Just how do you pronounce Aulë's Valarin Name

[piosenniel]

Perhaps you can puzzle it out from HERE (The Ardalambion Site).

& you can try emailing the author of the site; he's a helpful guy.

Originally Posted by Ardalambion

"The tongues and voices of the Valar are great and stern," Rúmil of Tirion wrote, "and yet also swift and subtle in movement, making sounds that we find hard to counterfeit; and their words are mostly long and rapid, like the glitter of swords, like the rush of leaves in a great wind or the fall of stones in the mountains." Pengolodh is less lyrical, and also less courteous: "Plainly the effect of Valarin upon Elvish ears was not pleasing." (WJ:398) Valarin employed many sounds that were alien to the Eldarin languages.