Effects of obstruent voicing on vowel fundamental frequency in Dutch.

It has been known for a long time and a wide variety of languages that vowel fundamental frequency (F0) following voiceless obstruents tends to be significantly higher than F0 following voiced obstruents. There has been a long-standing debate about the cause of this phenomenon. Some evidence in previous work is more compatible with an articulatory account of this effect, while others support the auditory enhancement account. This paper investigates these consonant-related F0 perturbations in Dutch after initial fricatives (/v, f/) and stops (/b, p/), as compared to after the nasal /m/. Dutch is particularly interesting because it is a "true voicing" language, and because fricatives are currently undergoing a process of devoicing. Results show that F0 was raised after voiceless, but largely unaffected after voiced obstruents. Fricative voicing in /v/ and F0 level tend to covary: the less voicing in /v/, the higher F0 at onset. There was no trace of an active gesture to explicitly lower pitch after highly devoiced fricatives, as would be predicted by an auditory account. In conclusion, F0 perturbations after Dutch obstruents and their covariation patterns are taken as additional evidence to support an articulatory cause of consonant-related F0 effects.

Phonetic similarity of /s/ in native and second language: Individual differences in learning curves.

Second language learners may merge similar sounds from their native (L1) and second (L2) languages into a single phonetic category, neutralizing subphonemic differences in these similar sounds. This study investigates whether Dutch speakers produce phonetically distinct variants of /s/ in their L1 Dutch and L2 English, and whether and how this phonetic categorization develops over time. Target /s/ sounds in matching words in L1 and L2 were compared in their centre of spectral gravity. Speakers varied in their individual learning curves in the categorization of produced /s/ sounds, both in starting points and in longitudinal trajectories. After 3 years, however, all speakers had converged in producing their /s/ variants in L1 and L2 as two similar but different sounds.

Acoustic correlates of vowel intelligibility in clear and conversational speech for young normal-hearing and elderly hearing-impaired listeners.

The present investigation carried out acoustic analyses of vowels in clear and conversational speech produced by 41 talkers. Mixed-effects models were then deployed to examine relationships among acoustic and perceptual data for these vowels. Acoustic data include vowel duration, steady-state formant frequencies, and two measures of dynamic formant movement. Perceptual data consist of vowel intelligibility in noise for young normal-hearing and elderly hearing-impaired listeners, as reported by Ferguson in 2004 and 2012 [J. Acoust. Soc. Am. 116, 2365-2373 (2004); J. Speech Lang. Hear. Res. 55, 779-790 (2012)], respectively. Significant clear speech effects were observed for all acoustic metrics, although not all measures changed for all vowels and considerable talker variability was observed. Mixed-effects analyses revealed that the contribution of duration and steady-state formant information to vowel intelligibility differed for the two listener groups. This outcome is consistent with earlier research suggesting that hearing loss, and possibly aging, alters the way acoustic cues are used for identifying vowels.

Longitudinal trends in speech tempo: the case of Queen Beatrix.

Older talkers speak slower than young ones, but speech tempo has increased in the last decades. Have present-day older talkers slowed down with age or have they sped up with their community? This study investigates longitudinal patterns in articulation rate in formal speeches presented annually by Queen Beatrix between her ages 42 and 74. Her tempo decreased first and then increased in the last decade. Within a speech, acceleration and shortening increased longitudinally. These results suggest that this talker's preferred tempo has not decreased but increased longitudinally, presumably in accommodation to an increasing tempo in the Dutch language community.

The role of prosody in interpreting causality in English discourse.

Previous studies have well established that certain causal connectives encode information about the semantic-pragmatic distinction between different types of causal relations such as CAUSE-CONSEQUENCE versus CLAIM-ARGUMENT relations. These "specialized" causal connectives assist listeners in discerning different types of causality. Additionally, research has demonstrated that utterances expressing CLAIM-ARGUMENT relations exhibit distinct prosodic characteristics compared to utterances expressing CAUSE-CONSEQUENCE relations. However, it remains unknown whether the prosodic characteristics of utterances expressing causality can aid listeners in determining the specific type of causality being conveyed. To address this knowledge gap, this study investigates the impact of the prosody, specifically the prosody of the causal connective so in English, on listeners' interpretation of the type of causality expressed. We conducted a perception experiment employing a forced-choice discourse completion task, where the participants were required to select a continuation for each sound clip they heard. The sound clip consisted of factual events followed by the causal connective so. We found that the odds of listeners choosing subjective continuations over objective continuations increased when the connective so at the end of the sound clip was pronounced with subjective causality prosodic features, such as prolonged duration and a concave f0 contour. This finding suggests that the prosody of the connective so plays a role in conveying subjectivity in causality, guiding listeners in interpreting causal relations. In addition, it is important to note that our data revealed individual variation among listeners in their interpretations of prosodic information related to subjective-objective causality contrast.

