In the tonal musical practice, different intervallic relationships between pre-terminal and terminal harmonies may be interpreted as preparations of closure. The available substitutions of closural progressions include plagal and authentic progressions, the latter further including octatonic substitutes of the dominant as captured e.g. by Tonfeld theory (Haas, 2004). The cognitive and perceptual reality of all these substitutes, however, has never been empirically tested. To address this, we generated tonally closed and open chord progressions (in seventh-chord voicings) in the Jazz idiom wherein pre-terminal harmonies were systematically transposed away from the global key. 150 participants were asked to listen to these progressions and to predict the number of chords required for a given progression to achieve closure. With a novel analytical approach that quantifies the convergence of response patterns, we can estimate the likelihood for a pair of progressions to be perceived as substitutions of one another. Interestingly, we observed the so-called “frontdoor” and “backdoor” progressions to be the most substitutable pair. Other idiomatic substitutions were not perceived as such, but rather as preparations of harmonic goals different from the global tonic. However, substitutes predicted by music theory were relatively more likely to be perceived as mutual substitutions than any other pair among the tested transpositions. These results capture the complex relationship between a music-theoretical phenomenon, such as harmonic preparation, and the corresponding perceptual phenomenology in the broad population, where perception is mediated by idiom-specific familiarity and a plethora of interconnected musical features.