# Exploring the Age Effects on European Portuguese Vowel Production: An Ultrasound Study
## 5 Conclusions  
In this study, the age-related articulatory changes are investigated through the analysis of the US tongue contours of nine EP oral vowels produced by 10 female speakers aged between 23 and 73. Advancing our preliminary work on this topic, an improved automatic method for tongue contour tracing allowed expanding the number of considered speakers and supported a novel normalization procedure for inter-speaker comparison.  
In light of this new articulatory data, it can be concluded that the tongue tends to be higher and more advanced with aging for almost all vowels, meaning that the vowel articulatory space tends to be higher, advanced, and bigger in older females. Concerning the context, the vowel space tends to be more advanced for isolated vowels comparing with vowels produced in disyllabic sequences for older females, while younger females tend to present a sharp reduction in the articulatory vowel space in disyllabic sequences.  
These results contribute to an accurate articulatory description of EP oral vowels, and they also provide valuable insights about the vowel articulatory normal patterns of aging among female Portuguese adults. As this study provides information from adults who speak a language different from English, it might help to better understand cross-linguistic similarities and language-particular features of vowel aging. Furthermore, these data are important as a reference for the clinical assessment and treatment of different speech disorders, which are often age-related, and to provide articulatory information for speech synthesis based on production models.  
In the long term, the systematic approach enabled by the adopted automatic method of tongue contour tracing, along with the normalization supporting inter-speaker comparison, may open the way toward broader lifespan articulatory studies and the development of larger databases with speakers from infancy to old age.  
**Author Contributions:** Conceptualization, L.A., A.R.V., C.O. and A.T.; methodology, L.A., A.R.V., F.B., A.T., S.S., P.M. and C.O.; validation, L.A., A.R.V., F.B., A.T., C.O. and S.S.; formal analysis, L.A., A.R.V., F.B. and A.T.; investigation, L.A. and A.R.V.; software, L.A., F.B. and A.T.; data curation, L.A., F.B. and A.T.; writing--original draft preparation, L.A. and A.R.V.; writing--review and editing, F.B., A.T., S.S., P.M. and C.O.; visualization, L.A. and F.B.; supervision, A.T., S.S. and C.O.; project administration, A.T., S.S. and C.O.; funding acquisition, L.A., A.T., S.S. and C.O. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was financially supported by the projects VoxSenes (POCI-01-0145-FEDER-03082) and MEMON (POCI-01-0145-FEDER-028976)--COMPETE2020 under POCI and FEDER, and by national funds (OE), through FCT/MCTES--, SOCA--Smart Open Campus CENTRO-01-0145-FEDER-000010 (Portugal 2020 under POCI and FEDER) and by IETA Research Unit funding (UIDB/00127/2020). The first author was funded by the grants SFRH/BD/115381/2016 and COVID/BD/151744/2021 (funded by FCT, through FSE and by CENTRO2020).  
**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki and approved by by the Ethics Committee of Escola Superior de Enfermagem de Coimbra, Portugal (approval number 639/12-2019).  
**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.  
**Acknowledgments:** We are very grateful to all the adults who contributed as speakers.  
**Conflicts of Interest:** The authors declare no conflict of interest.  
Appendix A TA and TH Scaled Measures Obtained of All Tongue Contours without Any Manual Verification