I put the audio file for the Lavender Town theme through a spectogram program to see the actual frequencies of the audio, and this image appeared toward the end of the song.
Toward the beginning of the song another image appears, but it is only of the ghost with no Unown lettering.
After this part of the audio, the frequencies get a lot more frequent, and a lot more high-pitch, until the song eventually ends. When the audio of the ghost plays, it causes a lot of distortion.
I checked this myself, the picture was taken today.