Whenever you play a mob skull from a note block, the mob sounds played are lower pitched than they should be (compared to Java Edition). This can easily be displayed by comparing the note block sounds to the sounds actual skeletons make.
MCPE-164530
Mob sounds from note blocks are incorrectly pitched
Open
1
(Unassigned)
937204
Confirmed
Multiple
1.19.60.20 Preview, 1.20.81 Hotfix, 1.21.43 Hotfix
Retrieved
skeleton and wither skeleton skulls make their step sounds for some reason, rather than their ambient sounds. The sounds are lower pitched than when played with /playsound, though; the volume is about 0.9 and the pitch about 0.84.