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so that their potential combination is excluded by definition.

In the first version of the VPA (1981) Laver distinguished between 'Vhispery' and 'Breathy' phonation types. Although he recognised there was a close auditory relationship between them, and they could be considered auditorily at different points of a continuum, he suggested the physiological differences in how they were produced warranted a differentiation between them.

In 'Vhispery' voice, phonation would be produced with a greater degree of laryngeal effort, more specifically, with increased Medial Compression (Fig. 4, p. 36), to achieve a greater amount of glottal friction, which would be more prominent than in ’Breathy’ voice. Breathy voice would be produced with minimal adductive tension, extremely weak medial compression and low longitudinal tension (Laver,1980). The modal, periodic component of the voice would be more prominent in breathy voice than in whispery voice, which would show either equal degrees of audible friction and modal voice, or more friction.

Whereas we would be able to perceive 'Compound Phonation Types' such as 'Vhispery voice', 'Vhispery Creak', And 'Vhispery falsetto' because they are all produced with high degrees of medial compression. 'Breathy' voice could not combine with any other phonation type except modal voice, i.e. not with falsetto nor 'creak' as it is produced with very low medial compression (Laver, 1980).

This difference in definition between 'whispery' and 'breathy' voice quality may be illustrative of the physiological correlates of the commonly used gross dichotomy in describing abberrant voice quality as 'Hyperfunctional' or 'Hypofunctional' (Hammarberg, 1986, Hillman et al, 1989, Rammage et al, 1992). 'Vhispery' voice would be associated with a degree of effort (Hyperfunction) with increased medial compression giving rise to a posterior glottic chink and audible turbulence. 'Breathy' voice would be associated with low degrees of adductory tension and medial compression (Hypofunction) with or without a posterior glottic chink.

The most common physiological correlate of 'breathy' voice is a persistent posterior glottal chink between the arytenoids. This has been found to be common especially in women, without being perceptually abnormal. (Sodersten and Lindestad, 1990, Sodersten et al, 1994, Biever and Bless, 1989, Rammage et al, 1992)

'...several sources of glottic and supraglottic factors influence

perceptual voice characteristics, including those of 'breathiness'.

The relative contribution of turbulent airflow through a posterior

glottic chink jnay be small. '

In the current version of the 'Vocal Profile Analysis Protocol' (Edinburgh, 1986), (Fig. 10, p. 83), the breathy and whispery phonation types have, however, been merged and only appear as 'Vhispery'. 'Vhispery' and 'Breathy' are now considered on a continuum of medial compression, whisper having high, breathy voice low, but both having low adductive tension giving rise to degrees of posterior glottic chinks.

Using one term to describe breathy phonation seems to make sense. The rating of degrees of laryngeal tension or laxity in the VPA, help differentiate ('Hyperfunctional' and 'Hypofunctional') voices with degrees of glottal air leakage as described above. Whether 'Vhispery' is the term that best describes this feature, and is most widely understood, is debatable. It highlights the need however, for objective measurements to complement perceptual evaluation and reduce the number of impressionistic labels used.

Laver (1980) describes Harsh voice as a variety of Modal voice. The pitch may be normal (Michel, 1964) or close to the bottom of the modal range and there is a greater amount of aperiodicity of vocal fold vibrations (Vendahl, 1963, Zemlin, 1964, Michel, 1964). A physiological correlate of harshness is high laryngeal tension level (Laver, 1980, Milisen, 1957, Van Riper and Irwin, 1958, Kaplan, 1960 and Zemlin, 1964). Harsh voice is produced with greater medial compression and adductive tension than modal voice.

'Creak' has previously been described in detail in the section about 'Vocal Registers'. Laver (1980) recognises the existence of registers but due to ambiguity in the interpretation and understanding of 'register', he prefers to describe falsetto, modal and creaky phonation as 'Phonation types'. He avoids defining phonation types in terms of fundamental frequency because of the previously suggested overlap between the extremes of the low falsetto/high modal voice range and the low modal/high creaky voice range.

Creak or 'vocal fry' tends to be defined in terms of low fundamental frequency. Laver, however, suggests that 'creak' can also be perceived in a falsetto voice and it is a common feature in some speakers of American English and Italian, where it is interspersed throughout the vocal range and used more or less continuously as part of habitual voice production. This was also found by Abberton (1976). This would be described as 'Creaky (modal) voice' as opposed to 'Creak', often used in English at the end of a falling intonation contour to signal the end of a statement.

'Tension settings' are described as

'settings of overall tension,

which exercise their effect throughout the vocal system'. Two broad

Modification in degrees of laryngeal tension in the form of Medial Compression, Adductive and/or Longitudinal tension, (Fig. 4, p. 36) will result in the emergence of perceptions of harshness and/or whisperiness (Laver, 1980).

Laver goes into a great deal of detail describing the effect of tension in the laryngeal, pharyngeal and supralaryngeal vocal tract and describes, for instance, 'tense voice':