Vehicle Audio Phase Control for Quiet Seat Sound Zones
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Solution Overview
Problem
Existing methods for adjusting sound levels in a vehicle compartment, such as those involving speaker arrays or separate speakers near each passenger, fail to effectively reduce sound levels at specific positions without affecting other seats or requiring large systems, particularly when trying to keep a seat quiet for passengers like babies or children.
Innovation Solution
A volume control device connected to speakers in front of and behind a listening position, which calculates and controls the phase difference of sound signals at frequencies below a predetermined frequency to reduce sound levels at the listening position without affecting other seats, using a phase controller to manage the sound signals supplied to the speakers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the volume of the front and rear speakers is reduced, then the assistant driver's seat becomes quiet, but it becomes difficult to hear the sound at the rear seats
Solution Approach 1:
The patent applies local quality by creating different sound environments for different seating positions. The phase control unit independently controls the phase of sound signals for each speaker, enabling the assistant driver's seat to experience quiet conditions while rear seats maintain adequate sound levels. This localized sound control achieves position-specific audio characteristics without uniformly affecting all seating areas.
Solution Approach 2:
The patent changes the phase parameter of sound signals to achieve differential sound control. By adjusting the phase of front and rear speakers independently, the system creates constructive and destructive interference patterns that result in quiet zones at the assistant driver's seat while maintaining sound quality at rear seats. This parameter manipulation resolves the contradiction between local quietness and overall sound distribution.
2Manufacturing precision
If the volume of only the rear speakers is increased, then it becomes easy to hear the sound at the rear seats, but it becomes difficult to sufficiently keep the assistant driver's seat quiet because the sound from the rear speakers reaches the assistant driver's seat
Solution Approach 1:
The patent applies preliminary anti-action by introducing sound waves with opposite phase to counteract unwanted sound propagation. The phase control unit adjusts the phase of front speakers to create destructive interference with sound waves reaching the assistant driver's seat from rear speakers. This preemptive phase adjustment prevents sound from accumulating at the assistant driver's position while allowing rear seats to receive adequate sound.
Solution Approach 2:
The patent utilizes phase parameter changes to achieve directional sound control. By independently manipulating the phase parameter of each speaker, the system enables rear speakers to operate at high volume for rear seat passengers while the phase-adjusted front speakers cancel out sound propagation to the assistant driver's seat, resolving the contradiction between rear seat audio quality and assistant driver's seat quietness.
3Manufacturing precision
If separate speakers are arranged at the positions near the ears of each passenger, then the sound control for each seat is improved, but the arrangement of the speakers becomes special and the low frequency component of the reproduced sound can still reach other seats
Solution Approach 1:
The patent applies universality by making existing front and rear speakers perform multiple functions. Instead of adding separate speakers for each seat, the system enables the front and rear speakers to simultaneously serve their original positions and create zone-specific sound control through phase manipulation. This multi-functional approach achieves precise sound control for different seating areas without requiring special speaker arrangements or additional hardware.
Solution Approach 2:
The patent uses phase parameter changes to achieve frequency-specific sound control without modifying the physical speaker arrangement. By adjusting the phase parameter of sound signals, the system creates frequency-dependent interference patterns that prevent low frequency components from propagating to unwanted areas while maintaining high frequency directional control. This parameter-based solution avoids the complexity of reconfiguring speaker positions or adding specialized speakers.
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 solution allows for the reduction of sound levels at specific positions in a vehicle compartment without impacting other seats, ensuring that the listening position remains quiet while maintaining adequate sound levels elsewhere, thus addressing the challenge of keeping an assistant driver's seat quiet without requiring a large system.
Implementation Method 1
calculate a phase difference, at a frequency lower than a predetermined frequency, between a sound signal reproduced by the speaker in front of the listening position and a sound signal reproduced by the speaker behind the listening position
Data Source
AI summary
A volume control device controls reproduced sound levels at the listening position set to the seat in the vehicle compartment, and gives the phase difference to an externally inputted sound signal, and supplies the sound signals to two speakers. Here, the phase difference is calculated, at a frequency lower than a predetermined frequency, for sound signals reproduced by the speakers in front of and behind the listening position. Also, the phase difference is calculated to make a reproduced sound level at the listening position smaller than the reproduced sound level when the sound signal is reproduced by either one of the pair of speakers. Preferably, the listening position includes two evaluation points, and the reproduced sound level at the listening position is a sum of the reproduced sound levels at the two evaluation points. Thus, the reproduced sound may become small at an arbitrary listening position in the acoustic space.