Thinking probabilistically in the study of intonational speech prosody.

Speech prosody, the melodic and rhythmic properties of a language, plays a critical role in our everyday communication. Researchers have identified unique patterns of prosody that segment words and phrases, highlight focal elements in a sentence, and convey holistic meanings and speech acts that interact with the information shared in context. The mapping between the sound and meaning represented in prosody is suggested to be probabilistic-the same physical instance of sounds can support multiple meanings across talkers and contexts while the same meaning can be encoded in physically distinct sound patterns (e.g., pitch movements). The current overview presents an analysis framework for probing the nature of this probabilistic relationship. Illustrated by examples from the literature and a dataset of German focus marking, we discuss the production variability within and across talkers and consider challenges that this variability imposes on the comprehension system. A better understanding of these challenges, we argue, will illuminate how the human perceptual, cognitive, and computational mechanisms may navigate the variability to arrive at a coherent understanding of speech prosody. The current paper is intended to be an introduction for those who are interested in thinking probabilistically about the sound-meaning mapping in prosody. Open questions for future research are discussed with proposals for examining prosodic production and comprehension within a comprehensive, mathematically-motivated framework of probabilistic inference under uncertainty. This article is categorized under: Linguistics > Language in Mind and Brain Psychology > Language.

Listeners' adaptation to unreliable intonation is speaker-sensitive.

Variable linguistic environments require the ability to quickly update expectations and behavior including speech comprehension. This adaptive capacity is key to understanding how listeners successfully recognize speaker intentions in light of the ubiquitous variability in speech. The present study investigates how listeners' real-time sentence comprehension adapts to speaker-specific prosodic variability. In two forced choice mouse tracking experiments, listeners had to identify a visual referent guided by pre-recorded instructions. When exposed to a speaker that uses unconventional pitch accent placement, listeners discard intonational information for that speaker, but keep using intonation to resolve the referential ambiguity for another speaker that places pitch accents conventionally. These results show for the first time that intonationally guided sentence comprehension adapts in a speaker-sensitive way. The study further provides valuable first insights into the temporal unfolding of this adaptation process. Listeners first attribute unconventional patterns to the context, thus discarding the informational value of intonation for both speakers. After sufficient evidence, however, listeners start attributing unexpected patterns to only the unconventional speaker. Materials, data, and scripts can be retrieved here: http://osf.io/fdpg4.

Evidential Strength of Intonational Cues and Rational Adaptation to (Un-)Reliable Intonation.

Intonation plays an integral role in comprehending spoken language. Listeners can rapidly integrate intonational information to predictively map a given pitch accent onto the speaker's likely referential intentions. We use mouse tracking to investigate two questions: (a) how listeners draw predictive inferences based on information from intonation? and (b) how listeners adapt their online interpretation of intonational cues when these are reliable or unreliable? We formulate a novel Bayesian model of rational predictive cue integration and explore predictions derived under a concrete linking hypothesis relating a quantitative notion of evidential strength of a cue to the moment in time, relative to the unfolding speech signal, at which mouse trajectories turn towards the eventually selected option. In order to capture rational belief updates after concrete observations of a speaker's behavior, we formulate and explore an extension of this model that includes the listener's hierarchical beliefs about the speaker's likely production behavior. Our results are compatible with the assumption that listeners rapidly and rationally integrate all available intonational information, that they expect reliable intonational information initially, and that they adapt these initial expectations gradually during exposition to unreliable input. All materials, data, and scripts can be retrieved here: https://osf.io/dnbuk/.

Word final schwa is driven by intonation-The case of Bari Italian.

In order to convey pragmatic functions, a speaker has to select an intonation contour (the tune) in addition to the words that are to be spoken (the text). The tune and text are assumed to be independent of each other, such that any one intonation contour can be produced on different phrases, regardless of the number and nature of the segments they are made up of. However, if the segmental string is too short, certain tunes-especially those with a rising component-call for adjustments to the text. In Italian, for instance, loan words such as "chat" can be produced with a word final schwa when this word occurs at the end of a question. This paper investigates this word final schwa in the Bari variety in a number of different intonation contours. Although its presence and duration is to some extent dependent on idiosyncratic properties of speakers and words, schwa is largely conditioned by intonation. Schwa cannot thus be considered a mere phonetic artefact, since it is relevant for phonology, in that it facilitates the production of communicatively relevant intonation contours.

