Water dripping into metal buckets in the kitchen.
Let me back up a bit: we were removing a bath from the en suite bathroom today. Much shooting of water from the decapitated tap pipes until I could cap them off. Water flowed down through floorboards, dripping into kitchen.
Make sense now?
The sound reminds me of some pretentious contemporary "experimental" classical music that Radio 3 would play late in the evening. It just lacks the person in Row 3 coughing.