Build 10074's sounds were highly dynamic. They used complex stereo field mixing (where sounds moved from left to right) and deep bass frequencies. Beta testers on cheap laptop speakers reported clipping and distortion. The sounds also caused a memory leak in certain Realtek audio drivers. Rather than fix the drivers, Microsoft simplified the sounds to generic MIDI-like tones.
While many sounds were similar to the final RTM (Release to Manufacturing) version, this build featured distinct versions of: windows 10 build 10074 sounds