Glitched arrow sound

When i found a cool redstone torch burnout glitch, I made them shoot arrows really fast. I put one stack in and they emptied fast. Then I heard shot arrow noises by the arrows

Arrows ran out in dispensers, expected for a empty dispenser sound

The arrows made a noise like when you fire them

Steps to Reproduce:
1. put a block down with a block diagonally above it
2. put a block diagonally above again; so here it is with a birds eye view( [] =block) []
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Side view []
3. place redstone on top, redstone torches underneath,and then place 3 dispensers.