Visualising speech rhythm: A survey of alternatives Tommi Nieminen, Michael L. O’Dell Abstract One of the requirements in of speech rhythm research is to be able to visualise the rhythm, or the difference between given speech rhythms. This is especially important for didactic pur- poses. We give here a brief survey of the different visualisation models available and study their capabilities and limitations, and also experiment with our own model, the “bubble chart” visualisation. 1. What is rhythm to a linguist? Rhythm is one of the prosodic features of speech. Its importance for fluent, na- tive-like speech cannot be overstressed. But how can the rhythm of speech be conveyed to a linguist or a naive learner, especially in the (sometimes inevita- ble) absence of speech sound? Visualisation is here conceived of as the means to do that. The search for the “perfect” visualisation technique may also provide valuable insight in the very nature of speech rhythm: what it is and what it is not. In effect, graphical visualisation of rhythm may be thought of standing in the same relation to the study of speech rhythm as spectrograms have stood for the study of speech generally. Visualisation is only a method, but as such, it can provide weighty support for the research. Rhythm has been defined in many ways in the phonetic literature. In the simplest formulations, rhythm is “the structure of intervals in a succession of events” (Allen, 1972: 72) or even just “the structure of a sequence” (Allen & Hawkins, 1979: 227). By design this kind of description is not limited to the rhythm of speech, and for that very reason it is not of great aid to the phoneti- cian in need of a methodological working definition. More speech-oriented is Wagner’s (2010) definition of rhythm as “a sequence of fundamental rhythmical events […] which are characterised by their prominence structure, e.g. a (more or less regular) order of stronger and weaker beats perceived as groups”. This definition highlights the important characteristics of speech rhythm: repetition (of some unit or units of speech), alternation (of two or more different kinds of units), structure (created by the units and their alternation patterns), and group- ing (how, in addition to what is meant by structure, the units cluster around each other). These are the features a workable rhythmic visualisation should be able to represent. Methodologically speaking, speech rhythm was for decades nearly synony- mous with “isochrony” ever since Pike (1945). Isochrony means that for some