The following paper presents spectrographic data of consonant sequences containing one or two consonants omitted and/or changed into another consonant when compared to an existing perception analysis. In most cases, perceptual and acoustic data are shown to strongly correspond, proving that consonants had indeed been changed, significantly reduced or deleted, mainly in a weak position, thereby preserving acoustic information crucial for lexical access, integration of prosodic structure and successful communication. Tentative rules summarise the tendencies observed in reduction and assimilation patterns.