Possible Clues:

• Complaint from groom, losing space for horse
• Sigh with pain
• Low sound, developed sound
• Adverse reaction to corn?
• Organ (anag) — lament
• Make a complaining sound
• "Aw, mom!" sound
• Sound from a haunted house
• 'Oh, that's a horrible pun' reaction
• Response to a stupid joke in new organ