Our study investigated the pitch and duration properties of word stress in a large speech corpus. We concluded that pitch and duration play different roles in distinguishing word-level stress classes. In the case of pitch, primary-stress vowels were different from secondary-stress and reduced vowels; in the case of duration, reduced vowels were different from the other two types of vowels.
Bibliographic reference. Yuan, Jiahong / Isard, Stephen / Liberman, Mark (2008): "Different roles of pitch and duration in distinguishing word stress in English", In INTERSPEECH-2008, 885.