Playable soundswith the alphorn
The tonal range of the alphorn is the so-called "natural tone series" with a tonal range of 12 to 16 tones per alphorn, depending on the mood. Basically, the longer the alphorn, the more notes can be played!
The mood
The tuning or fundamental tone depends on the length of the horn. Short horns have a higher fundamental tone than longer ones. The length of the fundamental sound wave is therefore shorter than in a long horn. This means that the frequency is higher and a higher tone is produced.
The conical shape and the cup also have an influence on the mood. If you determine the resonance frequencies only for the conical tube, you do not get whole multiples of the fundamental frequency for the overtones, as is the case with an ideally thin tube (see experiments with a hose) with a constant diameter. There is a deviation from the natural tone series, other non-harmonic intervals arise. If you determine the resonance frequencies of the entire alphorn (with the cup), you get the harmonic natural tone series. This means that the cup corrects the inharmonic tone series to the harmonious natural tone series. This was measured by Rolphe Fehlmann in 1994.
The natural tone series
You can blow different sounds with the alphorn. Depending on how strongly you let your lips vibrate, a higher or deeper tone is created. The pitch of the sound depends on the frequency at which the lips vibrate. High frequency means high tone, low frequency means low tone. If you now look at the waves, at a higher frequency more wave crests and troughs arise in a certain time than at a lower frequency.
In the Alphorn there are pressure surges. The faster the lips vibrate, the more pressure surges occur and the higher the tone becomes. But not every frequency produces a nice sound. You can only play the tones of the natural tone series, which are the resonance frequencies of the alphorn.
This series begins with the lowest note, the fundamental note. A wave is created with two negative pressure antinodes at both ends and a pressure node in between. The next higher tone creates two pressure nodes. It continues like this, each next note has one more pressure node than the previous one. This means that the frequency of a tone is a multiple of the frequency of the fundamental tone. This tone sequence is called the harmonic natural tone series.
If you play the natural tone series, you start with the fundamental tone, the second tone is an octave higher, the next a fifth, then a fourth, etc. These intervals are the ratios of the frequencies of two different high tones. When you play this series of natural tones, you can immediately hear that some of the tones sound unusual.
The 7th, 11th (also called Alphornfa in the Alphorn) and 13th natural tone seem a little too high or too low to us. This has to do with the fact that our ears are used to the temperate mood. Here an octave is divided into 12 identical semitone intervals. This means that only the octave is a pure interval. All other intervals have a small deviation from the natural frequency.
This deviation is particularly noticeable when you compare the 7th, 11th or 13th natural tone of the alphorn with the corresponding tempered tones of a piano. The tones are slightly different.
The unmistakable Alphorn company
The sound of the alphorn is a purely natural instrument. In this capacity, the natural tones come into their own in a wonderful form. The very special sound is the alphorn fa. It is the 11th tone in the natural tone series (see below). The expression “Fa” comes from the language scale Do – Re – Mi – Fa – So – La – Si – Do. It therefore refers to the 4th tone. The 4th note in the C major scale is F. However, F cannot be played on the alphorn. If you want to play the note between E (third) and G (fifth), you will hear an “intermediate note” that lies exactly between E and G. This intermediate tone is called “Fa” on the alphorn. If you narrow down the middle between E and G more precisely, you can see that the alphorn Fa lies between the F (fourth) and the F sharp (tritone). In other words: the Alphorn Fa is neither an F nor an F sharp.
The alphorn fa has a special appeal. In the past, the Alphorn Fa was long outlawed by the Swiss Yodeling Association, or at least described as “an undesirable sound” (sonus non gratus). The Alphorn FA was consistently disapproved of at the Alphorn competitions in Switzerland. Alfred Leonz Gassmann (see below) used both the alphorn Fa and the B flat in his compositions. In doing so, he gave the alphorn tunes a new expressiveness that, in the right form, creates a special appeal. Today there will soon be hardly any compositions that do not include the alphorn fa.
Anyone who has had basic training in brass music will have a hard time with the unusual alphorn fa. The reason is that this alphorn fa “falls” from the diatonic tone. It's worth trying for a longer period of time: Don't play the alphorn for a long time, but "only" the trumpet, flugelhorn or trombone. Then switch to the alphorn and play the natural scale. You will find that it is extremely difficult for you once you have got used to the melodious alphorn fa with your lips and your hearing again. Many listeners - especially from brass music circles - even think that the alphorn player plays the wrong note. Anyone who plays the alphorn will soon know what expressive power this alphorn instrument contains. In the vocabulary of alphorn players, one consciously speaks of the “Alphorn-Fa”. They have almost made this natural tone their own.