From the beginning to the end of the tonic, from low to high (called rising tone), or from high to low (called falling tone), the tones are arranged in the mode step by step, which is called scale.
For example, CDEFGAB in the scale, from C to D, is a key and an octave from C4 to C5.
A series of tones arranged in the order of whole, semitone and other intervals.
The basic scale is C major scale, and all the keys are used when playing on the piano. One key up refers to the pitch increase from the white key to the next white key, such as C4 to D4. A half key up corresponds to the black keys in the piano, which is called semitone, such as C4 to #C4.
Extended data
tone control
The so-called tuning is to artificially change the proportion of high-frequency and low-frequency components in the signal to satisfy the listener's hobby, render a certain atmosphere, achieve a certain effect, or make up for the shortage of speaker system and sound in the playing place.
This control process does not actually change the tone (frequency) of various sounds in the program. The so-called "regulation" is just a conventional name, which is actually "high and low control" or "tuning". Most hi-fi amplifiers are equipped with tone controllers. However, in order to ensure the quality of signal transmission, tone control is unnecessary.
A good tuning control circuit should have enough adjustment range of high and low notes, but at the same time, it is required that the amplitude of midrange signal (usually 1000 Hz) will not change obviously during the whole adjustment process of high and low notes from the strongest to the weakest, so as to ensure that the volume is basically unchanged.
Tone control circuits can be roughly divided into attenuation type and negative feedback type. The adjustable range of the attenuation tuning control circuit can be wider, but the midrange level is greatly attenuated, and the impedance of the whole circuit also changes during the adjustment process.
So the noise and distortion are greater. The noise and distortion of negative feedback tuning control circuit are small, but the adjustment range is limited by the maximum negative feedback, so it is often used in combination with input attenuation in practical circuits to become mixed attenuation negative feedback.
Baidu encyclopedia-tone
Baidu Encyclopedia-Scale