But as the passenger jet climbed to about nine hundred meters in the air, something happened.

VOA: special.2009.04.01

That means, if you are going in a plane and you throw something up in the air, it seems to be going up and down to you.

也就是说,如果你在飞机中,你向空中扔出一物体,它也许会相对于你上下运动

耶鲁公开课 - 基础物理课程节选

In this case, the basic column of air is twelve and a half feet long and there are something called "Partials" or the "Harmonic series" That happens in anything, on a string instrument or whatever, but on the horn it's very distinct and that's what makes the different notes.

像这样,基本空气柱有十二个,每个半英尺长,圆号能发出分音,或泛音列,弦乐器或是,其他别的乐器中都有,但在圆号上,效果相当不同,这就是它能奏出不同音符的原因

耶鲁公开课 - 聆听音乐课程节选