Phonemes are small segments of speech sound such as the 'aye' sound in AI. Phoneme labelling is the stage within speech recognition of taking individual phonemes in a speech source and labelling them with the appropriate phonem tag. Typically for vowels this is laregly about the frequency distrubution, but for cosonants the shape of the sound is important, particularly the ''attack', the way the sound starts. This is made more complex as it can be hard to separate the phonemes in the aydio stream and also because the precise qualities of one phoneme often vary depending on the immediately preceding one. Phineme labelling was one of the early uses of Kohonen networks.
Used in Chap. 6: page 93