The usage of letters in medieval and early modern texts was not, however, entirely consistent. In particular, as in other northern Italian languages, the letters and were often used interchangeably for both voiced and voiceless sounds. Differences between earlier and modern pronunciation, divergences in pronunciation within the modern Venetian-speaking region, differing attitudes about how closely to model spelling on Italian norms, as well as personal preferences, some of which reflect sub-regional identities, have all hindered the adoption of a single unified spelling system.