Vowel Acoustics of Nungon Child-Directed Speech, Adult Dyadic Conversation, and Foreigner-Directed Monologues

Project description:
In many communities around the world, speech to infants (IDS) and small children (CDS) has increased mean pitch, increased pitch range, increased vowel duration, and vowel hyper-articulation when compared to speech directed to adults (ADS). Some of these IDS and CDS features are also attested in foreigner-directed speech (FDS), which has been studied for a smaller range of languages, generally major national languages, spoken by millions of people. We examined vowel acoustics in CDS, conversational ADS, and monologues directed to a foreigner (possible FDS, labeled MONO here) in the Towet dialect of the Papuan language Nungon, spoken by 300 people in a remote region in northeastern Papua New Guinea. Previous work established that Nungon CDS entails optional use of consonant alteration, special nursery vocabulary, and special morphosyntax. This study shows that Nungon CDS to children aged 2;2–3;10 lacks vowel hyper-articulation, but still displays other common prosodic traits of CDS styles around the world: increased mean pitch and pitch range. A developmental effect was also attested, in that speech to 2-year-olds contained vowels that were significantly longer than those in speech to 3-year-olds, which in turn had vowels of similar duration to those in Nungon ADS. We also found that Nungon FDS vowel triangles, measured from monologues primarily directed to a non-native speaker, were significantly larger than those of either CDS or conversational ADS, indicating vowel hyper-articulation. The Nungon pattern may align with the patterns of vowels in Norwegian IDS, CDS, and FDS, where hyper-articulation is found in FDS, but not CDS or IDS. The languages of the New Guinea area constitute 20% of the world's languages, but neither an acoustic comparison of vowels in CDS and ADS, nor an acoustic study of FDS, has previously been completed for any language of New Guinea. The function of an FDS style in a small, closed community like those of much of New Guinea may differ from that in larger societies, since there are very few non-native speakers of Nungon. Thus, this study uses monologues recorded with a foreign researcher as interlocutor to study Nungon FDS.

Dataset:
Acoustic Data from Child-Directed Speech, Adult Dyadic Conversation, and Monologues directed at a non-native speaker, in the Papuan language Nungon
Vowel hyper-articulation, usually identified from the size of the triangle formed from the corner vowels /i/, /a/, and /u/, often features in clearly articulated speech styles. It has been attested in infant-directed speech (IDS) and child-directed speech (CDS), reading-out-loud styles, and foreigner-directed speech (FDS), in numerous communities. It is as yet unclear whether reading out loud and FDS universally feature hyper articulation of vowels, but vowel hyper-articulation in IDS and CDS is decidedly not universal. Studies of Cantonese, Dutch, German, Japanese, and Norwegian IDS have shown that the IDS vowel space in these languages is either similar in area to that of adult-directed speech (ADS), or that the IDS vowel space has reduced area relative to the ADS vowel space, hence showing hypo-articulation. We examined vowel acoustics in CDS and conversational ADS in the Papuan language Nungon, spoken by 1,000 people in a remote region in NE Papua New Guinea. Previous work established that Nungon CDS entails optional use of consonant alteration, special nursery vocabulary, and special morphosyntax, but acoustics and prosody were untested. This study shows that Nungon CDS to children aged 2;2–3;10 lacks any indication of vowel hyper-articulation. But Nungon CDS still displays other common prosodic traits of CDS styles around the world: increased mean pitch, and increased pitch range. Vowels in Nungon CDS to two-year-olds differed acoustically from those in CDS to three-year-olds only in duration, with vowels in CDS to the younger group lasting significantly longer than those in CDS to the older group, which had similar duration to ADS vowels. Finally, we compared the acoustics of vowels in Nungon CDS and conversational ADS to vowels in monologue narratives that were produced with a non-native Nungon speaker as primary listener, hence can be considered FDS. The vowel triangles of the Nungon FDS monologues were significantly larger than those of either CDS or conversational ADS, indicating vowel hyper-articulation. Mean pitch and pitch range in FDS monologues, compared with CDS and conversational ADS, differed among women and men, possibly relating to cultural expectations of female and male storytelling and conversational styles.