Long-term within-speaker consistency of filled pauses in native and non-native speech.

Filled pauses are widely considered as a relatively consistent feature of an individual's speech. However, acoustic consistency has only been observed within single-session recordings. By comparing filled pauses in two recordings made >2.5 years apart, this study investigates within-speaker consistency of the vowels in the filled pauses uh and um, in both first language (L1) Dutch and second language (L2) English, produced by student speakers who are known to converge in other speech features. Results show that despite minor within-speaker differences between languages, the spectral characteristics of filled pauses in L1 and L2 remained stable over time.

Objective acoustic-phonetic speech analysis in patients treated for oral or oropharyngeal cancer.

OBJECTIVE: Speech impairment often occurs in patients after treatment for head and neck cancer. New treatment modalities such as surgical reconstruction or (chemo)radiation techniques aim at sparing anatomical structures that are correlated with speech and swallowing. In randomized trials investigating efficacy of various treatment modalities or speech rehabilitation, objective speech analysis techniques may add to improve speech outcome assessment. The goal of the present study is to investigate the role of objective acoustic-phonetic analyses in a multidimensional speech assessment protocol. PATIENTS AND METHODS: Speech recordings of 51 patients (6 months after reconstructive surgery and postoperative radiotherapy for oral or oropharyngeal cancer) and of 18 control speakers were subjectively evaluated regarding intelligibility, nasal resonance, articulation, and patient-reported speech outcome (speech subscale of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Head and Neck 35 module). Acoustic-phonetic analyses were performed to calculate formant values of the vowels /a, i, u/, vowel space, air pressure release of /k/ and spectral slope of /x/. RESULTS: Intelligibility, articulation, and nasal resonance were best predicted by vowel space and /k/. Within patients, /k/ and /x/ differentiated tumor site and stage. Various objective speech parameters were related to speech problems as reported by patients. CONCLUSION: Objective acoustic-phonetic analysis of speech of patients is feasible and contributes to further development of a speech assessment protocol.

Multilevel modeling of between-speaker and within-speaker variation in spontaneous speech tempo.

Speech tempo (articulation rate) varies both between and within speakers. The present study investigates several factors affecting tempo in a corpus of spoken Dutch, consisting of interviews with 160 high-school teachers. Speech tempo was observed for each phrase separately, and analyzed by means of multilevel modeling of the speaker's sex, age, country, and dialect region (between speakers) and length, sequential position of phrase, and autocorrelated tempo (within speakers). Results show that speech tempo in this corpus depends mainly on phrase length, due to anticipatory shortening, and on the speaker's country, with different speaking styles in The Netherlands (faster, less varied) and in Flanders (slower, more varied). Additional analyses showed that phrase length itself is shorter in The Netherlands than in Flanders, and decreases with speaker's age. Older speakers tend to vary their phrase length more (within speakers), perhaps due to their accumulated verbal proficiency.

Effects of timing regularity and metrical expectancy on spoken-word perception.

Certain types of speech, e.g. lists of words or numbers, are usually spoken with highly regular inter-stress timing. The main hypothesis of this study (derived from the Dynamic Attending Theory) is that listeners attend in particular to speech events at these regular time points. Better timing regularity should improve spoken-word perception. Previous studies have suggested only a weak effect of speech rhythm on spoken-word perception, but the timing of inter-stress intervals was not controlled in these studies. A phoneme monitoring experiment is reported, in which listeners heard lists of disyllabic words in which the timing of the stressed vowels was either regular (with equidistant inter-stress intervals) or irregular. In addition, metrical expectancy was controlled by varying the stress pattern of the target word, as either the same or the opposite of the stress pattern in its preceding words. Resulting reaction times show a main effect of timing regularity, but not of metrical expectancy. These results suggest that listeners employ attentional rhythms in spoken-word perception, and that regular speech timing improves speech communication.