NORMALISATION
المؤلف:
John Field
المصدر:
Psycholinguistics
الجزء والصفحة:
P191
2025-09-20
333
NORMALISATION
Applying a standard interpretation to material which contains non standard features. Especially used for the way in which a listener matches highly variable speech input to a set of phoneme values.
The assumption is often made that phonological representation consists of ‘core’ or prototypical phoneme values stored in memory. The question then arises of how one is able to identify phonemes in connected speech when they often diverge enormously from this core value. And how is one to edit out the many features in the speech signal (some individual to the talker) which do not contribute in any way to the task of phoneme identification, and may even obscure it?
It is assumed that listeners edit (normalise) the material in the speech signal in order to achieve a ‘best match’ with the standard phoneme values stored in their minds. In the process of editing, irrelevant features are suppressed. These might include features that are:
specific to the talker: characteristics of the talker’s voice, the talker’s accent or the talker’s individual speaking style;
specific to the environment, e.g. hiss on a recording;
specific to the phonological context in which a phoneme appears.
Such features were initially assumed to interfere with the matching task and were treated as ‘noise’. However, if they were completely deleted from the record, then they could not be transferred to long term memory. This cannot be what happens since we succeed extremely well in recalling the characteristics of individual voices. It was therefore suggested that the phonetic information in the input is processed separately and at a different level of attention from the indexical information relating to voice type and quality.
Recent research has raised questions about this view of normalisation. There is now considerable evidence that phonetic information and indexical information are more closely linked in the listening process than was supposed: for example, words are identified more quickly if they are heard in a known voice. It appears that the indexical features of a talker’s voice are encoded in memory together with the linguistic message.
Some commentators have questioned the long-held assumption that we match widely variant input to a set of standard values. They suggest that phonological representation is much more detailed, taking the form of multiple traces of all the encounters we have had with a particular phoneme. We are thus able to match the input directly to a previously encountered variant of a phoneme, without recourse to a normalisation process that involves editing what we hear. Among the details stored may be representations of an individual talker’s accent and of their personal speech characteristics.
Even if one accepts this view, there still remain ways in which a listener needs to accommodate to a talker. The term ‘normalisation’ is also used for a process whereby a listener adjusts their analysis of a speech signal in order to take account of characteristics of the voice of the speaker, including accent, loudness, speech rate and intonation patterns. The most obvious example is when meeting somebody whose voice or whose accent is unfamiliar. The pitch of the speech signal appears to provide information about the size and shape of the speaker’s vowel tract– information which influences a listener’s interpretation of the sounds they hear.
Similarly, listeners make fine judgements based upon an assessment of the rate at which a talker is speaking. Experiments in which slow speech is inserted into a more rapid utterance have shown that articulation rate contributes importantly to phoneme identification. Judgements of this type cannot be based upon a talker’s average speech rate, but must be revised from moment to moment during a conversation.
See also: Phonological representation, Speech perception: phoneme variation
Further reading: Johnson and Mullenix (1997)
الاكثر قراءة في Linguistics fields
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