Update: According to Kotaku, someone claiming to be a Bethesda employee and who has posted on behalf of the company in the past stated:
We’re currently testing a fix and hope to have an update out next week.
LasurArkinshade has also written that the soundfiles of the PS4 version seem to be of a much higher quality than PC version of Special Edition and even better than the original's. He said it was almost "to the point where it almost seems like Bethesda intended to push out higher quality audio for the Special Edition but didn’t include those files in the PC/Xbox One versions, possibly by mistake or as an oversight. "
The Skyrim Special Edition was released earlier this week with much fanfare. However, SoundCloud user Lasur Arkinshade has posted an interesting audio file the same clip of music from the original version and the upgraded Special Edition version. According to Arkinshade, the sound has notably degraded between the two due to a file format change from .wav to .xwm which reduces the audio size but has a negative effect on the quality.
A comparison between the level up sound in vanilla Skyrim and the extremely heavily-compressed level up sound in the Skyrim Special Edition. This is a demonstration of the quality degradation that has taken place across the game's audio.