You are paying good money for the class and you have the right to attend without annoyance. If you can't hear the speaker easily, see if you can move your seat so that you are closer to the person speaking. If you find you keep thinking about the speaker's outfit, hair style or gestures, remind yourself why you are sitting there in the first place. At home, you need to plan your study area that is discussed in Chapter 6. You won't be able to eliminate all external distractions, but you should be able to reduce those distractions to a minimum.
Internal distractions can be either physical or psychological.
Physical distractions include feeling hungry, tired, having a headache or a sore back, while psychological distractions include being concerned about a personal problem, remembering that you need to stop at the store on your way home, or pay the rent, or just being worried about too much to do, too little time. Often, pre-planning can reduce physical discomfort. Perhaps taking a cushion for a hard chair or changing from an office outfit to more relaxed clothing would make you more physically comfortable. Personal problems and time pressures can often be set aside for a time by jotting a note to yourself on a separate note pad you have for this purpose. Once you have formed a habit of writing notes and checking those notes after class, you can forget trying to remember whatever it is that has popped into your head.