So I have an oldish pair of headphones, specifically the Sony MDR-XD200. I have generally been very happy with them - I've been pondering getting something fancier, but have had a hard time justifying it as I'm pretty happy with how these sounded. I'm worried I might have done them in, though. A few minutes ago I was sitting at my computer with a blanket and wearing the headphones, I was starting to get a bit warm so I took off the blanket and threw it onto my couch. As soon as it left my hands, I heard this really strange sound over my headphones, like someone pouring sand or rice into something (i.e. rainstick). It went away gradually, but now I'm stuck in paranoid listening mode, trying to tell if I've wrecked my headphones or if they sound any different.
Can anybody explain what I did? Obviously something ESD-ish happened, but I've never heard of it manifesting like this.