1. Audacity Team. (2019). Audacity: Free, open source, cross-platform audio software for multi-track recording and editing. (2.2.1) [Computer software]. https://www.audacityteam.org/
2. Fitting Linear Mixed-Effects Models Using lme4;Bates, D.Mächler, M.Bolker, B.Walker, S.;Journal of Statistical Software,2015
3. Berinstein, A. E. (1979). A Cross-linguistic Study on the Perception and Production of Stress (MA Thesis, Unviersity of California). https://escholarship.org/uc/item/0t0699hc#author
4. Boersma, P., & Weenink, D. (2019). Praat: Doing Phonetics by Computer (6.0.56) [Computer software]. http://www.praat.org/
5. The declination effect;Breckenridge, J;The Journal of the Acoustical Society of America,1977