A quantitative model of cross-speaker pitch range equivalence

D. R. Ladd, Edinburgh University

This paper is a preliminary presentation of a quantitative model that

predicts the relative F0 level of tone phonemes produced by different

speakers. F0 values are modeled in terms of three parameters, "level" and

"span" (speaker-specific parameters referring to the overall level of the

voice and the span or range of frequencies used by the speaker) and "tone"

(phonologically specified levels within the speaker's overall range, for

e.g. H, M and L tone). The basic form of the model is F0 = Fr + S^T,

where Fr (reference frequency) is a reference level at the bottom of the

speaker's range, T can take one of a restricted range of values

corresponding to the tones of the language (e.g. L tone has T = 1 and H

tone has T = approximately 1.45), and S (span) is a variable that models

the F0 difference between H and L tone. This model is shown to give a

very close fit to mean tone values for 5 speakers of a 4-level-tone

language (Mambila) and 4 speakers of a 3-level-tone language (Yoruba). For

Yoruba, the model also clearly shows that overall raising of pitch range

in questions is a change in overall level (Fr) rather than span (S), and

that raising of H tones before L tones is clearly a change in span (S)

rather than in the linguistic tonal specification (T).