The dataset is available at osf identifier 6pr8s/.
To discuss the data contact Hannah Sarvasy ORCID 0000-0002-9551-480X.

项目描述：
在全球许多社区中，与面向成人的言语（Adult-Directed Speech, ADS）相比，婴儿指向语（Infant-Directed Speech, IDS）和儿童指向语（Child-Directed Speech, CDS）具有平均音高升高、音高范围扩大、元音时长增加及元音过度清晰化等特征。这些IDS和CDS的部分特征也见于外国人指向语（Foreigner-Directed Speech, FDS），但FDS的研究仅覆盖少数由数百万人使用的主要国家语言。本研究考察了巴布亚语言Nungon的Towet方言中，儿童指向语（CDS）、会话式成人指向语（ADS）及面向外国人的独白（可能为FDS，本文标记为MONO）的元音声学特征。先前研究已证实Nungon的CDS包含辅音变体的可选使用、特殊 nursery词汇及特殊形态句法，但尚未涉及声学与韵律特征。本研究发现，面向2岁2个月至3岁10个月儿童的Nungon CDS缺乏元音过度清晰化，但仍具备全球CDS风格常见的其他韵律特征：平均音高升高及音高范围扩大。此外，研究还发现发展性效应：面向2岁儿童的言语中元音时长显著长于面向3岁儿童的言语，而后者元音时长与ADS相近。我们还发现，面向非母语者的Nungon独白（FDS）元音三角形（由 corner元音/i/、/a/、/u/构成）显著大于CDS和会话ADS，表明存在元音过度清晰化。新几内亚地区的语言占世界语言总数的20%，但此前尚未对该地区任何语言完成CDS与ADS的元音声学比较，亦未开展FDS的声学研究。在如新几内亚多数小型封闭社区中，FDS的功能可能与大型社会不同，因Nungon的非母语使用者极少。因此，本研究采用与外国研究者对话录制的独白来探究Nungon的FDS。

数据集：
巴布亚语言Nungon中儿童指向语、成人对话及面向非母语者独白的声学数据
元音过度清晰化通常通过 corner元音/i/、/a/、/u/构成的三角形大小识别，常见于清晰表达的言语风格中。它已在众多社区的婴儿指向语（IDS）、儿童指向语（CDS）、朗读风格及外国人指向语（FDS）中得到证实。目前尚不清楚朗读与FDS是否普遍存在元音过度清晰化，但IDS与CDS中的元音过度清晰化显然并非普遍现象。对粤语、荷兰语、德语、日语及挪威语IDS的研究表明，这些语言的IDS元音空间面积要么与成人指向语（ADS）相近，要么相对ADS有所缩小（即呈现元音欠清晰化）。本研究考察了巴布亚语言Nungon中CDS与会话ADS的元音声学特征，该语言由新几内亚东北部偏远地区的1000人使用。先前研究已证实Nungon的CDS包含辅音变体的可选使用、特殊 nursery词汇及特殊形态句法，但声学与韵律特征尚未被测试。本研究发现，面向2岁2个月至3岁10个月儿童的Nungon CDS无任何元音过度清晰化迹象，但仍具备全球CDS风格常见的其他韵律特征：平均音高升高及音高范围扩大。面向2岁儿童的Nungon CDS元音与面向3岁儿童的CDS元音仅在时长上存在声学差异——前者元音时长显著长于后者，而后者元音时长与ADS相近。最后，我们将Nungon CDS与会话ADS的元音声学特征与面向非母语者（因此可视为FDS）的独白叙事元音进行比较，发现Nungon FDS独白的元音三角形显著大于CDS与会话ADS，表明存在元音过度清晰化。与CDS与会话ADS相比，FDS独白的平均音高及音高范围在男女间存在差异，这可能与女性及男性叙事和会话风格的文化预期相关。

数据集可通过osf标识符6pr8s/获取。
如需讨论数据，请联系Hannah Sarvasy（ORCID 0000-0002-9551-480X）。