A piano piece entitled "4' 33''", written by the American composer John Cage (1912-1992), could be considered to be the most distinctive work in the history of Western music. In the performance, the pianist comes out in front of the audience in a concert hall and sits at the piano. When four minutes and thirty-three seconds have passed, the pianist rises, bows to the audience and leaves, having not played a single note. Cage has explained the creation of such a work of music by the need to draw listeners' attention to the sound background filling our environment, which usually goes unnoticed. Indeed, the silence in a concert hall is never absolute, even when the instruments or voices have stopped. Somebody might whisper, somebody else might cough, a humming bee might have entered the hall, etc.

Cage's work again poses the question for scholars of music: how should the limits of music be defined? It can be said without exaggeration that this question has been a common topic throughout the history of mankind, but it had never reached such an extreme as in the performance of Cage's work in 1952. Many passionate discussions have been held in the history of the Church about what kind of music can be used at religious services and what kind of music is unsuitable for this purpose. Even now, some confessions do not allow instrumental music inside the walls of their churches. Musical education is conservative by nature; if we consider the history of twentieth-century music, we can see that some genres (jazz, rock) have been accepted as suitable for teaching only long after these genres have commonly been accepted by the public.

A modern definition of music should, therefore, be very broad, in order to take into account all the cultural differences in time and space. If we really want to include in this definition both the Western avant-garde and modernism of the 20th century and the ethnic music of native peoples living in far-off corners of the world, we can only say that music is something that is composed of sounds arranged by human beings. This definition involves two preconditions, without which we cannot talk about music. These preconditions are the presence of sounds and the presence of humans. No music can exist without the participation of a human being, as a creator or as an interpreter or both (as is common in traditional cultures). What's more, no music can exist without sounds. It is true that this assertion has now and then been questioned in musical theory. Since Ancient Greece it has been possible to follow the European tradition of thought concerning music, according to which "ordinary" music, consisting of sounds, is only a part of a much more general music that fills the Universe, the "music of the spheres". The Greeks may possibly have thought that similarly to "ordinary" music, where sounds are made by vibrating bodies, such as the strings of an instrument, or the skin of a drum, the planets in the Universe could make sounds too. But since human beings are not perfect by nature, they have not been given the ability to hear the sounds made by the planets.

Proceeding from this we could ask: which are the sounds, within the limits of human hearing and allowed by the laws of physics, which can be used to make music? As mentioned above, something has to vibrate to make a sound. In addition to strings and membranes, a column of air in a closed space can vibrate, as with wind instruments and the human voice, or a solid as a whole can vibrate, as in case of the cymbals or the triangle. If the vibration is regular in time, hearing gives it a certain pitch. The pitch of a sound is, in turn, connected with the number of repeated wave periods in a certain time unit, called frequency and measured in hertz (Hz).

The human ear is able to hear sounds within the frequency of 20 to 20 000 Hz. The lower limit of hearing is only slightly lower than the lowest key of the piano - the la of the subcontraoctave. In other words, there would be no sense in extending the keyboard still more to the lower side - human beings would simply not hear the sounds made by depressing these additional keys. The upper limit of hearing offers a more complicated problem. Only young people are able to hear high sounds. Beginning from about the age of twenty years, the upper limit of hearing begins to decline. The speed of this decline is about one Hz a day. A simple calculation shows that compared with young people, the hearing of a 50-year-old person has considerably deteriorated regarding the upper limit. This is not a pathological phenomenon, but rather a norm, characterising almost all people regardless of gender, nationality and race. Consequently, in making music, there is no sense, and it is even impossible, to use the whole frequency interval accessible to young people. Some additional limits to the frequency interval are partly determined by other characteristics, e.g., the sharpness of hearing is most acute between 2 000 and 5 000 Hz. There is reason to believe that musicians all over the world have intuitively taken this factor into consideration when choosing their sounds.

What is the relationship between the natural objective requisites, enabling the emergence of music, which we attempted to outline above, and the cultural superstructure based on them? Compared with the first half of the 20th century, the second half of the century offered a wide range of answers to this question. Western European thought of the mid-20th century is strongly marked by the breakdown and the final destruction of a "Europocentric" worldview. Between the two world wars, music psychologists were primarily interested in the possibility of the objective appraisal of musical abilities of human beings, the natural aim of which was the ranking of individuals, as well as of whole cultures of music. The treatments of music of that time silently revealed, and occasionally even clearly stated, the conviction that Western music was better and hierarchically of a higher rank than the music of other nations, and that among the types of Western music, classical music was, in its turn, higher ranking than popular music. During the following fifty years, the pendulum has reached the other extreme, at least concerning ethnomusicologists. The key words of modern musical studies are multiculturality and cultural specificity. The number of those scholars of music who would publicly dare to speak about music universals, i.e. the features of music that would characterise all music cultures of the world and would not be specific to a certain culture under observation, is small.

It is true that during recent excavations at various locations around the world, instruments or their fragments have been found, which are thousands of years old. The study of these instruments seems to indicate the need to reduce again the cultural specific approach to music studies. Based on recent finds, we have reason to assume that such categories as the equivalence of octave and the diatonic scale (or its elements), which characterise the sounds of music, are not necessarily strange to the music cultures of the majority of nationalities of the world. The equivalence of octave means that all sounds of the same names - all dos, res and mis, etc., are so similar to each other that it is not too important in which octave, or how low or high their exact position is. The effect of the equivalence of octave is best characterised by the possibility of the singing of the same tune by both male and female voices, since female voices are about one octave higher than male voices. The diatonic sound scale is nothing less than the same do-re-mi-fa-sol-la-ti-do, which we all learned at school. It is a little strange to think that the tunes played on a flute in China, several thousands years ago, could well have consisted mostly of the same musical intervals that we use to make music in Europe now.

The most ancient layer of Estonian music is the runosong, the age of which may not be much younger than that of the flutes or glockenspiels excavated in China. The tradition of the runosong can also be examined by using music universals. When talking about the melodic structure of runosongs, runosongs can be called, using the specification of the American ethnomusicologist Bruno Nettl (1930), the "simplest" musical style of the world. Such music is characterised by unison melody, moving within the third or fourth, its notes being of almost similar length. In the Setu tradition, located in south-east Estonia and mostly following the Greek Orthodox confession, polyphonic singing is used, with scales different from those in the rest of the Estonian territory. The Setu scale alternates a semitone and a whole tone plus a semitone, which, again, is not an exclusively location-specific phenomenon. For example, French composer Oliver Messiaen (1908-1992) loved to use such scales, with their strong constructive potential, which differs from traditional diatonic ones.

Jaan Ross (1957), music professor, researched among other things the structure of folk songs of the Baltic region countries and the peculiarities of the perception of sound pitch and hearing illusions.