Research on speech rhythm has been notoriously oblivious to describing actual rhythms in speech. We present here a model of speech rhythm at the sentence level inspired by musical conceptions of meter. We posit that speech is underlain by a basic metricality. However, instead of arguing that speech is isochronous, we propose that utterances can have internal changes of meter, making them “heterometric.” In addition, we see 2 rhythmic devices for obviating the need for meter changes within utterances and thus maintaining the stability of the rhythm. Both of them involve subdivisions of component beats into subbeats: 1) subdivisions into 2’s and 3’s, resulting in duplets and triplets, respectively; and 2) subdivisions according to complex ratios, resulting in polyrhythms. We tested the model acoustically by having a group of 14 participants read unfamiliar sentences aloud and examining the extent to which their timing conformed with the predictions of a priori rhythmic transcriptions of the sentences. The observed patterns of variability in speech timing for these sentences, when measured at the bar level of the transcription, were generally consistent with the musical model.