The principles of the IPA

The IPA, like any system that is used for analysis, makes some assumptions about the nature of speech. Not all of these assumptions are shared by all phoneticians, but it is important none the less to understand them. They are set out in the IPA Handbook (IPA 1999: 3–4).

According to the IPA, ‘Some aspects of speech are linguistically relevant whilst others … are not.’ Phonetic transcriptions should only contain information that is linguistically meaningful.

If two speakers from the same speech community say the same thing in the same accent (for instance, ‘Come in!’), then they will none the less sound different, although we recognize them as saying the same thing. Physical differences, caused by things such as gender, age or physical state (like being out of breath), mean that people sound different; but these are physical, not linguistic, differences, so a phonetic transcription does not capture them. Except in clinical situations, phonetic transcriptions generally ignore speakers’ individual quirks, preferring to work on the language of a community, and not just of an individual.

On the other hand, think about ways of saying ‘Shut up!’: in particular, how are the two words joined? In the north west of England, you might hear a [ɹ] sound (as if it were written ‘shurrup’); in many parts of the English-speaking world, you will hear a glottal stop, [ʔ], or a tap, [ɾ] (as in ‘shuddup’, defined in the online Urban Dictionary as ‘what Donald Duck says to Goofy Dog’). In most places, you could hear an alveolar plosive with a puff of air (aspiration), [th ]. Most speakers will have a choice about how to join these words, with [th ] probably being the sound that has the highest social status. These differences are certainly socio-linguistically meaningful, and for that reason, phoneticians want to be able to represent them.

Secondly: ‘Speech can be represented partly as a sequence of discrete sounds or segments.’ ‘Segment’ means a piece of something that has been chopped up: in the case of speech, ‘segments’ means a piece of the speech signal, which is actually continuous. This is the principle that makes the use of the IPA alphabetic: the claim is not that speech is made of segments, but that we can represent it as segments. It is a useful working assumption in many ways, and it is familiar to people who use an alphabetic writing system.

Thirdly: the IPA establishes two major types of segment, consonant and vowel. Consonants are those sounds which are produced with some kind of constriction in the vocal tract. We can feel, see and hear where these constrictions are made, and what kind of constriction they are.

Vowels, by contrast, are produced without a constriction in the vocal tract, and it is harder to sense how they are articulated. The IPA’s terminological framework for describing consonants and vowels is different.

Suprasegmentals are aspects of speech which persist over several segments, such as duration, loudness, tempo (speed), pitch characteristics and voice quality; they are often thought of as the ‘musical’ aspects of speech, but may include other properties like lip-rounding. They are called suprasegmentals because they function over (‘supra’ in Latin) consonants and vowels.

The effect of suprasegmentals is easy to illustrate. In talking to a cat, a dog or a baby, you may adopt a particular set of suprasegmentals. Often, when doing this, people adopt a different voice quality, with high pitch register, and protrude their lips and adopt a tongue posture where the tongue body is high and front in the mouth, making the speech sound ‘softer’.

Suprasegmentals are important for marking all kinds of meanings, in particular speakers’ attitudes or stances to what they are saying (or the person they are saying it to), and in marking out how one utterance relates to another (e.g. a continuation or a disjunction). Both the forms and functions of suprasegmentals are less tangible than those of consonants and vowels, and they often do not form discrete categories.