Hearing Weber's law
Weber's law shows that the subjective feeling of the human ear is directly proportional to the logarithm of the objective stimulus. When the sound is small and the amplitude of the sound wave is increased, the subjective feeling volume of the human ear is increased by a large amount; when the sound intensity is large and the same sound wave amplitude is increased, the subjective feeling volume of the human ear is increased less.
According to the above listening characteristics of the human ear, an exponential potentiometer is required as a volume controller when designing the volume control circuit, so that the volume is linearly increased when the potentiometer is rotated uniformly.
Auditory Ohm's law
The famous scientist Ohm discovered the Ohm's law in electricity, and he also discovered the Ohm's law of the human ear. This law reveals that the hearing of the human ear is only related to the frequency and intensity of each part of the sound. The phase between the tones is independent. According to this law, the control of the recording, playback, and the like in the sound system can not consider the phase relationship of each of the partial sounds in the complex sound.
The human ear is a frequency analyzer, which can separate the homophonic sounds in the polyphony. The sensitivity of the human ear to the frequency is very high. At this point, the human ear has higher resolution than the eye, and the human eye cannot see various kinds of white light. Colored light component.
Masking effect
Other sounds in the environment can cause the listener to reduce the hearing of a particular sound, which is called masking. When the intensity of one sound is much larger than the other, when the two sounds are both large and the two sounds exist at the same time, one can only hear the sound of the sound, but not the other. The amount of masking is related to the sound pressure of the masking sound, and the sound pressure level of the masking sound increases, and the masking amount increases. In addition, the masking range of the low frequency sound is larger than the masking range of the high frequency sound.
This auditory characteristic of the human ear provides an important inspiration for designing noise-reducing circuits. In tape playback, there is such a listening experience. When the music program is continuously changing and the sound is loud, we will not hear the noise floor of the tape. When the music program ends, we can feel 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 is proposed, that is, the signal strength is required to be sufficiently larger than the noise intensity, so that the listening does not feel the presence of noise. Some noise reduction systems are designed using the principle of masking effects.
Binaural effect
The basic principle of the binaural effect is this: if the sound comes from the front of the listener, the time difference (phase difference) and the timbre of the sound wave reaching the left and right ears are equal due to the equal distance of the sound source to the left and right ears. Zero, at this point the sound is coming from the front of the listener, not to one side. When the sound is different, you can feel the distance between the sound source and the listener.
Haas effect
Haas's test proves that when two sound sources are simultaneously sounded, the feeling of binaural listening is different according to the delay amount of one sound source and the other sound source, which can be divided into the following three cases. :
1. When the delay of one sound source and the other sound source is within 5 - 35ms, it is as if the two sound sources are combined into one. The listener can only feel the existence of a previous sound source. And the direction does not feel the existence of another sound source.
2. If one sound source delays another sound source for 30-50ms, the existence of two sound sources can be felt, but the direction is still determined by the predecessor.
3. If the delay of one sound source is greater than 50ms of the other sound source, then the two sound sources can be felt at the same time, the direction is determined by each sound source, and the lag sound is a clear echo.
Lloyd's effect
The Lloyd's effect is a psychoacoustic effect of the stereo range. The Lloyd's effect reveals that if the delayed signal is re-inverted and superimposed on the direct signal, it will produce a distinct sense of space. The sound seems to come from all directions, and the listener seems to be in the band.
Depoe effect
The Depoe effect is another basis for stereo system orientation. The experiment of the Depoe effect is: placing two speakers on the left and right channels. The listener listens to the two speakers on the symmetry line and feeds the two speakers with different signals. The following conclusions can be obtained:
1. If the two speakers are fed the same signal, that is, the intensity difference L=0, the time difference t=0, only one sound is felt at this time, and the symmetry lines from the two speakers.
2. If the intensity difference L of the two speakers is not 0, then the speaker feels that the sound is biased toward a louder speaker. If the intensity difference L is greater than or equal to 15 dB, then the sound is completely from the louder speaker.
3. If the intensity difference is L=0, but the time difference t between the two speakers is not 0, then the sound is moved in the direction of the speaker that arrives first. If the time difference t is greater than or equal to 3 ms, the sound is completely from the direction of the speaker that arrived first.
Keyhole effect
The mono recording system uses a microphone to record, the signal is recorded on a track, and one amplifier and one speaker are used for playback, so the sound source is a point source, just like the listener passes the key on the door. The hole listens to the symphony in the room, which is the so-called keyhole effect.
Bathroom effect
When you are in the bathroom, you have a personal feeling, the sound in the bathroom, the reverberation time is too long and excessive, this phenomenon is called the bathroom effect in the sound quality description of electro-acoustic technology. When the low and medium frequency segments are exaggerated, there is resonance, the frequency response is not flat, and the 300Hz boost is excessive, the bathroom effect will occur.
Doppler effect
The Doppler effect reveals the listening characteristics of moving sounds: when there is relative motion between the sound source and the listener, it will feel that the sound determined by a certain frequency changes its pitch when the sound source approaches the listener. The time is a tone with a slightly higher frequency, and when the sound source is gone, it is a tone with a slightly lower frequency. The amount of change in this frequency is called the Doppler shift. The moving sound source is greater at the same distance from the listener than when it is not moving, and the removed sound source produces less intensity, usually the sound source is concentrated toward the moving direction.
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