Whether a sound is voiced or unvoiced is itself one aspect of the manner in which it is produced, but the term is most often applied to the differentiation between plosive, nasal, fricative, affricate, tap or flap, approximant. Each of these classification of sound affords cues which are self-evident from the spectrographic features already mentioned in section 2.2.4 and they can therefore be used to verify the features of consonant sounds by non-native learners.
