When we say the alarm goes off, we mean that the alarm starts to make a sound. 我们说闹钟响了是指闹钟开始发出声音了。
Your alarm, "alarm," is a machine that makes noise at a certain time; usually it has a clock. 你的闹钟，“alarm”是在某个特定时间发出噪音的机器，一般它都有个时钟。
Well, "I sometimes wake up before my alarm" makes noise--my alarm goes off. “有时候我会在闹钟”制造噪音——闹钟响之前醒来。
"I like to keep the alarm at a low volume," meaning not very loud, "at a low volume, with some classical music, nothing too jarring." “我喜欢把闹钟的声音调小”的意思是声音不大，“声音调小，放一些古典音乐，一点也不刺耳”。
When we say a sound is jarring, "jarring," we mean that it is loud and it causes you to jump or to be surprised. 我们说某种声音刺耳，“jarring”是指它声音很大，会让你跳起来或吓到。
It's something that is not very nice--not very pleasant. 这种东西不太友好——不太愉快。
A jarring noise would be one that bothers you, perhaps because it is very loud or it is not a very nice sound. 刺耳的声音会让你心烦，可能是因为它音量太大或者听起来不太友好。
So, I don't want my alarm to have a jarring noise, instead I play classical music. 所以，我不想让我的闹钟声音太刺耳，而是放一些古典音乐。
