On our sister blog, Science & the Arts, there is another wonderful guest post by Dr. John Powell, author of How Music Works. This one answers this question: "Why is an oboe louder than a flute? He writes:
The reason why the clarinet and oboe can be played louder than a flute or recorder is because these latter two instruments depend on a stream of wind fluttering regularly up and down over a sharp edge. When the flutter goes mostly below the edge, a puff of pressure is sent down the tube of the flute... But these puffs of pressure are not as energetic as the ones produced by closing and the suddenly opening a reed or beak.
He goes on to explain that you can test this phenomenon for yourself by blowing across the open neck of an empty bottle then comparing that sound to the sound you can make from a homemade drinking straw oboe. Details for making your own oboe from a straw (and a video of Dr. Powell discussing the instrument) at http://www.sciencefriday.com/arts/2010/11/how-music-works-the-magnificent-drinking-straw-oboe-the-mellifluous-beer-bottle-flute/
You can hear Dr. Powell's segment on Science Friday at: http://www.sciencefriday.com/program/archives/201011192 (media player on upper left of screen.)