When I am stopped in traffic, every now and then I hear a kind of musical "plink... plink plink" sound from, I believe, the left side of the engine area. It almost sounds like a dripping water faucet. The sound is faint enough that if I have music on, I won't hear it. I'm sure it's a normal part of the hybrid system doing its thing, I'm just curious what the sound actually is. Any ideas?
At first, I only noticed it after the car had been running a while... but this morning I heard it almost immediately upon start up. I'm not concerned, I don't think it's a problem, but it's a rather quite little sound and I'm curious.
I hear an occasional Pop sound like crushing a plastic soda liter in the rear of the car on occasion. I hear that the Prius will make strange sounds and that is normal.
I have not heard this sound and I rarely listen to the radio in my C. Your description "sounds" like the noise from heat shields in the engine compartment that are heating up or cooling down. There are several thin sheet metal heat shields that surround the exhaust system. Expansion and contraction can cause them to "plink". I suspect that in traffic, the engine shuts off and some of these shields can start to cool off causing the metal to contract. Typically the individual metallic like pings will change in frequency -- slowing down as the part cools off. If this is the source of the sound, it is nothing to worry about. Outside temperature can determine if the shields will make noise.