This hotfix will be included in a later version of Audio Overhaul for Skyrim.
Because the direct cause of the issue cannot be easily worked around, it is possible this issue can be reintroduced with mods that add new locations. Or it could still happen in vanilla (I did not check everywhere)! This mod serves to document the issue and provide a simple fix for this location specifically.

DESCRIPTION

Changes the sound output model of OBJDwemerPistonA and OBJDwemerPistonB to reduce sound attenuation force, lowers priority for high CPU loads, changes the sound category to ambient, and provides an optional plugin to disable the problematic piston in Avanchnzel completely. Your mileage may vary.

ISSUE

In dwepipe1waypiston01.nif there are two keys in the animation to play back sound OBJDwemerPistonA and OBJDwemerPistonB.  When walking in a certain hallway in Avanchnzel you will likely hear an obnoxiously looping piston sound. Observation and reason: This piston animation loop in the hallway directly below you breaks after right around an animation key triggers a sound, the sound attenuation reaches at a distance further than the walls and the player hears noise. This issue is exasperated even further with mods that edit acoustic spaces and vanilla sound output models such as Audio Overhaul for Skyrim.

SOLUTION

The cleanest solution with the least compromises and highest degree of compatibility, in my opinion, is to just assign those two sound descriptors their own unique output model, lower the max distance the sound can travel, and assign them lower priority. This comes at the cost of changing every single piston in the game's max sound attenuation, but to no real noticeable difference in vanilla. With mods like Audio Overhaul for Skyrim, you will not hear the pistons as far throughout the ruin, but this might make more logical sense given how the dungeons are laid out and the foundation of the dungeon.

The piston sounds were also routed through the "ambience" category. This has less noticeable difference in Vanilla, because the ambient sound categories link right back to the "Effects" volume slider. The piston sounds will just be ducked during dialogue like most other similar sounds tied to dwemer ruins. Use Audio Overhaul for Skyrim if you want the channel routing fixes.

I've also provided a file to yeet the problematic piston to the end dimension, see you loser. Idiot.

RECOGNITION

Thanks to Ai Elias for helping test certain locations and helping me figure out a working solution to the bug.
Thanks to powerofthree for pointing me in the direction of the animation keys under NiTextExtraData.