The effects of Thalamic Deep Brain Stimulation on speech dynamics in patients with Essential Tremor: An articulographic study.

Acoustic studies have revealed that patients with Essential Tremor treated with thalamic Deep Brain Stimulation (DBS) may suffer from speech deterioration in terms of imprecise oral articulation and reduced voicing control. Based on the acoustic signal one cannot infer, however, whether this deterioration is due to a general slowing down of the speech motor system (e.g., a target undershoot of a desired articulatory goal resulting from being too slow) or disturbed coordination (e.g., a target undershoot caused by problems with the relative phasing of articulatory movements). To elucidate this issue further, we here investigated both acoustics and articulatory patterns of the labial and lingual system using Electromagnetic Articulography (EMA) in twelve Essential Tremor patients treated with thalamic DBS and twelve age- and sex-matched controls. By comparing patients with activated (DBS-ON) and inactivated stimulation (DBS-OFF) with control speakers, we show that critical changes in speech dynamics occur on two levels: With inactivated stimulation (DBS-OFF), patients showed coordination problems of the labial and lingual system in terms of articulatory imprecision and slowness. These effects of articulatory discoordination worsened under activated stimulation, accompanied by an additional overall slowing down of the speech motor system. This leads to a poor performance of syllables on the acoustic surface, reflecting an aggravation either of pre-existing cerebellar deficits and/or the affection of the upper motor fibers of the internal capsule.

Grammatical number elicits SNARC and MARC effects as a function of task demands.

Despite the robustness of the spatial-numerical association of response codes (SNARC) and linguistic markedness of response codes (MARC) effect, the mechanisms that underlie these effects are still under debate. In this paper, we investigate the extraction of quantity information from German number words and nouns inflected for singular and plural using two alternative forced choice paradigms. These paradigms are applied to different tasks to investigate how access to quantity representation is modulated by task demands. In Experiment 1, we replicated previous SNARC findings for number words-that is, a relative left-hand advantage for words denoting small numbers and a right-hand advantage for words denoting large numbers in semantic tasks (parity decision and quantity comparison). No SNARC effect was obtained for surface or lexical processing tasks (font categorization and lexical decision). In Experiment 2, we found that German words inflected for singular had a relative left-hand advantage, and German words inflected for plural a relative right-hand advantage, showing a SNARC-like effect for grammatical number. The effect interfered, however, with a MARC-like effect based on the markedness asymmetry of singulars and plurals. These two effects appear to be dissociated by response latency rather than task demands, with MARC being more pronounced in early responses and SNARC being more pronounced in late responses. The present findings shed light on the relationship of conceptual number and grammatical number and constrain current accounts of the SNARC and MARC effects.

The effect of deep brain stimulation on the speech motor system.

PURPOSE: Chronic deep brain stimulation of the nucleus ventralis intermedius is an effective treatment for individuals with medication-resistant essential tremor. However, these individuals report that stimulation has a deleterious effect on their speech. The present study investigates one important factor leading to these effects: the coordination of oral and glottal articulation. METHOD: Sixteen native-speaking German adults with essential tremor, between 26 and 86 years old, with and without chronic deep brain stimulation of the nucleus ventralis intermedius and 12 healthy, age-matched subjects were recorded performing a fast syllable repetition task (/papapa/, /tatata/, /kakaka/). Syllable duration and voicing-to-syllable ratio as well as parameters related directly to consonant production, voicing during constriction, and frication during constriction were measured. RESULTS: Voicing during constriction was greater in subjects with essential tremor than in controls, indicating a perseveration of voicing into the voiceless consonant. Stimulation led to fewer voiceless intervals (voicing-to-syllable ratio), indicating a reduced degree of glottal abduction during the entire syllable cycle. Stimulation also induced incomplete oral closures (frication during constriction), indicating imprecise oral articulation. CONCLUSION: The detrimental effect of stimulation on the speech motor system can be quantified using acoustic measures at the subsyllabic level.