Harmony of sounds is a vocal event and is based on the frequency equivalence and compatibility among sounds as a content and endo-linguistic issue associated with the phonological structure of agglutinative languages. Melody, on the other hand, is the phenomenon in which the sounds in the sound envelope occur as a result of the succession and concentration of the sounds in a word with measurable dimensions that are compatible with each other. Harmony of sounds, which occurs in the form of physiological-acoustic harmony and reconciliation of sounds, has the characteristic of a “law” that will create a typology for Turkish and classify the interrelated sounds in the same layer according to their phonological characteristics. Harmony of sounds has the qualities of having “insicam”, which means having harmony between sounds; “tecanüs”, which means having the elements of the same gender; “teellüf “, which means consistency and cohesion; and “selaset” which means fluency. Phonological Criteria, which determine the natural boundaries of sounds in harmony with sounds, are the formant frequencies of vowel letters, which are “triggering sounds” enabling sounds to be integrated, used in the synthesis of words, and change. The formant frequencies, which create high amplitude and low-frequency vibrations between sounds, change their harmonic values. Depending on the magnitude of the harmonic value, the affected sounds match the characteristics of the trigger sound (i.e., the vowel) and achieve sound harmony more easily and powerfully. The Harmonic Mean “HM”, which is one of the Pythagorean Proportions and is used in mathematics frequently, can be used as an analysis processor to identify the harmonious middle between sounds and show the effect of the frequency values of the vowels in the trigger sound position on the sounds. The sounds are discussed according to dependent and independent variables in the present study, which had the design of a local study based on combining the sounds in the word in precise ratios and matching the affected sounds with the characteristic of the triggering vowel, and evaluations are made according to the Group Theory and the Analogical Principles regarding sound harmony. It was determined in sample applications that sound harmony fell in line with the harmonic average of the formant frequency values of the sounds in a word, and the harmony was strong or weak as the trigger sound (i.e., the vowel) approached the formant frequency values. Also, a new classification attempt was made in the present study regarding the harmony of sounds in Turkish by making use of syllogism, analogy, and the Group Theory (i.e., the Symmetric Theory), the information and nomenclature were reviewed by evaluating the harmony of sounds, and the accurate and consistent forms of usages that had term-definition incompatibility were uncovered. In the study, intermediate words, intermediate sentences, term equivalents and the information to be emphasised are shown in quotation marks.

Harmony of sounds, harmonic mean, formant frequency, triggering vowel, symmetry theory.