तथैवोपरिपाणिश्च गीतवाद्यसमाश्रयः । लये नयं समं वाद्यं समपाणिः प्रकीर्त्यते ॥ ३३५॥
Similarly, Uparipāṇi (the upper beat) also applies equally to vocal and instrumental music. When the instrumental time (laya) is kept evenly in rhythm, it is called Samapāṇi (the even beat).
english translation