This paper reports on tests of three different stress-timing effects in a corpus of spontaneous utterances, elicited in a task which prompted naive speakers to produce many tokens of relevant target phrases. Several independent transcriptions of stress and intonation patterns were obtained. The intonation markings were used to control for phrase boundaries in interpreting duration measurements for polysyllabic shortening and stress clash effects. The first, but not the second is robustly demonstrated. The intonation patterns and stress transcriptions were also used to understand stress shift and to show where it will occur. The results show the intricate link between intonation and rhythm, making it crucial to obtain judgments of accent and intonational phrasing in experiments on speech rhythms in languages like English.