Recent empirical investigations suggest that music performance and perception can evoke a collective cardiac response in performers and audience members, and interpersonal cardiac coupling can be related to musical features. However, the relationship between musicians’ and audiences’ cardiac responses is poorly understood. This study investigates the interpersonal cardiac coherence of selected audience members and performers from the Stavanger Symphony Orchestra and the Norwegian Radio Orchestra during multiple performances of Harald Sæverud’s Kjempeviseslåtten. The cardiac coherence index (CCI) was computed by applying the intrinsic synchrosqueezing transform to the cardiac interbeat interval of each signal, combining noise-assisted multivariate empirical mode decomposition and short-time Fourier transforms. The results show that the CCI values among the audience members were stronger than those of the musicians. Sound pressure level measurements predicted the musicians’ CCI values, whilst musical form structure predicted the audiences’ CCI values. These results advance our understanding of how cardiac rhythms support interpersonal interactions and contribute to research on live orchestra performances.