They were appalled at the loudness of his snoring.他雷鸣般的鼾声把他们吓到了。

the right speed, loudness and rhythm正确的速度、音量和节奏

The students began to enter the classroom and Anna was startled at their loudness.学生们开始进入教室了, 吵闹声把安娜吓了一跳。