• Patrick Olwell

A Taxonomy of Tone Holes

Many discussions of the different types of simple-system flutes currently played in Irish music mention tone-hole size in comparing flutes, but the usefulness of terms like “small holes” or “medium holes” is limited without actual measurements. Hoping that it might prove useful to players and those interested in the similarities or differences between various flutes, here is some information about our in-house system of classification...

Right-Hand Tone Holes, Blackwod Pratten

We use the measurement of the #4 hole (which corresponds to the right hand index finger for a right-handed player) as the main reference point that describes the “size” of a flute—this corresponds with our Pratten, Nicholson, and Rudall-Rose models. The reason I started using the #4 hole is that I use the G and D scales to lay out the tonal “map” of the flute, and I use these triads in the first round of tuning each instrument as it is being made. (Note that we’re talking here about concert flutes in the key of D, but the same general rules and nomenclature apply to flutes in other keys.) I tend to think of the first octave G (and sometimes also the low D) as “home base” and G is usually the first note that I check using a tuner. Although somewhat a quirk of our making process, this system may also be related to the general layout of a six-holed transverse flute, as small D piccolos are called G flutes in China, and in India this note is also often the tonic. Another factor is the likelihood of a given note playing more true than another: the G-position note on simple-system flutes is often more dependable than the A, which tends to be unpredictable on 19th century London flutes as well as some others.

There is also the question of tone and feel. On simple-system flutes, the size of finger holes on one instrument relative to another affects the “voice” or character of tone that the flute will have. To my ear, a flute with smaller holes feels a bit more veiled, subdued, or not as “open” as one with larger holes (complicated by the fact that the bore and embouchure also have a significant impact on these qualities). This is important in choosing the sound and feel you prefer as a player.

Anyhow, in the interest of reducing the overall confusion regarding what constitutes small, medium, or large holes, here is our yardstick or classification system, which corresponds to our Pratten and Nicholson models etc...

#4 hole:

  • 6.0–6.4mm (Smallest) Baroque and early Classical and Romantic period flutes.

  • 7.0mm (Smaller) Romantic period flutes, smallest holes on Rudall-Rose.

  • 8.0mm (Small) London-based flutemakers manufactured many of their flutes like this, even after Nicholson’s revolution.

  • 9.0mm (Medium) Nicholson Flute. The third photo below shows a Rudall-Rose flute and a T. Prowse flute that have almost identically-sized holes. Prowse was authorized to stamp his “C. Nicholson’s Improved” and it’s my understanding these measurements represent the large-holed version of his flutes that other maker’s copied.

  • 9.6-10mm (Large) Pratten Flutes.

There are of course exceptions to the above specs if we are talking about antique flutes, and the water is muddied by the fact that many English flutes fall somewhere between the above delineations (what do we call a flute with a #4 hole of 7.5mm or 8.5?), but at least this is a standardized nomenclature that we can employ to compare one flute to another with some level of precision.

We use this system to describe our own flutes, and on our price list the 8.0 is referred to as Small, the 9.0 mm is Medium, and the 9.6 is Large (we realize that a Baroque musician might call the 6.0mm “normal’ and the 9.0mm “gigantic.”) We don’t currently make a flute with anything smaller than the 8.0 above, as most of our customers are playing traditional music and want the more “open” sound. I do own many antique flutes (including two by Rudall-Rose) with smaller holes that I think have a beautiful tone.

If you want to know the specific measurements of your own flute, you can buy a plastic vernier caliper (plastic is good because you won’t risk scratching the flute) for about $20. This comes in handy if you want to make precise measurements.

I hope that this system of sizing will aid anyone who wants to compare flutes and gain some insight into the way that hole-size effects tone.



(Pictured above: French, 6.5mm, American, 7.0mm, and Rudall-Rose and T. Prowse, 9.0mm)

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