Midrash for Sanhedrin 130:4

רבי יוחנן אמר חייב עקימת פיו הוי מעשה ר"ל אמר פטור עקימת פיו לא הוי מעשה

But does not R. Johanan regard sound as a [concrete] action? Has it not been stated: If one frightened [lit. 'muzzled'] off an animal by his voice, or drove animals by his voice,<span class="x" onmousemove="('comment',' The first refers to Deut. XXV, 4: Thou shalt not muzzle the ox when he treadeth out the corn; the second to Deut. XXII, 10, Thou shalt not plough with an ox and an ass together. ');">⁴</span>

Sifrei Devarim