【 Weak current College 】 stereo and dual ear effect---Power By 【 China power house network 】

The concept of stereo
Stereo, as its name suggests, refers to a three-dimensional sound.
First of all, it is a geometric concept, refers to occupy a position in three dimensions. Then there is also a stereo sound room? the answer is Yes. Because sound sources have identified the location of the space, the sound is determined by the direction of the source, people's hearing distinguish sound source position. In particular, there are multiple sound sources at the same time, it can sound with auditory perception individual sound sources in the space distribution of the location. In this sense, the nature of all sound is in stereo. As the Thunder, train, guns and sound, etc.

When we directly hear these sounds in three-dimensional space, in addition to being able to feel the intensity of the voice, pitch and timbre, but also can feel their positions and levels. Such people directly heard with azimuth hierarchy, the spatial distribution of characteristics of sound, known as the stereo in nature.
Secondly, the nature of the sound is in stereo, but if we take these stereo amplified by the record, and so on processing and playback, all sound from a speaker, this heavy burst (as compared with the original sound source) is not a stereo. At this time due to various sounds are issued from the same speaker, the original sense of space (in particular sound sense of space distribution groups) is also gone. This weight was known as a single sound.
If the replay from the records to the entire system to a certain degree of recovery in the original sense of space (never completely), so that such a degree of azimuth levels and so the spatial distribution of weight was called stereo audio technology.
Binaural effect
In order to recover aloud in heavy sense of space, it is first necessary to understand the human auditory system why distinguish sound source position. The study found that this was mainly because people have two ears of sake (only one ear is hearing people do not feel the sound).
Because human beings are two ears to listen to the sound growth of the ears in the sides of the head, it not only has the distance in space, and head of barrier, therefore two ear receives a voice will have all these differences. The adoption of sound arrives at the ears of the time difference, the differential, the phase difference and sound timbre difference for sound and image orientation of the effect called binaural effect.
1. the sound reaches the ears of the time difference
Due to the left and right ears have a certain distance, therefore, in addition to the front and rear from is sound, the other direction voices reached the ears of time have been causing a time difference. If the sound source to the right, the sound must first to reach the left ear after the right ear. Sound sources more in favour of one side, the time difference. Experiment proves that, when the sound source in two ears line, the time difference is about 0.62ms.
2. sound arrives at the ears of acoustic differentials
The distance between the ears are very close, but because the skull on sound barrier function, the sound reaches the ears of the sound level may be different. If the sound source to the left, then left ear sensory sound level, and the right ear sound level. When the sound source in two ears line, sound differentials can reach around 25db.
3, the sound reaches the ears phase difference
The sound is transmitted in the form of waves, sound waves in space to a different location on the phase is different (unless you just are a wavelength). As the two ear distance in space, the sound waves reach the ears of phase may be different. Ear eardrum is within and with the Sonic vibration, the vibration of the phase difference has become we distinguish the sound source position. Of course, the lower the frequency, phase difference results in a stronger position feel.
4. the sound reaches the ears of tone color difference
Sonic if a direction from the right there, you want to bypass some parts of the head in order to reach the left ear. Known wave diffraction capabilities with wavelength and obstructions in proportion to the scale. Head diameter of about 20cm, quite and 1700Hz Sonic's wavelength, so the frequency to 1000Hz more Sonic bypass brain capacity, the greater the attenuation. That is, with one voice in a power capacity of bypassing the head, the higher the frequency, the greater the amount of attenuation. So the left ear with the hearing in one ear and hear the tone, timbre. As long as the sound from the front (or back), the ears hear the tone is different, this is people distinguish sound source position of a basis.
5, the differences caused by the auricle
Auricle is forward, clearly can reach people distinguish between front and rear. On the other hand, the ear's shape is very delicate, different aspects to voice will in which complex effect, therefore, ear to sound like the location also has a secondary role.
Binaural sound according to the time difference, although the differential, the phase difference and tone difference to navigate to the sound source, the acoustic positioning of the differential is based mainly on the treble, the phase difference is the main basis for bass positioning, positioning of the phase difference is based mainly on bass, quenching audible (blink too) with the time difference is positioned more accurate, non-pure cause poor positioning easier timbre. In short, Binaural effect is comprehensive, people of auditory system is based on the integrated effect to identify the location of the sound source.