (for a review, see Gabrielsson, 1999). Indeed, expression in the Music Perception, VOLUME 30, ISSUE 5, PP. 498–511, ISSN 0730-7829, ELECTRONIC ISSN 1533-8312.  2013 BY THE REGENTS OF THE UNIVERSITY OF CALIFORNIA ALL RIGHTS RESERVED. PLEASE DIRECT ALL REQUESTS FOR PERMISSION TO PHOTOCOPY OR REPRODUCE ARTICLE CONTENT THROUGH THE UNIVERSITY OF CALIFORNIA PRESS ’ S RIGHTS AND PERMISSIONS WEBSITE, HTTP:// WWW. UCPRESSJOURNALS . COM/ REPRINTINFO. ASP. DOI: 10.1525/ MP.2013.30.5.498 498 Matthew Davies, Guy Madison, Pedro Silva, & Fabien Gouyon