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Figure 1.2 is a visual representation of an English sentence (“The museum hires musicians every evening”), which was generated from speech using an application called Praat (Boersma & Weenink, 2019). Depictions like this are of great use in phonetics research, and we will discuss them in more detail in later chapters. For now, it is enough to know that the top portion is an ACOUSTIC WAVEFORM capturing the oscillations of air particles when a speaker utters something into a microphone. The lower panel is a SPECTROGRAM illustrating the sound frequency components of speech, with lower frequencies at the bottom of the display. Dark regions in the spectrogram indicate concentrations of acoustic energy. Notice that the utterance appears as a variable acoustic pattern with occasional abrupt changes in darkness and shape. However, finding discreteness (as described earlier) in this representation turns out to be quite a challenge. In some instances, it is a straightforward matter to locate the beginning and end of a word, but in others it is much more difficult. Often, it is not possible to find clear demarcations between individual vowels and consonants within the words because these units overlap one another to varying degrees. What this means is that the phenomenon of discreteness is actually not an aspect of the acoustic signal itself. Rather, it is something that we humans partially impose upon the speech stream we hear. Put another way, discreteness is the result of the way we interpret vocally‐produced sound. This apparent lack of a one‐to‐one relationship between sound and perception adds an interesting layer of complexity to our understanding of the nature of speech—one that we will revisit throughout this book.

The APSSEL website provides a link to where you can download Praat and some instructions on getting started.

Figure 1.2 Acoustic waveform (top) and spectrogram (bottom) of “The museum hires musicians every evening,” as produced by an adult female speaker