(1) Pitch

Pitch is an attribute of hearing, it is a psychological quantity, and the unit is beauty (mel). The pitch of pure tone depends on the frequency of sound vibration. The correlation between pure tone pitch and frequency can be directly obtained by psychophysical method, that is, the pitch is divided into grades from low to high in the audible range, and a pitch scale is made.

Figure 7-5 is a pitch scale, with the abscissa indicating frequency and the ordinate indicating the corresponding pitch, showing the functional relationship between pitch and frequency. Two methods can be used to compile the pitch scale: dichotomy and multi-division.

the dichotomy is to let the subjects adjust the pitch of a variable pure tone to half of the standard pitch and get the corresponding frequency. In order to facilitate the establishment of the pitch scale, the pitch of 4 dB and 1 Hz pure tone is generally designated as 1 US.

The multi-division method (taking the quartering method as an example here) is to give the subject a high-frequency sound S and a low-frequency sound Ss, and ask him to call out three sounds between them, so that the pitch distance of each adjacent two sounds is equal, that is, S1-S2 = S3-S4 = S4-S5.

(2) Loudness

Loudness is also an auditory attribute, which is the subjective quantity of human ear's response to sound intensity. The unit is sone),1 and one song represents the loudness of 4 decibels and 1 Hz pure tone.

The method of making loudness scale is similar to that of pitch scale, so I won't say much here. However, loudness is not only related to sound pressure (physical intensity of sound), but also related to audio. For example, the sound pressure level of two sounds with frequencies of 1 Hz and 1 Hz is 4 dB, but the loudness is very different. The sound with frequencies of 1 Hz is much louder than the sound with frequencies of 1 Hz.

we usually use the equal-loudness contour to express the relationship among lightness, sound intensity and audio, that is, the curve of sound pressure levels of pure tones with the same loudness level, as shown in Figure 7-6. The loudness perception of sounds of various frequencies on each curve in the figure is equal, so it is called an equal sound curve. We can use the adjustment method to make an equal sound curve. First, we select a pure tone with a certain intensity of 1 Hz as the standard stimulus, and use sounds with different frequencies as the comparative stimulus. The listener adjusts the intensity of the comparative stimulus until it is equal to the loudness feeling of the standard stimulus.

source: Guo Xiuyan, revised by Yang Zhiliang. Experimental Psychology, People's Education Press, 219.