Acoustic System Private Sound Zone via Phase Inversion
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Solution Overview
Problem
Conventional audio systems in aircraft and automobiles require users to wear headphones or earphones, which can be uncomfortable and lead to sound leakage, making it difficult to reproduce sound privately without disturbing others.
Innovation Solution
An acoustic system utilizing a directivity control device and speaker unit pairs that generate processed acoustic signals with opposite phases, ensuring sound is audible only in a limited range near the speaker units and inaudible elsewhere, achieved through specific signal processing and speaker arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a speaker is used for sound reproduction, then the user does not need to wear earphones or headphones, but the reproduced sound reaches the periphery of the user and causes trouble to other users
Solution Approach 1:
The sound reproduction system is segmented into multiple speaker units arranged in specific configurations (e.g., multiple speakers around the user's head position). Each speaker unit operates independently with controlled directivity, allowing the sound field to be divided into private zones for the user while preventing sound leakage to adjacent areas.
Solution Approach 2:
The patent applies local quality by creating different acoustic characteristics in different spatial zones. The sound reproduction is optimized to provide high-quality audio in the immediate vicinity of the user's ears while deliberately reducing sound intensity and quality in peripheral areas to prevent disturbance to other users.
2Ease of operation
If wavefront synthesis technology is used to synthesize a virtual sound field, then earphones or headphones are not needed, but a large-scale speaker array is required which is not realistic
Solution Approach 1:
Instead of implementing a complete wavefront synthesis system requiring a large-scale speaker array, the patent applies partial action by using a limited number of speaker units positioned strategically around the user. This partial implementation achieves the essential goal of private sound reproduction without the excessive complexity of a full wavefront synthesis system.
Solution Approach 2:
The patent inverts the conventional wavefront synthesis approach by not attempting to create a complete virtual sound field. Instead, it focuses on creating localized sound zones using opposite phase signals from multiple speaker units, achieving private sound reproduction through a simplified configuration rather than through comprehensive wavefront manipulation.
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 can be heard only in a very narrow range, specifically near the speaker system, reducing disturbance to others and eliminating the need for headphones or earphones.
Implementation Method 1
generates a second processed acoustic signal from an acoustic signal (hereinafter, referred to as a second acoustic signal) having an opposite phase to the first acoustic signal
Implementation Method 2
causing a sound emitted from the positive speaker unit of the speaker unit pair and a sound emitted from the negative speaker unit of the speaker unit pair to be audible in an area to be made audible near the speaker unit pair and to be inaudible in an area to be made inaudible
Data Source
AI summary
Provided is an acoustic system for a user who uses a seat of an aircraft, 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 directivity control device including at least one directivity control unit that generates a first processed acoustic signal from a first acoustic signal and generates a second processed acoustic signal from a second acoustic signal having an opposite phase to the first acoustic signal by executing predetermined signal processing; and a speaker system including at least one speaker unit pair including a positive speaker unit that emits a sound based on the first processed acoustic signal and a negative speaker unit that emits a sound based on the second processed acoustic signal, in which the signal processing executed by the directivity control unit is processing of causing a sound emitted from the positive speaker unit of the speaker unit pair and a sound emitted from the negative speaker unit of the speaker unit pair to be audible in an area to be made audible near the speaker unit pair and to be inaudible in an area to be made inaudible.