Speaker Array Sound Beam Localization in Limited Reflection Rooms
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Solution Overview
Problem
Conventional speaker array systems struggle to provide a strong surround effect when the room layout limits the direction in which sound images can be perceived, often resulting in weakened sound localization behind a listener due to the absence of reflective surfaces.
Innovation Solution
A speaker array apparatus with a directivity control section and a frequency characteristic applying section that adjusts sound beam directivity and frequency characteristics based on the listening position and room shape, using head-related transfer characteristics to simulate sound image localization, even when directivity cannot be determined by conventional means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sound beams are output using reflection on wall faces, then sound images can be localized in the wall face direction, but sound images cannot be localized behind the listener when no wall face exists behind the listener
Solution Approach 1:
The patent creates virtual sound sources by copying and processing audio signals through frequency characteristic application. When direct sound beam reflection is not possible (no wall behind listener), the system synthesizes equivalent acoustic effects by applying frequency characteristics that simulate how sound would behave if reflected, thereby creating virtual sound images behind the listener without requiring physical reflective surfaces
Solution Approach 2:
The patent changes frequency parameters of audio signals to achieve sound image localization. By applying frequency characteristics (equalization) to audio signals destined for rear channels, the system modifies the spectral content to create directional perception, enabling sound images to be localized behind the listener through parameter modification rather than relying on physical room geometry
2Reliability
If channels SL and SR are mixed with channels FL and FR to localize in front direction, then sound beams can arrive at listening position, but the surround effect is weakened
Solution Approach 1:
The patent applies different frequency characteristics to different audio channels based on their intended localization direction. Rather than uniformly mixing all channels, the system selectively modifies frequency parameters for specific channels (particularly rear channels SL and SR) to achieve appropriate localization quality for each spatial position, maintaining surround effect while ensuring reliable sound beam arrival
Solution Approach 2:
The patent dynamically adjusts frequency characteristics of audio signals based on listening position and room geometry. The system adaptively changes spectral parameters in real-time depending on whether the listener is positioned where wall reflections are available or not, thereby dynamically optimizing both sound beam reliability and surround effect for each listening scenario
Data Source
AI summary
A speaker array apparatus for outputting sound beams of a plurality of channels based on audio signals of the plurality of channels, includes a directivity control section that controls a directivity of at least one of the sound beams of the channels so as to generate one or more pairs of the sound beams of the channels having roughly the same directivity, and a frequency characteristic applying section that applies a frequency characteristic to the audio signal corresponding to one of the sound beams of the channels in the one or more pairs to change a sound image localization position of the one of the sound beams of the channels in the one or more pairs.