Tennyson uses onomatopoeic language throughout the poem to mimic the sound of the brook. In the first stanza, the brook is described as "sparkl(ing)" and "bicker(ing)." The repetition of the "k" sound in the middle of both words suggests the tinkling sound of the water as it rolls through the ferns.

In stanza four, words like "chatter," "bubble," and "babble" suggest a gentle, bubbling sound, describing the water passing over stones and pebbles. In the last two lines of stanza four, there is a concentrated repetition of the letter "b" in "bubble ... bays ... babble ... pebbles." The repetition of this letter, and the sound it denotes, suggests that the sound of the water is building, and becoming louder and busier.

In stanza six, Tennyson describes the water as "chatter(ing)," and in the penultimate stanza he describes the water "murmur(ing)." These descriptions personify the river, and suggest that it is making sounds much like a human might. These particular words still imply that the water is relatively quiet, but there is a sense that the river is gradually becoming noisier, and busier.