When a skeleton mob head is placed on a noteblock, the noteblock plays the skeletons “footstep” noises and not its “ambient” noise. Other mob heads on noteblocks play their ambient noises (creeper excluded due to no ambient noise of course) so this seems unintentional. I quite enjoy the almost wind chime noises skeletons make ambiently and was dissapointed I could not reproduce it.
Thank you for your report!
We're tracking this issue in MCPE-164530, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Issue Guidelines – 💬 Mojang Support – 📧 Suggestions – 📖 Minecraft Wiki