Picture it: you're chilling with your honey, just behind a curtain of moss. The day has been sweet and the chillaxing has been epic. Lying together silently, you're together in the moment. What's the sound? Whatever it is, it's going to be soft and harmonic: the lull of crickets or perhaps just your breathing. Sound-wise, this poem is in tune with all that. On a sonic level, it adds to the scene its soft, subtle harmonies.
Firstly, these lines are musical and measured, with many inverted sentences that hold the subject in suspension, waiting just as the scene and lovers are: "Upon the floor of light, and time, / Unmurmuring, of polyp made, / We rest" (9-11). Through the inverted syntax, we're left to leap across enjambments, pauses in mid-thought, to arrive at the final sense of the lines (just where and how the couple rests). Pauses and inversions like this one are places where the sounds of the lines would stop, giving us some silence in which to reflect before we head into the next line.
It's not all silent, though. There are also sonic harmonies in the poem's use of sound. For example, just check out how much alliteration this poem has going on: the L's in "layered light" (2), W's in "waiting, we" (5) and "We rest; we are" (11), the D's in "long drag […] the depth" (18) and "Disturbed the doe" (32). These aren't exactly tongue-twisters, hitting you over the head with their sound connections (like "Susie sells seashells by the seashore"). Instead, we get short bursts of connections, as we do with the poem's use of assonance. Just take a minute and read this section of the poem out loud (go ahead, nobody's watching):
Passion and slaughter, ruth, decay
Descended, whispered grain by grain,
Silted down swaying streams, to lay
Foundation for our voicelessness.
All our debate is voiceless here,
As all our rage, the rage of stone (21-26)
Did you notice all those long A sounds ("decay," "grain," "swaying," "lay," debate," and "rage")? If not, don't feel bad. Much like the soft singing of the crickets, this poem's sounds aren't cranked up to 11. Those harmonies are there, but you have to look—listen—for them, much like our speaker is attuned to the moment.