Acoustics of Breath Noises in Human Speech: Descriptive and Three-Dimensional Modeling Approaches.

PURPOSE: Breathing is ubiquitous in speech production, crucial for structuring speech, and a potential diagnostic indicator for respiratory diseases. However, the acoustic characteristics of speech breathing remain underresearched. This work aims to characterize the spectral properties of human inhalation noises in a large speaker sample and explore their potential similarities with speech sounds. Speech sounds are mostly realized with egressive airflow. To account for this, we investigated the effect of airflow direction (inhalation vs. exhalation) on acoustic properties of certain vocal tract (VT) configurations. METHOD: To characterize human inhalation, we describe spectra of breath noises produced by human speakers from two data sets comprising 34 female and 100 male participants. To investigate the effect of airflow direction, three-dimensional-printed VT models of a male and a female speaker with static VT configurations of four vowels and four fricatives were used. An airstream was directed through these VT configurations in both directions, and their spectral consequences were analyzed. RESULTS: For human inhalations, we found spectra with a decreasing slope and several weak peaks below 3 kHz. These peaks show moderate (female) to strong (male) overlap with resonances found for participants inhaling with a VT configuration of a central vowel. Results for the VT models suggest that airflow direction is crucial for spectral properties of sibilants, /ç/, and /i:/, but not the other sounds we investigated. Inhalation noise is most similar to /ə/ where airflow direction does not play a role. CONCLUSIONS: Inhalation is realized on ingressive airflow, and inhalation noises have specific resonance properties that are most similar to /ə/ but occur without phonation. Airflow direction does not play a role in this specific VT configuration, but subglottal resonances may do. For future work, we suggest investigating the articulation of speech breathing and link it to current work on pause postures. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.24520585.

Phonetic Cues in Auditory Identification of Bulgarian, Czech, Polish, and Russian Language of Origin.

This work presents the results of an auditory language of origin identification experiment. Disyllabic and trisyllabic logatomes were recorded by speakers of Bulgarian, Czech, Polish, and Russian, and presented to L1 speakers of the abovementioned Slavic languages. The goals of the test were to verify the ability of lay listeners to recognize the linguistic origin of speakers, based on spoken samples with limited segmental and suprasegmental information, and to correlate the signal features with the subjects' performance. It was found that position of word stress is not an important predictor in language recognition. However, inherent vowel characteristics such as duration and vowel space computed by the means of Pillai scores correlate with subjects' performance. Both the linguistic profile and the familiarity with closely related languages also appear to be relevant predictors of listeners' performance. Finally, the information-theoretic notion of surprisal applied on regular cross-linguistic sound correspondences was correlated with recognition scores; though, the correlations did not reach the threshold of statistical significance. We conclude that auditory identification of linguistic origin by lay persons, native speakers of closely related languages, is possible even when exposed to limited segmental information, which can serve as a cue in the identification of linguistic origin.

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.

Phonetic detail in German syllable pronunciation: influences of prosody and grammar.

This study presents two experiments designed to disentangle various influences on syllable pronunciation. Target syllables were embedded in carrier sentences, read aloud by native German participants, and analyzed in terms of syllable and vowel duration, acoustic prominence, and spectral similarity. Both experiments revealed a complex interaction of different factors, as participants attempted to disambiguate semantically and syntactically ambiguous structures while at the same time distinguishing between important and unimportant information. The first experiment examined German verb prefixes that formed prosodic minimal pairs. Carrier sentences were formulated so as to systematically vary word stress, sentence focus, and the type of syntactic boundary following the prefix. We found clear effects of word stress on duration, prominence, and spectral similarity as well as a small influence of sentence focus on prominence levels of lexically stressed prefixes. While sentence boundaries were marked by particularly high prominence and duration values, hardly any effect was shown for word boundaries. The second experiment compared German function words which were segmentally identical but appeared in different grammatical roles. Here, definite articles were found to be shorter than relative pronouns and still shorter than demonstrative pronouns. As definite articles are also much more common than the other two lexical classes, effects of lemma frequency might also have played a role.

Vowel- and text-based cepstral analysis of chronic hoarseness.

OBJECTIVES/HYPOTHESIS: Automatic voice evaluation is usually performed on stable sections of sustained vowels, which often cannot capture hoarseness properly. The measures cepstral peak prominence (CPP) and smoothed CPP (CPPS) do not require exact determination of the cycles of fundamental frequency like established perturbation-based measures. They can also be applied to text recordings. In this study, they were compared with perceptual evaluation of voice quality and the German roughness-breathiness-hoarseness (RBH) scheme. STUDY DESIGN: Retrospective data analysis. METHODS: Seventy-three hoarse patients (48.3±16.8 years) uttered the vowel /e/ and read the German version of the text "The North Wind and the Sun". The text recordings were evaluated perceptually by five speech therapists and physicians according to the RBH scale. The criterion "overall quality" was measured on a 4-point scale and a visual analog scale. For the human-machine correlation, the automatic measures of the Praat program (vowels only) and the "cpps" software were compared with the experts' ratings. The experiments were repeated for speakers with jitter ≤5% or shimmer ≤5% (n=47). RESULTS: For the entire group (n=73), the best human-machine results for most of the rating criteria were obtained for text-based CPP and CPPS (up to |ρ|=0.73). For the 47 selected speakers, the correlation was remarkably worse for all measures but still best for text-based CPP and CPPS (|ρ|≤0.50). CONCLUSIONS: Cepstrum analysis should be performed on a text recording. Then, it outperforms all perturbation-based measures, and it can be a meaningful objective support for perceptual analysis.

Multilevel exemplar theory.

This paper presents recent research that provides an overarching model of exemplar theory capable of explaining phenomena across the phonetic and syntactic strata. The model represents a unique exemplar-based account of constituency interactions encompassing both linguistic domains. It yields simulation and experimental results in keeping with experimental findings in the literature on syllable duration variability and offers an exemplar-theoretic account of local grammaticality. In addition, it provides some insights into the nature of exemplar cloud formation and demonstrates experimentally the potential gains that can be enjoyed via the use of rich exemplar representations.