Acoustic analysis, once a method used primarily within the domain of phonetics, has become an increasingly necessary skill across the field of linguistics. To name just a few examples, phonologists sometimes appeal to acoustic data to substantiate theoretical arguments, sociolinguists tend to characterize vowel shifts and mergers in terms of their acoustic properties, and psycholinguists frequently draw on acoustic analysis techniques to construct stimuli for experiments.
The analysis of acoustic signals is mainly performed with the help of generally available software. Because of its capability of creating publication-quality graphics, the pictures in this chapter were made with Praat (Boersma and Weenink 1992–2012), a general set of tools for analyzing, synthesizing and manipulating speech and other sounds, bundled into a single integrated computer program. Praat is available free of charge for all current major computer platforms (nowadays MacOS, Windows, Linux) and is continually updated to accommodate new operating system developments and new analysis methods.
Graphical software allows us to perform acoustic analysis by inspecting visualized speech. The types of visualization addressed in the present chapter are the waveform, the pitch curve, the intensity curve, the spectrum, the spectrogram, and formant tracks. These types of visualization will be seen to help in measuring the following articulatory, acoustic, and auditory quantities: glottal period, resonance frequencies, pitch, duration, intensity, noisiness, and place of articulation. Examples of practical uses for each of these measures will appear throughout the chapter.