A couple of examples of sound reinforcing sense in the Aeneid. I’m nearly certain that none of these are original, but I’m just jotting them down as I read through.
So, to begin, two examples that have to do with water. First, when Neptune becomes aware of the storm caused by Aeolus at Juno’s behest:
Interea magno misceri murmure pontum
emissamque hiemem sensit Neptunus… (A. 1.124-5)
The alliteration of the letter “m” gives a sense of the heaviness of the storm, reinforced in the first line by the slow rhythm of “magno misceri mur-” and the onomatopoeic “murmure” and by the heavy line-initial “emissam.” The main verb (sensit) and subject (Neptunus) are delayed, so that the reader is made to perceive the storm from this angle along with Neptune, or even before him, but from his perspective.
“Murmure” is picked up again later in Venus’ complaint to Jupiter about the fate of Aeneas and his men:
Antenor potuit mediis elapsus Achivis
Illyricos penetrare sinus atque intima tutus
regna Liburnorum et fontem superare Timavi,
unde per ora novem vasto cum murmure montis
it mare proruptum et pelago premit arva sonanti. (A. 1.242-6)
Again, the alliteration of “m” is effective, and the line-ending “murmure montis” is particularly striking. The alliteration is transferred to “p” in the final line, which contributes to the quick pace of the line and points us to the swiftness of the water. Indeed, the line’s only heavy segment is “proruptum et,” and these two (elided) words slow the line just a touch before the words “pelago premit” rush forward on the page and the river rushes forward onto the land.