Effects of humidity on natural gut harp strings

Abstract

Natural gut harp strings are notoriously sensitive to changes in humidity, but the nature of this sensitivity is poorly understood. The results of some recent measurements will be presented, in which a number of well-settled strings were held at constant temperature and subjected to changes in humidity. It will be shown that there appears to be some form of coupling between humidity-induced changes in the string linear density and its tension. Moreover, these changes in linear density and tension largely cancel out, with little net effect on the string frequency. It appears, instead, that the major effect of changes in humidity is to trigger episodes of additional string creep. The longevity of gut harp strings may therefore be determined as much by their propensity to creep as by their breaking strength.