[Galin]

Originally Posted by Lissë

(...) I think in the Lost Tales there is a passage where the elves of Gondolin are astonished at Tuors deep voice. Does anyone else know this passage? Did Tolkien imagine elves with higher voices than humans? Thank you!

I don't think The Book of Lost Tales is the best reference for how Tolkien ultimately imagined his Elves. JRRT does note that the Gnomes were slender here, but also small...

'Tis written that in those days the fathers of the fathers of Men were of less stature than Men now are, and the children of Elfinesse of greater growth, yet was Tuor taller than any that stood there. Indeed the Gondothlim were not bent of back as some of their unhappy kin became, labouring without rest at delving and hammering for Melko, but small were they and slender and very lithe.'

JRRT, The Book of Lost Tales, The Fall of Gondolin

It's also noted that the Noldoli that came forth to see Tuor marvelled at his stature and gaunt limbs. At the moment I'm not sure about slenderness but I think maybe the Elves of the Lost Tales were notably shorter than they would later become, especially considering some old descriptions, including:

Nuin's words to Tu on the stature of the sleepers in the vale of Murmenalda are curious. In A is added: 'Men were almost of a stature at first with Elves, the fairies being far greater and Men smaller than now. As the power of Men has grown the fairies have dwindled and Men waxed somewhat.' Other early statements indicate that Men and Elves were originally of very similar stature, and that the diminishing in that of the Elves was closely related to the coming of, and the dominance of, Men.

Nuin's words are therefore puzzling, especially since in A they immediately preceded the comment on the original similarity of size; for he can surely only mean that the sleepers in Murmenalda were very large by comparison with the Elves. That the sleepers were in fact children, not merely likened in some way to children, is made clear in D: 'Nuin finds the Slumbrous Dale (Murmenalda) where countless children lie'

Christopher Tolkien, The Book of Lost Tales

Nuin had said...

'(...) nor any the more when Nuin made an end of his tale, telling of all he saw there -- and methought,' said he, 'that all who slumbered there were children, yet was their stature that of the greatest of the Elves.'

The concept of the Elves and Men being of like height -- because Men were smaller 'back then' and Elves taller -- appears in the Lay of Turin, but when we get to the 'early Silmarillions' and Silmarillion-related texts of the 1930s we seem to move to simpler comparisons between Men and Elves -- that is, they are of like height, with Men somewhat taller (especially the Hadorians), but without the comparative reference to the stature of Men in earlier times versus 'now'.

And then again there are even later references to Elven height, compared to Men or Numenoreans.

I think the external chronology [when Tolkien wrote what text] is important here, even if it doesn't necessarily answer all our questions.