Very few studies have directly investigated aspects of the quality of a piano performance and considered how this might relate to hand span. One study (Lee, 1990) found hand ergonomic variables were not correlated with performance quality measures (dynamic and temporal evenness). However, the excerpts chosen (a simple five finger exercise and an arpeggio) did not involve wide stretches or leaps, thus this lack of association in relation to finger spans is perhaps not surprising. Female pianists appear to be far less disadvantaged, if at all, when performing baroque or early classical repertoire such as Bach and Mozart, as the musical figures tend to fall naturally ‘under the hand’ even for those with small hands. (See Gender differences in major competitions and performing careers)
While not specifically about hand size, an article by Goebl & Palmer (2013) provides firm evidence of the link between the efficiency of wrist/hand/finger movements and performance quality. They measured quality in terms of accuracy and precision of timing and tonal intensities. Small-handed pianists exhibit far greater movement of their hands and wrists, and make more leaping and slanting strokes in order to reach notes, compared with large-handed pianists. The reduction in movement can be readily felt by pianists transferring to a keyboard more compatible with their hand size.
The detailed work of Otto Ortmann early last century supports the notion that pianists with ‘small hands’ are handicapped in many ways. See: Principles of ergonomics and biomechanics. There is now very strong anecdotal evidence of improved quality of performances when a pianist can play a keyboard that best suits their hands. This evidence comes from the growing number of pianists who have experienced alternatively sized keyboards. See: Feedback from pianists
Other anecdotal evidence of the benefits of a large reach combined with narrower keys come from this description of the capabilities of the 19th century composer, Carl Maria von Weber:
‘One of the great orchestrators of the day, Weber was also aware of the new tonal possibilities of the piano, especially of the Viennese instrument he favoured (a Brodmann). This was lighter than a modern instrument, and its keys were narrower, with an octave span of 15.9 cm as against the modern 16.5 cm. Moreover, an engraving shows that Weber had long fingers and an exceptionally elongated thumb that reached to the middle joint of his index finger: this enabled him to play four-part chords covering a 10th without difficulty, and to devise for himself spectacular leaps and the octave glissando of the Konzerstück. As Benedict described it: ‘Having the advantage of a very large hand, and being able to play 10ths with the same facility as octaves, Weber produced the most startling effects of sonority and possessed the power, like Rubenstein, to elicit an almost vocal quality of tone where delicacy or deep expression were required.’
(Oxford University Press, 1980).
Goebl, W. & Palmer, C.F. (2013). Temporal control and hand movement efficiency in skilled music performance. PLOS ONE, 8 (1). www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0050901
Lee, S-H. (1990). Pianists’ hand ergonomics and touch control. Medical Problems of Performing Artists, 5 (2), 72-78.
MacRitchie, J. (2015). The art and science behind piano touch: A review connecting multi-disciplinary literature. Musicae Scientiae, 19 (2), 171-190.
Ortmann, O. (1929). The Physiological Mechanics of Piano Technique. Kegan Paul, Trench, Trubner & Co., London, and E.P. Dutton & Co., Inc., New York.
Oxford University Press (1980). The New Grove Dictionary of Music and Musicians Vol 20, pp. 250-251, London.