Exod. 19:13 There shall not an hand touch it, but he shall surely be stoned, or shot through; whether it be beast or man, it shall not live: when the trumpet soundeth long, they shall come up to the mount.
The Holy Spirit is emphatic in this account that there were no humans allowed to be on the mount, and yet there would be a long sounding of a trumpet (Exod. 19:13).
In that setting, the Spirit repeatedly and explicitly speaks concerning the sounding of a trumpet on this occasion and attests that such a sounding of the trumpet took place (Exod. 19:16, 19; 20:18):
Exod. 19:16 And it came to pass on the third day in the morning, that there were thunders and lightnings, and a thick cloud upon the mount, and the voice of the trumpet exceeding loud; so that all the people that was in the camp trembled.
Exod. 19:19 And when the voice of the trumpet sounded long, and waxed louder and louder, Moses spake, and God answered him by a voice.
Exod. 20:18 And all the people saw the thunderings, and the lightnings, and the noise of the trumpet, and the mountain smoking: and when the people saw it, they removed, and stood afar off.
These verses plainly teach us that instrumental music is not just a human activity---no humans were allowed on the mount; therefore, the trumpet that was sounded on this occasion was sounded by a supernatural, non-human being.
Those who teach that making instrumental music is only a human activity do not teach what is true according to Scripture.