Musical Scale When a musical instrument produces sound

Musical Scale When a musical instrument produces sound of a single frequency , it is called a tone. When two tones are sounded together , their combination is called chord. Some combination produces an agreeable or pleasant effect called concord or consonance. While other combination produce disagreeable or unpleasant effect on ear called discard or dissonance. When two tones sounded together produced pleasant effect this combination called Harmony. If two tones sounded one after other , the combination is called as Melody. Pleasant effect is does not depending on the exact frequencies or difference in frequencies but only depending on the frequency ratio. The ratio of frequencies of the two tones is called musical interval. If the frequencies of three tones are n 1 , n 2 , n 3 then n 1/ n 2 is called musical interval of first and second tone.

n 2/ n 3 musical interval of second and third. n 1/ n 3 musical interval of first and third tones. Thus it is clear that musical interval of first and third tone is equal to the product of musical interval of first and second and that of second and third note. n 1/ n 3 = n 1/ n 2 * n 2/ n 3 Musical interval having different tones When several tones are produced in succession , their resultant effect appears to be pleasant to our ears. This combination of tones is called music. A series of several tones in increasing order to their frequencies are arrange in a series such that they have a definite musical interval and their resultant effect is pleasant to the ear , it is called as musical scale.

Characteristic of Diatomic Scale The diatomic scale has following to characteristics 1. In diatomic scale , the ratio of frequencies of first, third and fifth tone is 4: 5: 6. When they are sounded together , a very pleasant sound is produced they are called as harmonic triad. 2. In a diatomic scale , the three consecutive musical intervals are 9/8, 10/9 and 16/15 which are called as major tone , minor tone and semi tone. In a diatomic scale there are three major tones , two minor tones are two semi tones.

Defects of a diatomic scale • In diatomic scale we obtain very pleasant sound , but the major defects of this scale is that it is not useful for the musical instruments of definite keys. The reason is that on assuming the frequency of first tone C as the initial tone , the frequency of remaining tones are obtained in accordance with table but in music we need to change the tone again and again , therefore the musician experiences difficulty in this scale. That’s why in harmonium diatomic scale is not used.

Tempered Scale Shortcoming of diatomic scale is overcome by tempered scale. In this scale 1) Possibility of changing tonic , where large no. of notes slowly rising in pitch within the octave will be necessary. 2) Too many notes should not be included for the sake of practical convenience. 3) Dissonance should be avoided. Temperament is comprise between these demands. The adjusted scale is called tempered scale. Tempered scale having two types (i) Equal tone temperament (ii) Mean tone temperament In equal temperament scale between fundamental and octave ( Frequency ratio 1: 2 ) 11 other tones are so chosen that the musical interval of a tone with its preceding tone or tone thereafter is the same. Thus in this scale , the musical interval of the two successive tones is same and the other no. of tones is 13.

Let the frequency of fundamental be n , and then the frequency of octave should be 2 n. If the musical interval between the two successive tones is x , the frequencies of tones in this scale will be n, nx 1 , nx 2 , nx 3 , nx 4 , ……, nx 11 , nx 12 = 2 n x = 21/12 Thus in equal tempered scale musical interval between two successive tone is 21/12. Harmonium consisting of 8 white and 5 black keys. Out of which 8 white keys are for the frequencies of diatomic scale and black keys for the tempered scale. Using these keys musician obtained soft and sharp tone as desired. In mean tempered scale , the geometric mean of major and minor tones is taken as interval between successive notes.

Musical Instruments The musical instrument are divided in to he following three main categories 1. 2. 3. Stringed instrument Wind instruments Percussion instruments The Stringed instruments