A couple of weeks ago, I attempted to dive into the extensive and complicated history of how flutes are built to be in tune with themselves: their scale. To summarize, the flute scale determines how well the notes play in tune to each other, octave to octave, and also determines the timbral balance of the notes. From a mechanical standpoint the flute scale is a function of the following: the diameter of the flute tube or “bore,” the size of each tone hole, the linear location of each tone hole along the flute tube, and the height of each tone hole. Scale should not be confused with the pitch of an instrument. Pitch relates to which “A” the instrument has been designed to produce (e.g., A-440, A-442, etc.) Most instruments made for the U.S. market are typically pitched at A-442, and play well in tune from A-440 to A-444.
As we can see, this is a very complex and exact process, and also one with no clear-cut answer or one size fits all method. For flutes that have been built since the mid 1900s, most of them have been constructed using either the Cooper scale or, later, the Bennett scale, along with some other varieties.

Theobald Boehm, as we discussed last week, developed the basis for today’s flute scales. Verne Powell, the creator of Powell flutes, experimented with a less problematic scale when he started producing his own flutes in 1927. Interestingly enough, the next major improvement in scale design was accomplished by Albert Cooper in the mid-1970s. Cooper figured up a “displacement graph” that enabled other makers to use this calculation. Through his studies, he also improved upon the Boehm system of tuning so that the scale was more reliable. All of this work resulted in what we know today as the “Cooper Scale”. He shared it with his good friend flute maker William Bennett, who later changed the equation a bit to make the “Bennett Scale”. William Bennett’s continuous experiments with flute scales and the diameter and height of the tone holes has been largely responsible for this revision of Cooper’s. While these scales are not perfect and many flutists still complain of their C# being much too sharp while other notes are too flat, this is the basis of what our modern day scale is. Many flute makers still use these scales, while others have made improvements and changes to these scales giving their flutes a slightly different sound from other makers.

And there you have it! A straightfoward roundabout history of the ever-challenging history of building a flute to be in tune with itself. Questions or comments? Leave them below or shoot me an email!