The ability to generate 3D audio is highly desirable to create an auditory experience which provides a certain level of spaciousness and envelopment. Spaciousness may be achieved using a two-channel (stereo) or multi-channel system. However, in a two-channel system, spaciousness and depth dimension are constrained by the space between two conventional loudspeakers. The level of envelopment depends on the number and spacing of loudspeakers, which is only available in a multi-channel system. Due to the limitations of conventional loudspeakers, it remains difficult to achieve immersive sounds for 3D media. Although setting up surround loudspeakers in a multi-channel system may achieve 3D audio effects, it may be problematic in an environment with limited space.
This technology uses one directional loudspeaker for transmitting binaural cues extracted from the input signal and one conventional loudspeaker for transmitting ambience sound. This helps to create a highly-focused sound image comprising vivid auditory images close to users while still projecting background audio.
The sub-band approach is used, which allows the use of different types of loudspeakers in the same system, thus allowing the use of cheaper loudspeakers with lower bandwidths for frequency bands which are less important. This in turn lowers the cost of the audio system.
With sub-band approach, the input signal may be down-sampled, thus lowering and varying the speed requirement for processing each frequency band and in turn lowering the speed requirement for processing the entire signal. This mixed-rate processing technique thus removes the need for high-end processors and instead, a low cost digital signal processor can be used to implement the processing system.
More variations may be made to the processing system using the sub-band approach (for example, the number of frequency bands, the processing technique for each frequency band etc. may be varied), allowing manufacturers of the audio system to differentiate their products in terms of pricing and applications.
Surround audio and accurate audio projection are crucial in the consumer AV markets. This technology describes an augmented audio system that combines both directional and conventional loudspeakers to create a highly immersive audio experience.