April 21, 2017

overtone singing

Tibetan monks



Overtone singing, also known as overtone chanting, harmonic singing or throat singing, is a type of singing in which the singer manipulates the resonances (or formants) created as air travels from the lungs, past the vocal folds, and out of the lips to produce a melody.     

The harmonics (fundamental and overtones) of a sound wave made by the human voice can be selectively amplified by changing the shape of the resonant cavities of the mouth, larynx and pharynx. This resonant tuning allows singers to create apparently more than one pitch at the same time (the fundamental and a selected overtone), while actually generating only a single fundamental frequency with their vocal folds (links to samples below).

It is thought that the art of overtone singing originated from south western Mongolia in today's Khovd Province and Govi Altai region. Overtone singing is a technique and cultural or spiritual musical artform, developed in Mongolia, Southern Siberia, Central Asia, Tibet and in South Africa. It also is used to a lesser degree in Sardinia, the only ancient form of European overtone singing that is still practiced. Many theories exist that overtone singing once had a ritual and spiritual use in Kabbalistic ceremonies, Masonic lodges, mystery schools and Sufi practices.    

There are videos on YouTube of an amazing artist, Anna-Maria Hefele, performing overtone singing with SUPERSONUS in several productions (link below).       


overtone graphic representations



Overview of glissando exercises based on the harmonic series. 
Human proportion study by Albrecht Dürer (1471-1528).




The voice of overtone singing is characterized by a sharp formant centered at nF0, as can be seen in Figs. 1 and 2.   







The Kargyraa throat-singing style employs a characteristic low growling tone, produced by other soft tissues in the vocal tract vibrating sympathetically an octave below the frequency of the vocal folds. This, among other things, gives the singer more harmonics to work with in a given range of frequencies, for reasons that should become somewhat clearer later on.




The muscle utilized for throat-singing is the superior pharyngeal constrictor muscle, in the pharynx. It is the highest located muscle of the three pharyngeal constrictors. The muscle is a quadrilateral muscle, thinner and paler than the inferior pharyngeal constrictor muscle and middle pharyngeal constrictor muscle.   







Performer Christian Zehnder exposes his singing to X-Rays. Image made with the Dept. of Radiology at the CHUV Lausanne (link below). Extract from the material of INLAND, a film by Pierre-Yves Borgeaud with Stimmhorn (2002). Production: SF / SSR idée Suisse, momentum production.    

Performer Christian Zehnder







The low tone, or vocal subtone, is caused by the oscillation of tissues that lie above the vocal folds. We use the vocal folds for everyday speech and song. The tissues above these actual focal folds are known as the false vocal folds, and you can see them on the diagram below, which is a cross sectional view of the larynx.   
When the actual vocal folds are set into periodic vibration with a highly tensed glottis, the false vocal folds are pushed together and slightly upward toward the back of the throat. These slimy little flesh curtains are set into motion to produce a subtone, they look and feel like puckering lips.

When set into motion, these false vocal folds vibrate most optimally, with maximum amplitude and consistency, at exactly one half the rate of vibration of the actual vocal folds. For example, if actual vocal folds are singing an A 440 Hz and you set your false vocal folds into optimal vibration, you will produce a strong subtone of 220 Hz simultaneously with the 440 Hz tone of your actual vocal folds. Thus, producing two distinct oscillations spaced one perfect octave apart.


Almost any overtone-singing style is executed using one of three voices. The “voices” are more than just three differing vocal timbres. The first voice, the “neutral”or “natural”voice, uses no more laryngeal tension than is necessary for speech. Second, the “throat” voice (known as the khoomeivoice in Tuva and neighboring regions in Central Asia), uses an immeasurable but clearly audible amount of increased tension in the larynx. Technically, the throat voice is made by increasing the length of the “closed phase” in each open-and-close cycle of a periodic frequency. The throat voice is not unique to Central Asia, and it can be heard in parts of Central and North Africa and among blues and rock vocalists such as Howlin’ Wolf and Captain Beefheart. Third, there is the “subtone” voice, which I think of as a kind of extension of the throat voice, but with prominent, and downright unmissable, sympathetic vibration of the false vocal folds and, in many singers, other surrounding tissues of the vocal tract.

The “voices” 

         
         
           

Net links:        
Anna-Maria Hefele               
      
YouTube links:      
         
throat-singing
Christian Zehnder         
Anna-Maria Hefele          

           
          

Styrous® ~ Friday, April 21, 2017 


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