Seat Acoustic Speaker Layout for Localized Sound Playback
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Solution Overview
Problem
Conventional methods of sound reproduction in aircraft or automobiles using earphones or headphones are cumbersome and can cause discomfort, and large-scale speaker arrays for virtual sound field synthesis are impractical.
Innovation Solution
An acoustic system utilizing a speaker unit that emits sound with opposing phases in different directions to cancel each other outside a specific range, allowing sound to be heard only in the vicinity of the speaker unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a speaker is used for sound reproduction, then the reproduced sound reaches the periphery of the user, but this causes trouble to other users
Solution Approach 1:
The patent applies local quality by creating a sound field with highly directional characteristics, concentrating acoustic energy in a specific local region (the user's listening position) while suppressing sound propagation in other directions. This is achieved through phase-controlled speaker arrays that generate constructive interference at the target position and destructive interference in surrounding areas, thereby providing convenient sound reproduction without disturbing other users.
Solution Approach 2:
The patent converts the harmful effect of sound propagation to surrounding areas into a beneficial feature by using the same physical phenomenon (sound wave interference) to create directional sound fields. The sound waves that would normally propagate in all directions and cause disturbance are instead controlled to interfere destructively in unwanted directions, transforming potential harm into the benefit of localized sound containment.
2Object-affected harmful factors
If earphones or headphones are used to prevent sound disturbance, then other users are not disturbed, but wearing them is troublesome and causes discomfort
Solution Approach 1:
The patent extracts the sound containment function from the personal audio device (earphones/headphones) and transfers it to the environmental sound reproduction system. Instead of containing sound within a personal device that contacts the user's ears, the system uses acoustic field control to contain sound in the air space, eliminating the need for physical contact and associated discomfort while maintaining the benefit of preventing disturbance to others.
3Measurement precision
If a large-scale speaker array is used for virtual sound field synthesis, then sound can be localized, but the system becomes impractical
Solution Approach 1:
The patent applies partial action by using a limited number of speaker units (far fewer than a full wavefront synthesis array would require) to achieve the essential function of directional sound reproduction. Rather than implementing the complete and complex wavefront synthesis system, the patent uses a simplified configuration with selective phase control that provides sufficient sound localization and directional control for practical applications.
Solution Approach 2:
The patent changes the operational parameters of the speaker system, specifically the phase relationships between speakers, to achieve directional sound fields. By controlling the phase difference between adjacent speakers (e.g., 180 degrees for back surface sound), the system creates constructive and destructive interference patterns that localize sound without requiring a large-scale array, thus reducing device complexity while maintaining sound localization accuracy.
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
Enables sound reproduction that is audible only in a limited, narrow range, eliminating the need for headphones and reducing disturbance to others.
Implementation Method 1
the sound emitted from the speaker unit in the front surface direction and the sound emitted from the speaker unit in the back surface direction cancel each other in a region in the front surface direction far from the speaker unit
Data Source
AI summary
There is provided an acoustic system for a user who uses a seat of an airplane, an automobile, or the like, which reproduces a sound that cannot be heard by surrounding users without using earphones or headphones. An acoustic system including a speaker system including one speaker unit that emits a sound based on an acoustic signal of a predetermined sound source, in which a sound emitted from the speaker unit is hearable in a region to be audible near the speaker unit, and by a sound emitted from the speaker unit in a back surface direction coming around to a front surface direction, the sound emitted from the speaker unit in the front surface direction and the sound emitted from the speaker unit in the back surface direction cancel each other in a region in the front surface direction far from the speaker unit.