We investigate determinants of Koszul complexes of holomorphic functions of a
commuting tuple of bounded operators acting on a Hilbert space. Our main result
shows that the analytic joint torsion, which compares two such determinants, can be
computed by a local formula which involves a tame symbol of the involved
holomorphic functions. As an application we are able to extend the classical tame
symbol of meromorphic functions on a Riemann surface to the more involved setting
of transversal functions on a complex analytic curve. This follows by spelling out our
main result in the case of Toeplitz operators acting on the Hardy space over the
polydisc.