And the answer has to do with ratios and string sizes and lengths of pipe and things like that, but generally speaking, pitches that are right next to each other--very close to each other--are dissonant.

答案和比率以及弦乐器的尺寸和管乐器的长度等有关，但是总的说来，音调是相关联的，非常近。

耶鲁公开课 - 聆听音乐课程节选