One major work with notations in the horn part that have confused many are the unusual stopped horn notations in the Academic Festival Overture of Brahms.
There are two big issues to consider in relation to this writing. The first is Brahms intentions as notated in the parts. In this case, the intention is clearly to write the parts in a manner that would leave them performable on the natural horn. But the second issue looms large in the background. How did players actually perform these parts in the period? They almost certainly performed the work on the valved horn in early performances.
The Academische Festouverture, Op. 80, was composed in 1880. In the following passage he requests certain notes to be performed Gestopft [stopped] at times in all four parts, this part being the first horn in C.
The first of the notes marked stopped would have been performed stopped on the natural horn in this context but would have been performed open on the valved horn absent any further instructions. This notation could be seen as an admission by Brahms that he realized his natural horn parts were in fact being performed virtually everywhere on the valved horn; the notation makes it clear however that these specific locations were intentional stopped effects that must be performed stopped even if performed on the valved horn.
[I also love that poco F dynamic marking; very Brahms. It is a dynamic between mf and F.]
A strong statement that Brahms may be making musically by his continuing to request natural horn in this passages is that to write for the natural horn was one of the most anti-Wagner stances he could have taken in relation to the charged musical climate of the period. Even if this was not his intention, he certainly gained something by writing for the natural horn, an almost intangible aspect but one that we, as horn players, are sensitive to. Horn writing conceived for the natural horn is inherently “hornistic;” it has a sound that sounds “right” for the horn, a sound that cannot be mistaken for a part written for another instrument in the same range as the horn. Being as well versed in the natural horn as Brahms was, this “sound” issue alone must have been highly significant.
Where does this leave us today? A conductor with limited knowledge of horn history and technique will probably expect that we play this passage as modern stopped horn, but this is actually not what is indicated or desired by Brahms. Brahms instead wants the type of light hand stopping used on the natural horn to produce those notes, which in a more modern notation we would call half-stopped. Furthermore, he I believe wants in this passage a mixture of open and stopped sounds just as if the part was being played on natural horns.
I have always performed this passage fully stopped, due to conductor expectations (we played this work dozens of time when I was in Nashville), but I have tried not to make the stopped notes too buzzy and harsh. It would be interesting to do the exact markings with the mixture of open and half stopped notes. You should do something other than play open horn at least.
For much more on Brahms and the natural horn please reference this post and the dissertation on the Brahms Horn Trio by Joshua Garrett, now posted as a download in Horn Matters, and also the article below in Horn Articles Online: