The way harpsichord strings are plucked depends on the mechanical and geometrical properties of the plectrum, which influence is expected on the sound (initial conditions of string vibration) and touch (mechanical reaction of the key). In harpsichord making and setup, the "voicing process" consists in selecting and shaping the plectra in order to provide the instrument with interesting sound features and homogeneity of sound and touch over the whole tessitura. This article presents a perceptual test investigating how different voicings are perceived. Experienced harpsichord players took part in a free playing and verbalisation task and evaluated two different sets of plectra. The verbal data was analysed with methods inherited from the field of psycholinguistics. A perceptual characterisation of each set of plectra was obtained, based on evaluations of loudness of the sound, hardness of the plectra, strength of the voicing, length/resonance, dynamics, equality and evolution of sound and touch over the tessitura. This perceptual characterisation was compared to physical measurements (minimum triggering force on the key, equivalent sound level) made during or after the tests. The main difference between the two voicings was the loudness of the sound (in agreement with the equivalent sound level) and the hardness of the plectra (in agreement with the minimum triggering force). More in general, this study validates the adequacy and relevance of the free playing and verbalisation method applied to musical instruments involving multimodal perception.