a device that makes a regular sound like a clock and is used by musicians to help them keep the correct rhythm when playing a piece of music
metronomic
ˌmetrəˈnɒmɪk 
ˌmetrəˈnɑːmɪk 
Definition of metronome noun from the Oxford Advanced Learner's Dictionary
ˌmetrəˈnɒmɪk ˌmetrəˈnɑːmɪk 