Vaiśeṣika Sūtra 2.2.34

2.2.34

kāraṇo vikārāt |

na—not; ca—and; asiddham—disproved, Vikārāt from change.

29. Nor is (the dependence of Sound upon a cause) disproved by its modifications.

From observing the loudness, softness, and other modifications, it should not be concluded that the possession of a cause by Sound is thereby disproved. For a loud or soft sound is perceived according to the hardness or softness of the beating of the drum with the drumstick, and the like; whereas the loudness, etc., (i.e., the intensity) of that which is made known, is not dependent on the loudness, etc., (i.e., the intensity) of that which makes it known. Hence from its undergoing modification according to the modification of the cause, it is inferred to be a product, and not something to be revealed only-—29.