स यथा दुन्दुभेर्हन्यमानस्य न बाह्या-ञ्शब्दान्शक्नुयाद्ग्रहणाय दुन्दुभेस्तु ग्र-हणेन दुन्दुभ्याघातस्य वा शब्दो गृ-हीतः ॥ ७ ॥
In plain words
Here is how it is. When a drum is struck, you can't get hold of its scattered sounds one by one. But grasp the drum itself, or the beating of it, and the sound is grasped whole.
Close to the Sanskrit
It is like this: as, of a drum being struck, one is not able to grasp the external sounds [separately]; but by the grasping of the drum, or of the beating of the drum, the sound is grasped.