Understanding 5.1 and 7.1 Surround Sound Configurations

Surround Sound, namely 环绕声，is an audio playback technology that creates an immersive auditory experience by arranging multiple speakers around the listener and distributing audio signals reasonably. It breaks the limitations of the linear sound field of traditional stereo, enabling the audience to perceive sounds from front, back, left, right and even the entire surrounding space, thus enhancing the sense of presence and spatial depth. The following is a detailed introduction to it:

Music Live and Studio: Some high-end concert halls and recording studios will adopt surround sound systems. This enables the audience to feel the surrounding sound of musical instruments and chorus, and also helps music producers make more delicate sound mixing adjustments to restore the on-site effect of the performance.

Core PrinciplesThe core is to use the human ear’s auditory characteristics such as the Haas effect and masking effect, and combine audio processing technologies like delay and phase shifting. It mixes the original sound with the sound that has been delayed for a certain period of time (usually tens to over 100 milliseconds). This not only avoids obvious echoes but also enhances the thickness and sense of space of the sound. Moreover, by assigning different audio signals to speakers in different positions, the audience can distinguish the direction and distance of the sound source, as if they are in the scene where the sound occurs.

Common Channel ConfigurationsDolby ProfessionalDifferent channel configurations are designed for different application scenarios, among which 5.1 and 7.1 are the most widely used:

5.1 Channel: It is the mainstream configuration in home theaters and digital broadcasts, consisting of 6 audio channels. Specifically, there are left and right front speakers (responsible for music and main sound effects in the front sound field), a center speaker (focused on character dialogue and foreground key sounds), left and right surround speakers (creating surrounding ambient sounds such as wind and footsteps), and a 0.1-channel subwoofer (dedicated to low-frequency effects like explosions and thunder to enhance the shocking effect).

7.1 Channel: On the basis of 5.1 channels, two more rear surround speakers are added, dividing the surround sound field into four independent areas. This configuration solves the problem of sound field deviation when the audience is not sitting in the best viewing position. It can achieve more precise sound positioning, and is often used in high-end home theaters and professional cinemas to make the sound transition between front and back more natural.

Main Technical StandardsDolby ProfessionalMany mainstream technical standards have been formed in the industry, which promote the standardized application of surround sound:

Dolby Series: Dolby Surround is an early analog matrix – type surround sound standard. Dolby Digital (AC – 3) is a digital standard widely used in 5.1 channels, and Dolby Surround 7.1 further expands the surround sound field control, which is commonly used in movie post – production.

THX: It is not a separate encoding format but a quality certification standard. It optimizes the audio playback effect by adjusting parameters such as frequency response and dynamic range to ensure that the audio can be presented as the creator intended in different playback environments.

DTS: It is often used in high-definition audio and video fields. It has the advantage of high audio fidelity and can transmit more detailed sound information. It is a common alternative to Dolby Digital in home theaters and Blu-ray discs.

Typical Application Scenarios

Cinema: It is the earliest and most typical application scenario. When watching action movies or science – fiction blockbusters, the audience can feel the sound of bullets whizzing past their ears and the rumble of aircraft flying overhead, which is highly integrated with the picture and enhances the viewing experience.

Home Theater: With the popularization of large-screen TVs and projectors, many families will set up 5.1-channel home theater systems. This allows them to enjoy the immersive audio-visual effect comparable to that of cinemas when watching movies or playing games at home.

Gaming and VR: In 3A games, surround sound can help players judge the enemy’s position through footsteps and gunfire. In VR devices, it can be combined with the visual virtual environment to create a more realistic virtual world, making users feel as if they are in the game scene.