The Greennn Tree — Lengthening Position Influences Uncertainty Perception

Abstract

Synthetic speech can be used to express uncertainty in dialogue systems by means of hesitation. If a phrase like "Next to the green tree" is uttered in a hesitant way, that is, containing lengthening, silences, and fillers, the listener can infer that the speaker is not certain about the concepts referred to. However, we do not know anything about the referential domain of the uncertainty; if only a particular word in this sentence would be uttered hesitantly, e.g. "the greee:n tree", the listener could infer that the uncertainty refers to the color in the statement, but not to the object. In this study, we show that the domain of the uncertainty is controllable. We conducted an experiment in which color words in sentences like "search for the green tree" were lengthened in two different positions: word onsets or final consonants, and participants were asked to rate the uncertainty regarding color and object. The results show that initial lengthening is predominantly associated with uncertainty about the word itself, whereas final lengthening is primarily associated with the following object. These findings enable dialogue system developers to finely control the attitudinal display of uncertainty, adding nuances beyond the lexical content to message delivery.

Cognitive Load Increases Spoken and Gestural Hesitation Frequency

“…In this sense, lengthening can be regarded as pausing within the execution of the articulatory plan, but with ongoing phonation (Eklund 2004). Such lengthening is interpreted by listeners as hesitation, the extra time so generated is used by listeners just like other hesitations (Betz et al 2018), and it serves pragmatic functions such as the expression of epistemic states like uncertainty (Betz et al 2019). Lengthening shares many characteristics of pauses and fillers, and they are a very frequent and unobtrusive hesitation signal (cf., Betz (2020) for an overview), for which reasons they are treated as pause manifestations in this study alongside fillers and silences.…”

Perception of prosodic variation for speech synthesis using an unsupervised discrete representation of F0

“…For example, previous work has identified consistent variations in prosody with respect to structural elements in the discourse context [2,3,4] and sentence level information structure [5,6]. Variation has also been identified with respect to specific speaker attitudes [7,8,9] and stances [10,11,12].…”

“…-insulted, upset, rhetorical, sad 19 "I'm sorry." -fake apology, passive aggressive, question, apology, "standard" style, upset 9 He wanted a turnip. -statement, narrative, continuation rise, sad, bored 7 They both tugged and tugged.…”