— This paper presents a beat-counting robot that can count musical beats aloud, i.e., speak “one, two, three, four, one, two, ...” along music, while listening to music by using its own ears. Music-understanding robots that interact with humans should be able not only to recognize music internally, but also to express their own internal states. To develop our beatcounting robot, we have tackled three issues: (1) recognition of hierarchical beat structures, (2) expression of these structures by counting beats, and (3) suppression of counting voice (selfgenerated sound) in sound mixtures recorded by ears. The main issue is (3) because the interference of counting voice in music causes the decrease of the beat recognition accuracy. So we designed the architecture for music-understanding robot that is capable of dealing with the issue of self-generated sounds. To solve these issues, we took the following approaches: (1) beat structure prediction based on musical knowledge on chords a...