Cross-linguistic filled pause realization: The acoustics of uh and um in native Dutch and non-native English

Abstract

It has been claimed that filled pauses are transferred from the first (L1) into the second language (L2), suggesting that they are not directly learned by L2 speakers. This would make them usable for cross-linguistic forensic speaker comparisons. However, under the alternative hypothesis that vowels in the L2 are learnable, L2 speakers adapt their pronunciation. This study investigated whether individuals remain consistent in their filled pause realization across languages, by comparing filled pauses (uh, um) in L1 Dutch and L2 English by 58 females. Next to the effect of language, effects of the filled pauses' position in the utterance were considered, as these are expected to affect acoustics and also relate to fluency. Mixed-effects models showed that, whereas duration and fundamental frequency remained similar across languages, vowel realization was language-dependent. Speakers used um relatively more often in English than Dutch, whereas previous research described speakers to be consistent in their um:uh ratio across languages. Results furthermore showed that filled-pause acoustics in the L1 and L2 depend on the position in the utterance. Because filled pause realization is partially adapted to the L2, their use as a feature for cross-linguistic forensic speaker comparisons may be restricted. V

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

“…Clark and Fox Tree (2002) found no systematic differences in numbers of occurrences in monologues relative to dialogues (p. 93, Table 2). In addition, we see no reason to assume that the acoustic realization of filled pauses will differ by discourse type, although their position in an utterance is likely to affect their acoustics (Swerts, 1998;de Boer and Heeren, 2020).…”

“…This assumption has been tested in prior work (de Boer and Heeren, 2020) among 58 speakers (a subset of whom is used in the current paper) speaking in their first language (L1) Dutch and second language (L2) English. A control experiment presented in this study showed that these languages both have uh and um with a vowel described as schwa, but it is realized with a 30-40-Hz higher first formant (F1), i.e., more open, by L1 English speakers than L1 Dutch speakers (see de Boer and Heeren, 2020). The sequential bilinguals from our dataset had somewhat higher F1 and lower second formants (F2) in their L2 English-filled pauses than in their L1 Dutch counterparts (de Boer and a) Author to whom correspondence should be addressed, ORCID: 0000-0003-0161-9115. b) ORCID: 0000-0001-7988-1346. c) ORCID: 0000-0001-7124-027X.…”

“…To test whether filled pauses are as consistent over time within speakers as is implied in the phonetic literature, we investigated in the current study filled pause realizations in speakers' L1 Dutch and L2 English in two noncontemporaneous recordings made >2.5 years apart. In a previous study, we analyzed filled pause acoustics across languages of 58 speakers in one moment in time (de Boer and Heeren, 2020). For the current study, we used recordings from a subset of 25 of the same speakers who had been recorded at two moments in time.…”

PRAAT scripts to measure speed fluency and breakdown fluency in speech automatically

“…This was produced in the speakers' L1, and if that was not English, also in their L2. L2 speakers are estimated to at least be at the B2 level (see De Boer & Heeren, 2020). For these recordings no fluency judgements were available.…”

“…Two annotators annotated the primary corpora. For the secondary corpus, data from the Dutch L1 speakers, in both languages, had already been annotated by at least two coders (see De Boer & Heeren, 2020). For the English L1 speakers in the secondary corpus, filled pauses were annotated by one coder (3 rd author).…”