All together now: String quartets have been found to operate under a form of “unspoken leadership” also exhibited in many animal communities
“There are two golden rules for an orchestra,” the conductor Thomas Beecham is said to have remarked. “Start together and finish together. The public doesn’t give a damn what goes on in between.” Beecham was prone to witty overstatement, but his statement fits the intuition that we are acutely sensitive to failures of synchronisation in musical performance. “They were all over the place” is the typical put-down of ensembles with sloppy timing.
Yet playing together in time is far from trivial. Even orchestral musicians watching a conductor have to be anticipating the beat if they’re not going to miss it, and the smaller ensembles have no human metronome to follow. Besides, ensembles, just like solo performers, slow down and speed up for expressive purposes. Who decides this when there is no one obviously leading?
That’s a question being studied by psychologist Alan Wing and Satoshi Endo at Birmingham University, together with cellist Adrian Bradbury. At the Aldeburgh festival in June, Wing will describe his experiments with the Signum Quartet, a German ensemble which is also performing at the festival. Signum has gamely agreed to be the guinea pig for Wing’s studies of musical synchronisation.
Synchronisation to a regular pulse is an old topic: the Dutch scientist Christiaan Huygens observed in the 17th century that two pendulum clocks fall into sync if “coupled” by being attached to the same wooden beam. Coupling via visual feedback is all it takes for a treeful of flashing fireflies to fall into step. We do this ourselves unconsciously as we walk side by side—a fact that, overlooked by architects, initially left the Millennium bridge over the Thames dangerously prone to big undulations as the vibrations created synchrony between the footsteps of pedestrians.
Yet conscious synchrony of human actions can be hard to sustain: we’re apt to drift in and out of time. Some years ago Wing investigated how rowers in the Cambridge Blues all pulled together, and he hints with tongue in cheek that those studies might have helped stem the previous run of Oxford victories. But rowing, with everyone striving to synchronise an identical and highly regular action, is easy compared with music. In a string quartet, each musician plays a different part, and yet they must all intermesh to create a single rhythmic pulse, albeit one that satisfies the elastic demands of musical expression. Who is following whom?
To find out, Wing tracked the movements of the Signum musicians using motion-capture video, which bounces infrared light off reflectors attached to their bows. Electronic pick-ups on the instruments then allowed him to follow the relationships between movement and sound for each player in turn, and to look for correlations between the players. Previous work, particularly on keyboardists, has shown that performers don’t keep to a strict tempo but vary the gaps between beats by perhaps a few milliseconds. Some of these variations are random, but some are intentional and repeatable from one performance to another. Such variations not only convey emotion but also, paradoxically, help the listener discern the music’s pulse by exaggerating rhythmic patterns.
In string quartets, the performer who carries the melody—often the first violin—is usually deemed to be the leader. But do their microscopic variations in timing bear that out—do the other players, for example, fall in step slightly behind the first violin? That’s what Wing’s results suggest. By using mathematical techniques analogous to those used to study periodic change in climate and animal populations, he analysed the timings of each player during a passage from Haydn to figure out whether any one player’s rhythm depended on that of any other. It seems that the cello and viola form a tight-knit “rhythm section,” like the bass and drums of a rock band, which responded to but did not in turn affect what the first violin was doing.
Mindful of Beecham’s dictum, Wing also wondered just how ensembles begin a piece. The lead player in a quartet will usually make an exaggerated movement of the bow or head to signal the first beat, but what exactly is it that the other players respond to? Wing created a virtual avatar of the first violinist, from which he could lop off the head or an arm to see how much it influenced the other players as they watched the screen. As intuition suggests, the head and the right (bowing) arm were crucial, while the left (fingering) arm didn’t really matter. And the tempo adopted by the ensemble seemed to be set by the acceleration of these initial gestures.
In a sense, this is an extreme example of the kind of “unspoken leadership” that has been studied in animal communities, for example in the question of how just a few honeybees with “privileged information” about the location of a good nest site can induce the rest of the swarm to follow them. It’s possible, then, that the ramifications extend beyond the togetherness of musicians: to that of dancers and acrobats, even to the socially cohesive group activities involved in agriculture and industry—in which some think music has its origins.
