In linguistics, the study of acoustics refers to the study of the physical properties of a speech signal. This includes the frequency (pitch), intensity (loudness), and duration (length of articulation) of phonemes, words, or utterances (Source). Research in phonetics is done through the use of technology such as spectrograms and waveforms.
Skwxwú7mesh: Watt et al. (2000) investigate the acoustic properties of stress such as pitch, duration, and amplitude (loudness) which are affected by stress patterns in Skwxwú7mesh. Particularly, they look at these effects on the vowels /a/ and /u/. The paper concludes that the acoustic properties such as pitch, duration, and amplitude are in fact relevant when perceiving primary stress in Skwxwú7mesh.
Find this study here