"Portrait d'une Femme" is filled with miscellaneous objects and experiences that the speaker associates with the woman, a "sea-hoard of deciduous things" (25). This phrase perfectly exemplifies the poem's overall sound, which we would characterize as the sound of seawater sweeping across a sandy beach.
Words with smooth consonants, especially "s" and "l," dominate the poem, which creates a rhythmic swish throughout the lines. You can hear this really strongly in the lines "Ideas, old gossip, oddments of all things" (4) and "In the slow float of differing light and deep" (27). The rotation of unstressed and stressed syllables in the iambic pentameter lines adds to this effect.
If we move from the seashore to an indoor location, where the speaker might be sitting with the woman, we can imagine the speaker's voice as a meditative whisper floating through a dark, candlelit room, accompanied by the repetitive flickering of the candles' flames.