The duration for the level 3 bard spell Wounding Whispers is currently at 1 round/level, which is shorter than similar spells (Death Armor, Elemental Shield, and Mestil's Acid Sheath, all 1 in-game hour). In addition, all of these other spells have additional effects, as such:
Death Armor (Level 2): 1d4 + 1 per level (max + 10) damage (magic), +2 natural armor bonus, material component: Black Onyx
Duration: 1 hour
Elemental Shield (Level 4): 1d6 + 1 per level (max + 15) damage (fire), 50% cold immunity, 50% fire immunity, material component: Glowworm
Duration: 1 hour
Mestil's Acid Sheath (Level 5): 1d6 + 1 per level damage (acid), 100% acid immunity, material component: Glass Statue of a Man
Duration: 1 hour
Wounding Whispers (Level 3): 1d6 + 1 per level (max + 15) damage (sonic)
Duration: 1 round/level
I understand that sonic damage is superior at least to acid and fire damage (probably not to magic), and that this spell does as much damage as elemental shield. The lack of material component is nice too, but there is no secondary effect, and in my opinion the duration of wounding whispers is far too short to be of any real use, at least at the levels when it is most appealing to take it.
Admittedly I am only suggesting this because I have a new bard character looking to make use of the spell, and a longer duration would really help in that endeavor, but I'd like to suggest raising the duration to either 1 in-game hour (as the other variations), or something like 5 rounds/level (maybe 3 rounds/level, if 5 is too much and 3 is even possible). It would certainly make it a much more usable spell.