Why do our ears dislike clear sinus curve from an electronic tone generator?
Why does the tone “C” played on a guitar have the same frequency as the tone “C” played on a piano, and we are still able to immediately tell which musical instrument the player used?
Let’s look closer at how human auditory apparatus perceives music. Let’s talk about what is decisive, what is essential and what is irrelevant.
A tone is the essential building block of music. It is created by regular vibrations of musical instruments or vocal cords. A tone has a certain pitch, duration, intensity, and timbre, which will be given the greatest attention.
Timber of a tone depends on the spectral composition of sound, shape of vibrations, or the ratio of amplitudes of overtones. It all depends on the musical instrument that makes the tone.
Individual tones differ in pitch (frequencies). However, the human ear does not perceive the difference of frequencies as a machine does, it distinguishes them according to their share. A tone with double frequency sounds to the human ear one octave higher. In music for the sake of clarity, individual tones are given letters c, d, e, f, g, a, h.
A chord (from the Italian word accordo, which means harmony or consent) is three or more simultaneous sounds of different tones arranged according to a particular system. A good example might be pressing three or more keys simultaneously on the piano or the sound of three or more guitar strings at the same time. Each chord has its name and sign, which are derived from the tones of which the chord is composed, and the distance between the tones.
Chords are divided into several groups according to their structure and the number of tones.
Music is an organised connection of tones, chords at theirs rhythmic division. Music is art, it can bring up feelings such as joy, sadness or euphoria. We may want to dance, relax etc.
There are four basic building blocks of the traditional conception of music:
– rhythm (music of indigenous tribes played on drums, etc.)
– melody (folk song sang without being accompanied by musical instruments, singing of birds)
– harmony (chords played on a guitar or piano without singing)
– timbre (ie the “hue” of the sound and all sounds and noise around us)
Music is always the resultant combination of these four elements in different ratios, variations and combinations. From the aesthetic point of view, perfect music is a balanced combination of all four elements and each element is interesting, imaginative and self-contained.
Human hearing is not a machine
Overtone (also called aliquot tone) sounds together with a fundamental tone (the word aliquot means corresponding part or proportionate.) There is usually a series of overtones in the proximity of every fundamental tone. The intensity of overtones determines the characteristic timbre of the sound. We are able to recognize which musical instrument we are hearing due to hearing overtones. For example, instruments with sharper sound (trumpet, trombone) have stronger odd overtones (first, third, etc.), while even overtones give the sound warmth and softness.
Origin of overtones
A tone is created by regularly vibrating part of a musical instrument (string, guitar body, vocal cords etc.). Musical instruments never vibrate only on fundamental tone frequency. They are usually still shaking in the integer multiples of the base frequency. These multiples are the frequency values of overtones. The first overtone therefore has twice higher frequency than the fundamental tone, the second overtone triple etc. The overtones create a series in which the intervals between the individual tones are smaller and smaller. This is due to the fact that the human ear perceives the pitch of sounds logarithmically and every other octave has double frequency. The frequency of octaves therefore grows exponentially in powers, whereas frequencies of overtones grow only linearly in multiples. Specific timbre of tones of each instrument depends on the varying intensity of individual overtones in its sound.
Overtones are part of every tone in all types of music
Frequency relationships between overtones form the basis of Meantone Tuning, which was used in European music until the eighteenth century. Since this tuning complicated implementation of harmoniously complex music, European music replaced it with Equal Temperament Tuning, which is based on mathematical division of octave into twelve identical parts. This enabled composing large and complex pieces of music, easier transposition and easier interplay of individual instruments. However, some musicians today are coming back to others types of tuning. Their reasons are the desire for an experiment or the belief that by transition to equal temperament tuning the music has lost something very important and that the opportunities gained are not worth the loss.
The effect of missing fundamental tone
The effect of missing fundamental tone is an interesting psychoacoustic phenomenon that deals with the fact that human ear is used to identifying frequency, that is, the pitch of the tone using overtones contained in it. However, it was found that one can still hear the same tone even if the fundamental tone is removed from the signal and only overtones remain. Even if the first overtone is removed, one can still hear the same fundamental tone, although the course of the signal is, of course, very different.
Similarly, this principle can be used in choir singing. When the singers are precisely tuned into the tones that could be overtones of a certain fundamental tone, this tone will be audible without being acoustically present. They can actually “sing” tones up to one octave lower than the range of any member of the choir.
This phenomenon is called intermodulation distortion and it arises as a result of nonlinearity of the human ear (nonlinearity of the transfer of hydrodynamic processes into nerve impulses in the ear canal).
Overtone singing, also called throat singing or harmonic singing, is a special type of singing based on conscious reinforcement of overtones by fine work with the resonant space in the mouth and the position of the tongue. It is actually a technique of using two voices; we can hear the fundamental tone together with the overtone tone, which is corresponding interval higher.
History and traditional forms
The technique of overtone singing evolved exclusively in non-European musical cultures, especially in Tuva and in Tibet. In Tibet, harmonic singing is part of meditation of the monks. Overtone singing, or the sound of aliquot tones, is neither the intent nor the goal, but rather a by-product of meditation. Overtones are created because people sing very slowly and deeply when they meditate. In Tuva, overtone singing is part of traditional culture (it is called Chöömej), and especially shepherds use this technique of singing.
In Europe harmonic singing was not used until the 20th century. Increasing interest of classically educated European musicians and musical composers in non-European musical cultures was responsible for the discovery of this technique. The first European to learn it was Karlheinz Stockhausen. In the seventies, this style of singing was discovered by the broad music audience. The New age movement was mainly responsible for its gain in popularity. Since then ovetone singing has been done by many people around the world and the new epoch for overtone singing has begun. It is now developing beyond its culture of origin into various new forms.
Performers who use overtone singing:
- Huun-Huur-Tu (Tuva)
- Hosoo&Transmongolia (Mongolsko)
- Okna Tsahan Zam (Kalmycko)
- Tyva Kyzy (Daughters of Tuva)
- Yat-Kha (Tuva)
- David Hykes (Francie)
- Michael Vetter (Německo)
- Jill Purce (Velká Británie)
- Christian Bollmann
- Stimmhorn (Christian Zehnder) (Švýcarsko)
- Sarah Hopkins (Austrálie)
- Jim Cole & Spectral Voices (USA)
- Steve Sklar (USA)
- Paul Pena (USA)
- Wolfgang Saus (Německo)
- Stuart Hinds (USA)