This study revealed the modes of communication employed between the members of a professional string quartet during rehearsal and performance. Results of this study enabled comparison with modes of communication employed by a student jazz sextet revealed in a previous study by the first author. Six modes of communication were revealed in both studies (i.e., verbal and non-verbal, instruction/cooperation/ collaboration). Results indicated that the modes of communication employed by both groups of musicians (i.e., the string quartet and the jazz sextet) were the same, although, at times, the content of the communication differed based on the presence of a precomposed score and conventions of the musical genre. Participants in both studies confirmed researcher interpretations of the modes of communication during member checks. Results also indicated that when playing from a pre-composed score the string quartet were able to become empathetically attuned and produce ‘spontaneous musical variations’ during performance. The authors propose that these spontaneous musical variations are examples of ‘empathetic creativity’.