Saxophonist Benjamin Herman.

Saxophone Science!

Saxophonist Benjamin Herman. (Saxophone Science)
Saxophonist Benjamin Herman. Photo Credit: flickr.com (Phillips Communications)

People have long been mesmerized by the smooth and rich sound of the saxophone, as spurred forward by legendary musicians such as John Coltrane.  While the sax has seen diminished popularity in recent times, it helped to define the jazz movement from the mid 1920s onwards and thus remains a key stepping stone in musical history.  The diversity of sounds capable of being produced in such a seemingly polished manner seems unreal at times, and while the talent of some of these saxophonists may be incomprehensible to most, a little bit of science can go a long way towards understanding how this music is produced.  First and foremost, it is important to understand that the saxophone is a single-reed woodwind instrument; that is, a sax contains a single reed mounted to a mouthpiece and connected to a resonator tube, where the action of blowing through this reed-mouthpiece combo creates resonance in the resonator tube, leading to the production of sound.  In order to start the process, the player must blow slightly pressurized air in between the reed and mouthpiece, providing a roughly constant input of energized fluid (air) into the system (instrument).  The reed, however, is not perfectly rigid (it has a certain stiffness associated with it) and thus can deflect.  If the input air is not pressurized enough, the flow rate through the mouthpiece will not be high enough to produce resonance; if the air is too pressurized (the player blows into the mouthpiece too hard), the reed will deflect too far and block the opening altogether.  The slight vibrations (and thus deflections) of the reed, in combination with the pressure & flow of the incoming air and the air in the reservoir of the resonator tube, lead to an oscillatory component for both the flow & pressure (the flow and pressure oscillate, vibrating the air in the resonator tube.  This in turn leads to the radiation of sound out of the bell on the far end of the tube, as well as through any other open holes/orifices.  For un-sustained notes, the outgoing sound often drops off quite quickly in an almost chop when the player stops blowing/providing air input due to the extremely high viscous losses due to frictional contact between the air and the walls of the instrument, as well as a relatively minor amount of thermal losses associated with the warming of the materials in contact with these acoustic vibrations.  Lastly, because the air reservoir in the resonator tube has certain resonant natural frequencies associated with it, the entire system will resonate much easier at specific frequencies, providing the pitch of the instrument, which the player can manipulate through proper key combination.  In the hands of a skilled musician, the saxophone is a very powerful instrument, capable of producing a great variety of high-caliber sounds (and as a side note: smooth jazz…GREAT study tool in terms of background noise, honestly; especially in combination with a hot cup of coffee.  Give it a try!).  Perhaps now you might be willing to check out some of that “old time” music that came about long before the days of auto-tuning and dubstep remixes!

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