I bought the course because the reviews were good, but the noise is so annoying that I can't listen to the lecture. I asked about it, and there was a notice about noise, so I was going to watch the video and comment on the parts where the noise appeared, but one day, the notice suddenly disappeared. They just deleted it. Those who are actually taking this course should only buy it if they are confident that they can tolerate the noise. I paid a lot of money, and I don't know how I'm supposed to listen to the lecture.