What is that?
In 1988, I bought a Yamaha WX7 wind controller, and music making has never been quite the same. Invariably, I get the question, "What is it." The fullest, most complete answer would be rewarding with punishment, so my usual short reply is "It's an electronic instrument. You play it like a saxophone but makes no sound of its own. It plugs into THAT (pointing to the synthesizer module), which generates the sound, and that can pretty much sound like anything."
As to the Why of the wind controller, it is like carrying a truckload of instruments in a briefcase. If the mood of the music demands a violin or trumpet or whatever, it is available with a few button presses. If you want a different playing response, you can change it. If you want to sound like two instruments playing in unison, (e.g. a flute with an oboe), you can layer them. There are other reasons, but it's safe to say, "If you can imagine it, you can probably do it."
The chief disadvantage of wind synthesis is it can be difficult or impossible to fully duplicate the response and playing characteristics of a given instrument. This is especially true of bowed instruments (e.g., violin or cello), where you must stop blowing occasionally to breathe, and you are generally limited to playing the sound of one string at a time.
Regardless of realism, the wind controller visual can ruin the ceremony of a musician making music for the listener. When we hear a trumpet, we expect to see a trumpet. Seeing anything else tends to throw a speed bump into the listening process. Playing a wind controller unseen, such as in a pit orchestra or choir loft, can make this a non-issue.
Sound module — the "Brains"
What usually escapes further query is the synthesizer module, which is probably more relevant to the original question than the wind controller. The WX7 makes no sound of its own, so the final result depends heavily on the basic sound quality and programmability of the module. I've used Yamaha, Korg, Yamaha, and Roland modules with the WX7. Most are "sample playback" units, where playing a note sounds a recorded snip of the instrument that has been looped and filtered to produce a sustained tone.
As a rule, I've needed to reprogram patches to optimize each module for the WX7. My current modules include the Roland JV-1010, XV-2020, and XV-5080 modules. Selections at the right were played using a Roland JD-990.
Wind synthesis — the Artistry
Playing a wind synthesizer might seem like a "free lunch." Many aspects of traditional instruments (mouthpiece embouchure, reed or string selection, unique playing techniques, etc.) are removed from the equation. However the wind player must substitute expertise in programming, an understanding of the physics of multiple instruments, and a mastery of each playing style. In either case, there remains the need for proficiency, inspiration, and musicianship.
Make no mistake: there is no substitute for a real instrument and its unique capabilities and tonality. Nothing can replace a Stradivarius -- maybe not even another Strad. With this in mind, playing a wind synthesizer as a means of realizing a musical vision and enhancing the musical experience is, nonetheless, perfectly valid. Having artistry completely transcend technology, so that thought translates directly into music, is the mark.
About the recordings
The MP3 audio files linked on the right of this page were recorded with a Zoom H4 Handy Recorder. A Roland electronic keyboard, Roland JD990 synthesizer module, and Shure SM58 microphone were fed into a Dod R855 mixer. The keyboard and JD990 were panned left and right, and the microphone centered in the sound field to permit some balance adjustment of keyboard or synthesizer levels relative to vocals during the final mix. The raw audio files were processed using Audacity software.
Article about programming modules for wind control: Windworks Design blog