Tempo, or the speed at which a piece of music is performed, refers to its measure, beat, or pulse. Tempo is affected by many factors, such as the size and acoustical characteristics of the performance venue, the size of the ensemble, and the particular instruments being used. Certain musical factors also determine the character of the piece, such as its meter, predominant rhythmic motion, and the meaning of the words (if voices are present). The tempo of a piece may even vary slightly depending on one’s state of mind or how one feels at the time. When we speak of the correct tempo for a piece, it is understood that a given speed will allow for minor adjustment according to the circumstances of individual performance.