“Is this a serious problem?”

It usually happens when I’m relaxed, sitting, and quite weirdly, listening to music. I suddenly get this feeling of heaviness on my chest, my pulse speeds up, the time slows down and I hear incoherent voices in the back of my mind muttering something over and over, telling me to do something, or hating on me, but I can never understand a word they’re saying, I just feel that they are saying mean stuff. It usually goes away in 3-4 mins, but it always scares the sh** out of me. These “situations” occur once or twice a month. It also must have some connection with my sleeping pattern, when I sleep less, it occurs more frequently.