However, on the whole, our sense of time passing is based on observation of external events and a sense of change within ourselves or our environment. The external events help us keep track of clock time. That's because you have done it before, and if you know it usually takes you half an hour, then you can take into account the fact that you rushed through everything, therefore that was probably 5 minutes saved. Ok, then there's the other type of time sense. It has to do with expectations being fulfilled or not, and with the amount of data being processed.
Information theory comes in useful here.
The perception of time is often calculated by the amount of change that is happening. Of course, this can easily happen in musical contexts as well. I am writing this off the top of my head, so to speak, so please tell me if it doesn't make sense. Additive rhythm some other day.