Nuclear Accent Shape and the Perception of Prominence Rachael-Anne Knight Prosody and Pragmatics 15 th November 2003

Outline  The perception of pitch  Plateaux and contour shape  Pitch and prominence  The effect of shape on prominence perception  Sound symbolism  Conclusions

The Perception of Pitch - F0  The perception of the pitch of a complex sound is related to the fundamental frequency  Sounds that have a higher fundamental frequency sound higher in pitch

The Perception of Pitch – Syllable Position  In an utterance the position of a syllable also affects the perception of pitch  If two syllables have identical F0, the one later in the utterance will sound higher in pitch Frequency Time  Explained as the listener ‘normalising for declination’

Contour Shape  Real contours are not stylised peaks and troughs  The majority of falling nuclear accents are realised as more of a flat stretch of contour Peak Plateau

Definition of the Plateau  Plateaux are defined as being 4% down from any absolute peak in F0  4% is the range of perceptual equality Peak 4% range Plateau

Segmental and Prosodic Effects on the Production of the Plateau  Plateaux:  Begin earlier in syllables with sonorant onsets  Take up more of syllables that have sonorant onsets and codas  Are aligned later in the syllable in polysyllabic than monosyllabic feet

The End of the Plateau  Some speakers align the end of the plateau earlier in the syllable before a word boundary  The end of the plateau is stably aligned within the syllable regardless of pitch span  More errors made with incorrect EP alignment in a true/false judgment task  The end of the plateau seems to be the real target (rather than the peak) (Knight 2002)

The Function of the Plateau  What is the plateau for?  Why do speakers produce plateaux in nuclear position?  No physiological reason that requires them to produce a plateaux  Perhaps the plateau affects the perception of the pitch (and  the prominence) of the nuclear syllable

Pilot Experiment*  Subjects heard pairs of sentences where nuclear accent differs only in shape (peak vs. plateau) not frequency Knight (2003)

Pilot Experiment*  Subjects heard pairs of sentences where nuclear accent differs only in shape (peak vs. plateau) not frequency  Asked in which version accent sounds higher  73% of responses favoured plateau stimuli Knight (2003)

Pitch and Prominence  “Linguistically, the size of … F0 excursions … correlate with the prominence of the accent”  Gussenhoven and Rietveld (1985:299)  BUT…  “Perceived prominence is related in a complex way to the range of F0 values employed”  Terken (1990:1768)

Prominence Experiment  Hypothesis  Subjects will accept an accent as the most prominent at a lower frequency when there is a plateau (rather than a peak) in the contour Equal Pitch Equal Pitch

Prominence Experiment – Stimuli  Test sentence “Anna came with Manny”  Resynthesised nuclear accent (14 versions)  Frequency: 160, 170, 180, 190, 200, 210, 220 Hz  Shape: peak or 100ms plateau  2 tokens of each version quasi-randomised together

Examples of different contours AnnaManny

Prominence Experiment – Procedure  24 subjects listened to each version over headphones  12 asked “Is ‘Anna’ or ‘Manny’ higher in pitch?”  12 asked “Is ‘Anna’ or ‘Manny’ more prominent?”  Responded by pressing buttons marked A and M on a keyboard 220 Hz. Plateau 220 Hz. Peak

Prominence Experiment- Statistics  Probit analysis  To identify the cross-over point for each series for each subject (where ‘Anna’ and ‘Manny’ are of equal prominence / pitch)  Paired Sample T-Test  To see if the cross-over point occurs at a lower frequency in the plateau series

Prominence Experiment – Height Results  The cross-over point occurs at 190 Hz for the plateau series and Hz for the peak series  This difference is significant (p=0.000)

Prominence Experiment – Prominence Results  The cross-over point occurs at Hz for the plateau series and Hz for the peak series  This difference is significant (p=0.000)

Experiment Conclusions  The shape of the pitch contour does affect judgements of height and prominence  Perceived pitch is a close correlate of prominence  The function of the plateau may be to add to the prominence of the nuclear syllable

Sound Symbolism  The frequency code  smaller larynx = higher pitch  Deference, politeness > interrogativity  The production code  higher subglottal pressure = higher pitch  Higher accents at beginnings > initiality  The effort code  more effort = higher pitch  Larger excursions > emphasis / prominence

Substitute variables*  The physiological mechanism behind each code do not have to be created  Only the perceptual effect has to be created  For example, late peaks can be substituted for high peaks as they create the same perceptual effect Gussenhoven (2002)

Delayed peaks as substitute variable for pitch height  Production code (Wichmann et al. 1999)  Peaks are later in more initial accents  Effort code (Ladd and Morton 1997)  Peaks are later in more emphatic accents  Stimuli with later accents sound more emphatic  Frequency code (Gussenhoven and Chen 2000)  Peaks are later in questions in many languages  Stimuli with accents timed later sound more like questions

Plateaux as substitute variables  Plateaux occur in the same environments as peak delay:  In paragraph initial position (Wichmann et al. 1999) o Production code  In questions in Neapolitan Italian (D’Imperio 2002) o Frequency code

The nuclear plateau as a substitute variable  As the nuclear plateau’s effect is to increase perceived height and prominence…  …it may be a substitute variable for increased peak height  taking advantage of the effort code  Allowing speaker to increase the prominence of the nucleus  counteracting the effect of declination

Conclusions  The plateau is a substitute variable for peak height  Nuclear plateaux increase the perception of pitch height and prominence of the nucleus  Plateau allows the speaker to create this effect without having to step outside the physiologically determined slope of declination

References  D’Imperio, M (2002) “Language specific and universal constraints on tonal alignment: The nature of targets and “anchors”, in Bel, B, and I. Marlien (eds.) Proceedings of the Speech Prosody 2002 conference, Aix-en-Provence,  Gussenhoven, C. (2002) “Intonation and interpretation: Phonetics and phonology in Bel, B, and I. Marlien (eds.) Proceedings of the Speech Prosody 2002 conference, Aix-en- Provence,  Gussenhoven, C. and T. Rietveld, (1995) “ On the relation between pitch excursion size and prominence”, Journal of Phonetics, 13,  Gussenhoven, C. and A. Chen, (2000) “Universal and language specific effects in the perception of question intonation” Proc ICSLP, 6,  Knight (2002) “The influence of pitch span on intonational plateaux” in B. Bel and I. Marlien (eds.) Proceedings of the Speech Prosody 2002 conference, Aix-en-Provence,  Knight (2003) “Nuclear accent shape and the perception of syllable pitch”, Paper presented at LAGB, 16 April 2003  Ladd, D. and R. Morton, (1997) “The perception of intonational emphasis: continuous or categorical?” Journal of Phonetics, 25,  Terken, J. (1999) “Fundamental frequency and perceived prominence of accented syllables” JASA, 89, 4,  Wichmann, A, J. House and T. Rietveld (1999) “Discourse constraints on peak timing in English: Experimental evidence” Proc. XIVth ICPhS