Resources: SLRF 2026

Additional acoustic correlates:
visuals and data

Figure 1. Average vowel space size (in Hz) for /i/, /u/, and /ɑ/ across interlocutor conditions.

The prediction for vowel space size informed by the FDS literature would be that participants in both the NNS conditions would hyperarticulate their vowels more than when speaking to another NS; however, these results show the NNS-S condition had the smallest vowel space size, although these differences are not significant across conditions, as visualized in Figure 1.

NNS-R: mean = 83,512.86 Hz2 (reference level)
NS: mean = 75,222.81 Hz2 (β = -8268.54, p = 0.53)
NNS-S: mean = 73,940.56 Hz2 (β =-9545.79, p = 0.54)

Figure 2. Vowel dispersion (in Hz) from individual vowel centroids by participant, condition, and gender.

Figure 2. Articulation rate (phones per second) across conditions and by sentence position.

Articulation rate was not significantly different across conditions received. By design, the non-native speaker had a significantly slower articulation rate in the NNS-S condition compared to the NNS-R condition; comparatively, while articulation rate for participants was slower in the NNS-S condition (sentence non-finally), this difference was not statistically significant compared to the NNS-R condition. See the speech convergence section for more discussion.

NNS-R: mean = 13.11 phones per sec (reference level)
NS: mean = 13.12 phones per sec (β = 0.01, p = 0.98)
NNS-S: (mean = 12.99 phones per sec) (β = -0.35, p = 0.31)

Figure 3. Mean F0 (in Hz) across interlocutor conditions and by sentence position.

The mean F0 of participants was not significantly different between the NNS-R and NS conditions or the NNS-R and NNS-S conditions. This finding aligns with previous FDS work that commonly does not find significantly higher mean F0 when native speakers interact with non-native speakers (Kudera 2020, Dmitrieva et al. 2015).

NNS-R: mean = 164.23 Hz (reference level)
NS: mean = 159.60 Hz (β = 3.01, p = 0.40)
NNS-S: mean = 154.60 Hz (β = 2.44, p = 0.61)

Figure 4. F0 range (in Hz) across all interlocutor conditions and by sentence position.

The lack of significance for F0 range across conditions is generally supported by other studies on FDS. In the same way that Lorge & Katsos 2018 find that native speakers avoided hyperarticulation toward non-native speakers possibly as a way to avoid perceived offense, it is likely that an expanded F0 range would not be utilized between native and non-native speaking adults in a face-to-face information-swapping activity such as the map task, especially with the low-accented non-native confederate chosen for this study.

NNS-R: mean = 65.25 Hz (reference leve)
NS: mean = 60.31 Hz (β = 2.05, p = 0.84)
NNS-S: mean = 63.77 Hz (β = 1.45, p = 0.70)

Speech convergence: visuals and data

Significant acoustic correlates found for participants were vowel duration and hyperarticulation of /ɑ/. To confirm these results were observable measurements of FDS and not speech convergence, these same correlates were analyzed for the NNS confederate.

Figure 5. Vowel duration (in ms) across the non-native interlocutor conditions.

Vowel duration was significantly different between the non-native conditions, although this is not surprising as slower articulation rate (and likely related increased vowel duration) in the NNS-S condition was part of the experimental design.

NNS-R: mean = 87.87 ms (reference level)
NNS-S: mean = 104.96 ms (β = 18.99, p < 0.01)

Figure 6. Mean F1 and F2 for /ɑ/ across non-native interlocutor condition.

For all three vowels, /i/, /u/, and /ɑ/, neither mean F1 nor mean F2 were significantly different across conditions. While participants hyperarticulated /ɑ/, the NNS confederate did not.
F1: β =1.18, p = 0.98
F2: β = -33.57, p = 0.73

Arguments for convergence:
- significant increase in vowel duration for participants and the non-native confederate
- although, the latter result was by design as an effect of slower articulation rate that served as a possible FDS trigger tested by the study

Arguments against convergence:
- participants did not significantly slow their articulation rate when receiving the slow non-native articulation rate condition
- hyperarticulation of /ɑ/ for participants which did not appear in the non-native confederate data

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Past conference resources:

Resources for the International Conference on Language Documentation and Conservation 9

Iḷisaqativut

An online language learning resource for Northern Alaskan Iñupiaq with a phrasebook and word builder

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