Caliban said:
For what it's worth, I believe the FAQ was incorrect in it's original ruling regarding Acid and Sonic ignoring hardness, and agree with Andy's current ruling (although he did his usual sloppy editing job and missed a contradictory answer elsewhere in the FAQ).
Energy powers in the Expanded Psionics Handbook ignore hardness for sonic attacks.
Breath of the Dragon in the same book (acid attack) does not mention this.
Sympathic Vibration (PHB) also ignores hardness. This is the only sonic attack that I can find in the PHB that does.
None of the other sonic or acid spells in the PHB ignore hardness.
But, the PHB seems to be fairly clear if you read more than just the Energy Attacks section: "Whenever an object takes damage, subtract it's hardness from the damage.".
If there is an exception to this rule, it has to be clearly called out. "Acid and Sonic attacks deal damage to most objects just as they do to creatures, roll damage and apply it normally." does not clearly call out an exception to the rule.
How do you apply damage to creatures? You roll total damage, you subtract out any appropriate resistances, you give the final total to the creature in hit point damage.
So, you do the same with damage against objects. If the object has hardness, you subtract it because the Acid and Sonic damage section does not state that you do not. It is merely stating that you use full acid/sonic damage against an object (as opposed to half for fire/lightning and quarter damage by cold).
Learn something new every day.