Music is language. Not necessarily in word, but in tone, mode, and forms. Yodeling, and its various forms, probably originated not in music but as a form of communicating information by sound. Later it was incorporated into ethnic songs and music.
Most are familiar with the yodel of the commercial for menthol cough drops in the Alps, or in older country and western singers, such as Jimmie Rogers. But few are aware that the 'yodel' is only one expression of a wider form and expression of voice.
According to Wikipedia, yodeling is a "form of singing which involves repeated changes of pitch during a single note. The singer quickly switches between the low-pitch chest register (or "chest voice") and the high-pitch head register or falsetto." The most familiar to American listeners is the yodel from the Alps, where the yodel was used by herders to call their livestock or to locate their location to others. Yodeling and whistles were also used by some indigenous African hunters to communicate location of game and themselves. In almost all cases, this form of communication became embedded in their traditional music, especially during rituals.
Other forms of yodeling are found in many ethnic folk music: Persian, Bulgarian, Arabic, Flamenco, Georgian, and African. The differences can be profound or subtle. In contrast to the wide variation in scale and tone of yodel of the Alps, another form is common in the former Persian countries. Any person that has listened to the morning or evening Islamic call to prayer never forgets the eerie yet entrancing trills that float on the air.
"In Persian classical music, singers frequently use tahrir ("tremolo" in English), a yodeling technique that oscillates on neighbor tones. It is similar to the Swiss yodel, and is used as an ornament or trill in phrases which have long syllables, and usually falls at the end of a phrase. Tahrir is also prevalent in Azerbaijani, Bulgarian, Macedonian, Turkish, Armenian, Afghan, and Central Asian musical traditions, and to a lesser extent in Pakistani and some Indian music."- WikipediaVoices using micro-intervals and polyphony can still be heard in ethnic and folk music of some European countries. Microtonal music can refer to all music which contains intervals smaller than the conventional contemporary Western semitone. Think of mini-yodeling.
My personal favorite is flamenco, which is rooted in the Andalusian gypsies and ancient Moorish influence. The cante flamenco, or 'flamenco song', often uses micro-intervals and polyphony to express passion. 'Cante jondo' is considered the purist form, the heart and soul, of flamenco voice; it is the 'deep song', expressing death, anguish, despair, or religious sentiments. Cante jondo is often accompanied by flamenco guitar, but also sung to the percussion of hand claps and stamping feet or a cappella (without instrumental accompaniment).
Flamenco singer Camaron De La Isla championed the traditional style of cante jondo, as did others that followed him (such as Enrique Morente, who passed away in 2010). You can hear a podcast examining Camaron's career and flamenco voice by following this link (Camaron De La Isla: The Voice Of Flamenco).
Variations of a yodel my be heard in other traditional music. Mugham is a style of music and voice of the Azerbaijani people in the Caucus mountains and nearby. This, too, has roots in old Persian music style.
"The full throated yodeling technique of the Kavkaz Azerbaijani ashikh lends an extraordinary power to the elegant and folksy melodies they employ while accompanying themselves on the saz, a long neck lute. When these two great and ancient musical traditions met and mixed, they gave birth to an extraordinary style of music that is evolving. To best appreciate mugham, it should be understood as a modern development of an ancient practice, which is the use of sound to induce a transformation of consciousness. Today this might be called trance music, but it would not be a good translation, because the word ’trance’ is associated with the hypnotic trance, whereas mugham offers an enhancement of consciousness, not a loss of consciousness of any degree.Another example of voice that incorporates a type of yodeling is the folk music of Bulgaria, exemplified by the wonderful Bulgarian State Television Female Vocal Choir. They use diaphonic singing and distinctive timbre, as well as modal scales and dissonant harmonies, usually unaccompanied by instruments. Their voices are melodic and captivating. If you listen to the song embedded below, you can detect the micro-intervals of voice that, again, is a type of yodeling.
Melodies used to attain ’trance’ states are relatively simple and repetitive, and versions of this can be found throughout the Middle East, Africa and Central Asia among the more nomadic tribes. In the cities, the more ’classical’ styles of music evolved, such as dastgah and mugham. In this sense, mugham is modern. It is as evolved in its form as the great classics of European music are in their form." - Visions of Azerbaijani
So now you know that yodeling is not relegated to the Alps or American country singers. You might even be enchanted by the various forms in other world music like I am.