In Horn Technique Gunther Schuller wisely expands the discussion to include stopped horn and the related technique of half-stopped horn.
Beginners are often baffled by hand muting because of the transposition involved. In hand muting the hand closes the bell, preventing the air almost (but not quite) from coming out the bell. Because of the size of the throat of an average French horn bell, the point at which the average human hand almost blocks the air column is fairly far in the bell. This causes—in theory and in practice—a shorting of the tubing…. This in turn causes the raising of the pitch by approximately a half step, and the player must therefore transpose down a half tone to compensate for this. To be more exact, he must finger a not a half tone lower than the one desired.
Considerable confusion arises from the fact that another distantly related form of stopping the horn, called ‘half’ or ‘three-quarter muting’, is achieved by a somewhat similar hand manipulation, and results in the lowering of the pitch. I will return to this form of muting shortly.
I have seen this more frequently as half stopping or echo horn, such as is requested in the Dukas Villanelle, and in reality it is also what Brahms had in mind in his stopped passages, such as this one from his first symphony. Schuller continues to explain how it is critical in hand stopping to close the bell as completely as possible and that in general you must play stopped notes on the F horn for intonation. He continues,
As for half muting, it is a special effect, coming more and more into use with contemporary composers…. As the term implies, it is a means of half closing the bell, resulting in a half muted sound, with an unforced misty tone quality. It is a very unusual effect, giving the impression of a sound coming from a distance, a sort of echo effect. It can also be used for extreme pianissimo passages in very live acoustics.
After a long discussion of the acoustics behind hand stopping he also notes the following which is undoubtedly true. “I would like to suggest that the confusion among beginners regarding the two approaches to hand stopping arises from the simple fact that many of them experiment on their own and by chance find the ‘half muting’ method.”
As to hand stopping, Harry Berv in A Creative Approach to the French Horn has a very practical suggestion as to improving intonation.
When playing stopped-horn, the intonation tends to become sharp and, unless you know how to compensate for this by pulling the slides (which lengthens the tubing and lowers the pitch), you will not be able to play stopped-horn in tune.
In most instances, the pulling of valve slides for short, detached stopped tones is not required (the main tuning slide will take care of these notes). It is usually required, however, for prolonged passages. In this case, you will pull the slides approximately ½”, depending on the intonation of the horn and your natural tendency to play either sharp or flat. I say “approximately ½”” because it is impossible to generalize about the exact distance the slide should be pulled. The instrumentalist must find through his own practice and experimentation how far the slide should be pulled in order to achieve the correct intonation.
Those slides do move! He also notes that
It is generally easier to play in tune with a transposing mute than with hand-stopping, particularly in the lower register, because the airtightness required for stopped-horn playing is achieved immediately, and the mute is in the same position every time….
The metal transposing mute is excellent in place of the hand for muting in the low register. The sound is clearer and intonation much more respectable.
Speaking of transposing mutes, such as the one seen in the photo on the left, I recently had a conversation with someone who had tried one and did not feel it did much for them. I suspect however that they had either tried one that was not particularly good or one that did not fit their horn. For sure though as Berv says, “It is generally easier to play in tune with a transposing mute than with hand-stopping, particularly in the lower register.”
We will have yet more on stopping next week.