What is the official way to differentiate between a woodwind and a brass instrument? I know it's not about the material that they are made of, but how the sound is produced.

4 Answers 4


All instruments denoted "brass" require flapping lips (no jokes pls :-) ) to produce the acoustic frequency. Woodwinds do not. <-- So it's not so much being a reed instrument, rather that the instrument contains the oscillating element. Flutes and recorders (aka blockflote, whereas flutes are "querflotes") use an air chamber of one shape or another to initiate the oscillation. But just to muck things up, a French Horn is an honorary member of a "Woodwind Quintet."

  • @Caleb I was trying to be humorous :-( . Maybe I should have written "French Horn is an honorary woodwind ... and always appears in WQs" Dec 18, 2016 at 14:31
  • Oh goodness. I've even made that joke! I'm so sorry! My sense of humor has been broken!!
    – Caleb
    Dec 18, 2016 at 15:05

Woodwind instruments are generally made to play with wind (players breath) being blown past a reed or reeds. The obvious odd ones are recorders and flutes, which don't have reeds, but still produce sound when wind is blown through or over them.

Brass instruments, however, won't make much noise when blown into in the way one blows into a recorder.A 'raspberry' needs to be produced with the lips close together, on the mouthpiece. All brass instruments will fall into this category, from trumpets to Sousaphones.

Saxophones, whilst often brass looking, have reeds, so will belong to woodwind.

Going back several centuries, brass instruments were generally made from such, and woodwind similarly.

  • As per @Carl’s answer, while recorders and flutes don’t have a separate reed, they do still have an edge which air is blown over to produce the oscillations — from an acoustic point of view, they have something equivalent to a reed.
    – PLL
    Jan 27, 2014 at 16:56
  • Does then the shape or the sound produced of the instrument has anything to do about its clasification?
    – SysDragon
    Jan 28, 2014 at 8:10
  • 2
    I don't believe so. Some have parallel tube shapes inside, some conical. Most have a bell, but the sound of a flute comes from the mouthpiece area.Generally a brass instrument will sound harsher than one made from wood- the french horn being an exception - that's why it's 'allowed' into the woodwind (wind) quintet.
    – Tim
    Jan 28, 2014 at 8:31

You may be interested in the Hornbostel-Sachs system of musical instrument classification. It is very similar to the Dewey Decimal system for libraries.

The instruments you are talking about are all within the Non-free aerophones group (42) which is further broken down into:

  • Edge-blown aerophones/flutes (421)
  • Reed aerophones (422)
  • Trumpets (423)

The generic terminology classifies groups 421 and 422 as "woodwinds", and group 423 as "brass". This list contains detail about the Hornbostel-Sachs aerophones, including simple definitions for each subgroup, as well as examples included.


Most of the time, the classification is made by how the sound is produced. If it is produced by wooden reeds or if the instrument is a flute, then it’s a woodwind. If the sound is produced by lips on a mouthpiece, it’s a brass instrument.

A former professor of mine, however, proposed it might make more sense to separate woodwinds and brass instruments by another criterion: what its pipe looks like. If its a tube and if the player play a pitch using harmonics or changing the length of the tube (with a valve or slide), then it’s a brass. It it’s a pipe pierced with holes you can open or close, then it’s a woodwind. This, however, is not usually considered standard.

For most instrument, both criteria yield he same results. The only exception I can think of is the cornett, which uses a brass-like mouthpiece with a woodwind-like body.

  • 1
    Other instruments which would defy your professor's classification are the Ophicleide, the Serpent and related Anaconda, the Keyed Bugle and the Keyed Trumpet, which are all Brass instruments, but played with pads covering holes in the instrument body. All of these pre-dated, and were eventually replaced by, valved instruments.
    – yorkie
    Jan 31, 2014 at 23:03
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    @tubadaz I wouldn’t say defy. The choice of classifying these instrument with woodwinds was voluntary. (And I tend to think of the serpent as a bass cornett).
    – Édouard
    Feb 1, 2014 at 1:32
  • I think you are probably correct in thinking of the Serpent in that way. As a low brass player I am so used to thinking of the Serpent as a sort of early proto-tuba that I totally neglect the actual origin of the instrument. Thank you for pointing that out.
    – yorkie
    Feb 4, 2014 at 23:02

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