Array Speaker Crossover Layout for Rear Channel Sound Imaging
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Solution Overview
Problem
The existing array speaker systems face challenges in generating high-quality surround sound fields due to the broad directivity of low-frequency sound beams, which leads to rear channel signals being heard directly from the front, causing echolocation issues and time alignment problems, as the beams are attenuated and overlap easily.
Innovation Solution
The system employs a two-way configuration where high-frequency signals are shaped into beams using an array speaker, while low-frequency signals are not shaped into beams and are output separately by dedicated low-frequency speakers, with distinct crossover frequencies for front and rear channels to optimize beam design and reduce echolocation and time alignment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the array speaker system uses a single crossover frequency for both front and rear channels, then the system structure is simple, but the rear channel sound image quality deteriorates due to broad directivity in low frequency band causing echolocation difficulties and time alignment problems
Solution Approach 1:
The patent applies local quality by setting different crossover frequencies for different channels: a first crossover frequency for front channels and a second crossover frequency for rear channels. This allows each channel to have optimized beam characteristics suitable for its specific spatial requirements, improving rear channel sound image quality without requiring complete system redesign.
2Power
If the array speaker system shapes low frequency bands into beams for rear channels, then the sound volume is enhanced, but the directivity becomes too broad causing beam overlap with front channels and time alignment issues
Solution Approach 1:
The patent changes the frequency parameter by introducing a second crossover frequency specifically for rear channels that is higher than the first crossover frequency for front channels. This parameter change limits the low frequency band beam shaping for rear channels, preventing excessive directivity broadening while maintaining adequate sound volume and achieving stable sound field composition.
3Adaptability or versatility
If the array speaker system uses a wide frequency band for beam shaping in rear channels, then the music reproduction coverage is improved, but the echolocation stability deteriorates due to time alignment problems
Solution Approach 1:
The patent applies local quality by differentiating the frequency band handling between front and rear channels through distinct crossover frequencies. Rear channels use a higher second crossover frequency that limits low frequency beam shaping, ensuring stable echolocation, while still maintaining adequate music reproduction coverage through the optimized frequency distribution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the quality of the rear channel sound image and reduces echolocation and time alignment problems by shaping front channels into a broad band and rear channels into a narrow band, enhancing the overall surround sound field experience.
Implementation Method 1
outputting multichannel sound beams to generate virtual sound sources by a reflection from the wall
Data Source
AI summary
Signals on respective RL, FL, C, FR, RR channels are divided into high frequency signals and low frequency signals by HPFs and LPFs respectively. The low frequency signals on the RL, FL, and C channels are superposed and output from a left-side woofer 21-1, while the low frequency signals on the RR, FR, and C channels are superposed and output from a right-side woofer 21-2. A predetermined directivity is given to the high frequency signals on respective channels by directivity controlling portions 17-1 to 17-5 respectively, and resultant signals are output from respective speaker units 20-1 to 20-n of an array speaker to generate virtual sound sources by the reflection from wall surfaces. A crossover frequency f2 of the rear channels (RL, RR) is set higher than a crossover frequency f1 of the front channels (FL, FR), and the signals on the rear channels are shaped into a narrow beam to generate a high-quality surround sound field.