The acoustics of Contemporary Standard Bulgarian vowels: A corpus study.

A comprehensive examination of the acoustics of Contemporary Standard Bulgarian vowels is lacking to date, and this article aims to fill that gap. Six acoustic variables-the first three formant frequencies, duration, mean f0, and mean intensity-of 11 615 vowel tokens from 140 speakers were analysed using linear mixed models, multivariate analysis of variance, and linear discriminant analysis. The vowel system, which comprises six phonemes in stressed position, [ε a ɔ i ɤ u], was examined from four angles. First, vowels in pretonic syllables were compared to other unstressed vowels, and no spectral or durational differences were found, contrary to an oft-repeated claim that pretonic vowels reduce less. Second, comparisons of stressed and unstressed vowels revealed significant differences in all six variables for the non-high vowels [ε a ɔ]. No spectral or durational differences were found in [i ɤ u], which disproves another received view that high vowels are lowered when unstressed. Third, non-high vowels were compared with their high counterparts; the height contrast was completely neutralized in unstressed [a-ɤ] and [ɔ-u] while [ε-i] remained distinct. Last, the acoustic correlates of vowel contrasts were examined, and it was demonstrated that only F1, F2 frequencies and duration were systematically employed in differentiating vowel phonemes.

The combined effects of contextual predictability and noise on the acoustic realisation of German syllables.

Speakers tend to speak clearly in noisy environments, while they tend to reserve effort by shortening word duration in predictable contexts. It is unclear how these two communicative demands are met. The current study investigates the acoustic realizations of syllables in predictable vs unpredictable contexts across different background noise levels. Thirty-eight German native speakers produced 60 CV syllables in two predictability contexts in three noise conditions (reference = quiet, 0 dB and -10 dB signal-to-noise ratio). Duration, intensity (average and range), F0 (median), and vowel formants of the target syllables were analysed. The presence of noise yielded significantly longer duration, higher average intensity, larger intensity range, and higher F0. Noise levels affected intensity (average and range) and F0. Low predictability syllables exhibited longer duration and larger intensity range. However, no interaction was found between noise and predictability. This suggests that noise-related modifications might be independent of predictability-related changes, with implications for including channel-based and message-based formulations in speech production.

Local and Global Cues in the Prosodic Realization of Broad and Narrow Focus in Bulgarian.

In this study, local and global prosodic cues for information structure are examined in the elicited production of six Bulgarian sentences. The sentences were produced in response to different questions, devised to prompt different focus realizations (broad focus and non-contrastive and contrastive narrow focus). Results show that speakers consistently differentiate broad and narrow focus by means of both local and global acoustic cues, by producing different pitch accent types on the nuclear syllable and reducing the 'phonetic strength' of the default pre-nuclear accent in the narrow focus condition. Thus, the difference between the acoustic properties of the nuclear and the pre-nuclear accented syllables is smaller in the broad focus condition and greater in the narrow focus condition. Contrastive and non-contrastive narrow-focus accents are differentiated by local cues, i.e., by longer duration when the focus is early in the sentence and by global cues, i.e., by enhancing the tonal contrast between the nuclear prominence of CW2 and the pre-nuclear prominence of CW1 when the focus is late in the sentence.

Do rhythm measures reflect perceived rhythm?

In a production study, Bulgarian, English and German verses with regular poetic metrical metres of different types and elicited prose utterances with varied accentual patterns are produced in textual and iterative (dada) form and measured at syllable level according to the pairwise variability index (PVI) principle. Systematic differences in PVI values show that the measure is sensitive to metrical differences. But variations for utterances with the same metrical structure and comparable measures for accentually different utterances show the measure to be insensitive to the temporal distribution of accents. A perceptual experiment with Bulgarian, English and German subjects confirms the hypothesis that the perceived strength of rhythmicity in a line of verse is determined not only by its temporal structure, but also by other acoustic properties, most clearly by F(0) change within the metrical foot.