14 laws of sound technology

There are 14 laws in sound technology. Do you know what it is?

1. Subjective perception of the frequency domain

The most important subjective feeling in the frequency domain is the pitch. The tone like the loudness is also the subjective psychological quantity of the auditory. It is the attribute of the auditory judgment of the sound level.

The difference between the pitch in psychology and the scale in music is that the former is the tone of pure tone, while the latter is the tone of a composite sound such as music. The tone of the composite sound is not simply a frequency analysis, but also a function of the auditory nervous system, which is influenced by the listening experience and learning of the listener.

2. The subjective feeling of the time domain

If the length of the sound exceeds approximately 300 ms, then the increase or decrease in the length of the sound does not contribute to the threshold change of the hearing. The feeling of tone is also related to the length of time of the sound. When the sound lasts for a short time, you can't hear the tone, just hear the "squeaky" sound. The duration of the sound is lengthened to have a feeling of tone. Only when the sound lasts for more than tens of milliseconds, the perceived tone can be stabilized.

Another subjective sensory characteristic of the time domain is the echo.

3. The subjective feeling of the space domain

The human ear has a distinct advantage over the use of binaural listening, with high sensitivity, low listening valve, a sense of direction to the sound source, and a relatively strong anti-interference ability. In stereo conditions, the sense of space obtained by listening to speakers and listening to stereo headphones is different. The sound heard by the former seems to be in the surrounding environment, while the sound heard by the latter is located inside the head, in order to distinguish between the two. The sense of space, the former is called orientation, the latter is called positioning.

4. Hearer's law of hearing

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.

5. Hearing 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.

6. 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, but when the music program ends (blank tape), we can feel it. The "咝..." noise to the tape 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, 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.

7. 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.

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