Recently, communication, digital music creation, and computer storage technology has led to the dynamic increasing of online music repositories in both number and size, where automatic content-based indexing is critical for users to identify possible favorite music pieces. Timbre recognition is one of the important subtasks for such an indexing purpose. Lots of research has been carried out in exploring new sound features to describe the characteristics of a musical sound. The Moving Picture Expert Group (MPEG) provides a standard set of multimedia features, including low level acoustical features based on latest research in this area. This paper introduces our newly designed temporal features used for automatic indexing of musical sounds and evaluates them with MPEG7 descriptors, and other popular features.