1.The subjective sense of frequency domain
The most important subjective feeling in the frequency domain is the tone. The tone, like the loudness, is also a subjective psychological amount of the hearing. It is the attribute of the hearing judgment.
The difference between the tones in psychology and the scales in music is that the former is pure tone, while the latter is the tone of compound sounds like music. The tone of compound voice is not only the frequency resolution, but also the function of the auditory nervous system, which is affected by the listening experience and learning of the listeners.
2.The subjective sense of the time domain
If the voice duration is more than about 300ms, then the increase of the time length of the voice will not change the threshold of hearing. The sense of pitch is also related to the duration of the sound. When the duration of the sound is very short, the tone is not audible, only to hear "click". The duration of the sound is longer so that the tone can be felt. Only when the voice lasts for more than a few milliseconds, can the tone of the feeling be stabilized.
Another subjective feature of time domain is echo.
3.The subjective sense of space domain
The ear of the human ear has obvious advantages over the single ear sound, which has high sensitivity, low hearing valve, a sense of direction to the sound source, and has a strong anti-interference ability. In stereophonic conditions, the sense of space obtained by speakers and stereo headphones is different. The sound that the former hears seems to be in the surrounding environment, and the latter is heard in the interior of the head. In order to distinguish the two spatial senses, the former is called orientation, and the latter is called orientation.
4.Weber's law of hearing
Webb's law shows that the subjective perception of human ear is proportional to the logarithm of objective stimulus. When the sound is smaller and the amplitude of sound wave is increased, the volume of the subjective sensation of the human ear is larger. When the sound intensity is larger and the same sound wave amplitude is increased, the volume of the subjective sensation of the human ear is smaller.
According to the hearing characteristics of the human ear, the index type potentiometer is used as the volume controller when the volume control circuit is designed, so that the volume is linearly increased when the turn handle of the potentiometer is uniformly rotated.
5.Ohm's law of hearing
The famous scientist, ohm, discovered Ohm's law in electricity, and he found Ohm's law of hearing in the human ear. This law reveals that the hearing of the human ear is only related to the frequency and intensity of the various sounds in the sound, but is independent of the phase between the various sounds. According to this rule, the process of recording and replaying in the sound system can not take into account the phase relation of each sound in complex voice.
The human ear is a frequency analyzer which can separate the Homophones in the compound. The human ear has a high resolution to the frequency. At this point, the human ear has a higher resolution than the eye, and the human eye can not see the various color light components in the white light.
Other sounds in the environment reduce the hearing of a listeners to a certain voice, which is called masking. When the intensity of a sound is far greater than the other, when the two sounds exist at a certain extent, one can only hear the sound of the sound, and the other sound is not aware of the existence of the sound. The masking volume is related to the sound pressure of the masking sound, and the sound pressure level of the masking sound increases, and the masking volume increases accordingly. In addition, the masking range of low frequency sound is larger than that of high frequency sound.
This hearing characteristic of human ears provides important inspiration for designing noise reduction circuits. On tape, there is such a listening experience that when the music is constantly changing and the sound is big, we do not hear the background noise of the tape, but when the music program ends (the blank tape), it can feel the "hissing" of the tape. Noise exists.
In order to reduce the influence of noise on the sound of the program, the concept of signal to noise ratio (SN) is proposed, which means that the intensity of the signal is larger than the noise intensity so that the sound will not feel the presence of noise. Some noise reduction systems are designed based on the principle of masking effect.
The basic principle of the binaural effect is this: if the sound comes from the front of the speaker, the sound source goes to the left and right ears at the same time, so that the sound wave reaches the left and right ear (phase difference) and the tone difference is zero, and the sound comes from the front of the listers, not on one side. When sound intensity is different, the distance between the source and the listens can be felt.
The experiments show that when the two sound sources are simultaneously sound, the hearing is different according to the time delay of one sound source and the other, and can be divided into three cases.
(1) when the time delay of one sound source and another source in two sound sources is within 5 to 35mS, it is as if the two sound sources merge into one, and the listers can only feel the existence and direction of the preceding sound source and do not feel the existence of another sound source.
(2) if a sound source delays another source 30 to 50mS, two sound sources can be sensed, but the direction is still determined by the precursor.
(3) if the time delay of one sound source is greater than the other sound source is 50mS, it can feel the existence of two sound sources at the same time, the direction is determined by the various sound sources, and the lagging sound is a clear echo.
Haas effect is one of the bases of stereo system orientation.
9.De Poe effect
The de Poe effect is another basis for stereotactic system orientation. The experiment of de Poe effect is to place two sound boxes on the left and right sound channels. The listens listen on the symmetrical line of the two speakers and feed two different signals to the two speakers, and the following conclusions can be obtained.
(1) if the two sound boxes are fed in the same signal, that is, the intensity difference Delta L = 0, the time difference delta T = 0, only one sound is sensed at this time and from the symmetrical line of the two sound boxes.
(2) if the intensity difference between the two speakers is not 0, the sound sense sound is biased toward a louder sound box, if the intensity difference Delta L is greater than or equal to 15dB, and the sound is completely from the louder sound box at this time.
(3) if the intensity gradation Delta L = 0, but the time difference between the two speakers is not 0, the T will move towards the first speaker. If the time difference delta T is greater than or equal to 3MS, the sound will come from the direction of the first speaker.
The Lloyd effect is a psychoacoustical effect in the stereo range. The Lloyd effect reveals that if the delayed signal and the reverse phase are superimposed on the direct signal, a clear sense of space is created. The sound seems to come from all sides, and the listers are in the band.
The single channel recording and playing system uses a microphone recording on a track, using an amplifier and a loudspeaker on the sound, so the replayed sound source is a point source, as the listens listen to the indoor Symphony through the keyhole on the door, which is the so-called keyhole effect.
In the bathroom, there is a personal feeling, the sound of the bathroom, the long and excessive reverberation time, which is called the bathroom effect in the acoustical description of the electroacoustic technology. When a low or intermediate frequency is exaggerated, there is resonance, frequency response is not smooth enough, 300Hz increases too much, and there will be bathroom effect.
The Doppler effect reveals the related sound characteristics of the moving sound: when there is relative motion between the sound source and the Lister, the tone of the sound determined by a certain frequency is changed. When the sound source approaches the listers, the tone is slightly higher, and when the source is gone, the tone of the frequency is slightly lower. The change in this frequency is called the Doppler shift. The intensity of the moving sound source at the same distance from the listens is greater than that of the non moving sound, and the intensity of the removed sound source is smaller, and the sound source is usually concentrated in the moving direction.
14．Li Kai Test
Li Kai test proves that when the phase of two sound sources is opposite, the sound and image can exceed two sources, and even jump to the rear of the sound.
The Li opening test also suggests that a wide range (angle, depth) sound image moving field can be obtained as long as the intensity and phase of the two sound source (left and right sound channel speakers) are properly controlled.
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