When Sam put on the Ring, Sam also experienced enhanced senses.
Puddleglum’s answer is obviously a right one, that Tolkien, when he first wrote about the Ring, had not considered it as more than a magic ring of invisibility of indeterminate origins. That said, this answer does not work for a reader who is reading
The Hobbit and
The Lord of the Rings as views of a coherent world.
But when Frodo first puts on the Ring in Tom Bombadil’s house there is no indication that Frodo experiences anything more untoward than Bilbo. The same is true when Frodo accidentally puts on the Ring at
The Prancing Pony. When Frodo puts on the Ring at Weathertop, the only sign of enhanced senses is that Frodo now sees beneath the black wrappings of the Ringwraiths and they appear clearly to Frodo, their long grey robes and silver helms visible. Bilbo and not encountered wraiths of any sort, nor had Frodo previously when wearing the Ring.
Frodo, at the end of his flight to Rivendell, again sees the wraiths more clearly, but this is connected with Frodo’s morgul-wound, not with the Ring. Frodo is not wearing the Ring.
It is only when Frodo puts on the Ring at Amon Hen that he sees more than he should see naturally and that he perceives the Eye almost see him. Immediately before providing the visions seen by Frodo, Tolkien writes:
He seemed to be in a world of mist in which there were only Shadows: the Ring was on him.
But for Tolkien’s mention of the Ring in connection with where Frodo seems to be, the reader might be content to imagine some enchantment of Amon Hen, ‘the Hilll of Sight’, and possibly some enchantment of Amon Hen
is also involved.
Frodo never puts on the Ring again until the last time.
Only when Sam puts the Ring on is Sam at once “aware that hearing was sharpened while sight was dimmed”, something not said before. The Ring translates the meaning of the Orcs who are not speaking in the Common Speech. Tokien writes:
He [Sam] heard them [the Orcs] both clearly, and he understood what they said. Perhaps the Ring gave understanding of tongues, or simply understanding, especially of the servants of Sauron its maker, so that if he gave heed, he understood and translated the thought to himself. Certainly the Ring had grown greatly in power as it approached the places of its forging; but one thing it did not confer, and that was courage.
Amon Hen was not far away and the increase in power of the Ring as it approached Mount Doom would also explain the additional power the Ring showed when Frodo wore it not long before.
One might also suggest that the Elves of Mirkwood mostly spoke their own Silvan Elvish tongue among themselves and that this was translated in Bilbo’s understanding to the Common Speech, although Bilbo was unaware that this was occurring and, at that time, the Ring was nowhere near Mount Doom.