Seat-Mounted ANC Filter Selection for Reclining Position Changes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The noise cancellation system installed on seats of aircraft, automobiles, etc., faces instability in noise cancellation due to adaptive learning of cancellation filter coefficients for sounds other than the noise source, such as the user's voice, and changes in the acoustic characteristics of the path from the speaker to the error microphone caused by seat reclining mechanisms.
Innovation Solution
A cancellation filter coefficient selection apparatus that records and selects cancellation filter coefficients based on the seat position, using a reference microphone and speaker installed on the seat, and adjusts the coefficients using a reference signal and an estimated error signal to stabilize noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive learning of cancellation filter coefficients is performed, then noise cancellation effectiveness is improved, but stability deteriorates due to learning sounds other than noise sources such as user voice
Solution Approach 1:
The patent segments the acoustic environment into different spatial zones by installing multiple reference microphones at different locations. Each reference microphone captures noise from specific directions, allowing the system to selectively process noise signals while excluding sounds from certain zones (such as user voice). This spatial segmentation enables the adaptive learning to focus only on noise sources while ignoring other sounds, resolving the contradiction between effectiveness and stability.
2Adaptability or versatility
If seat reclining mechanism is used to adjust seat position, then user comfort and adaptability are improved, but noise cancellation stability deteriorates due to changes in acoustic characteristics
Solution Approach 1:
The patent implements a dynamic adaptation mechanism where the system automatically adjusts to changes in seat position and acoustic characteristics. When the seat position changes due to reclining, the system detects the new acoustic environment and recalibrates the reference signals accordingly. This dynamic adjustment maintains noise cancellation effectiveness despite positional changes, resolving the contradiction between adaptability and stability.
Solution Approach 2:
The system employs feedback mechanisms using error microphones to continuously monitor the acoustic environment and detect changes caused by seat position adjustments. The detected changes are fed back to the control unit, which then adjusts the cancellation filter coefficients and reference signals to compensate for the acoustic characteristic changes. This closed-loop feedback maintains noise cancellation stability while allowing seat position flexibility.
3Ease of operation
If reference microphone and speaker are installed on the seat, then portability and ease of installation are improved, but measurement precision deteriorates due to position changes in predetermined space
Solution Approach 1:
The patent transforms the static reference signal acquisition approach into a dynamic one. Instead of relying on fixed positional relationships between microphones and noise sources, the system continuously adapts the reference signals based on detected acoustic characteristics. This dynamic approach maintains measurement precision despite the movable installation on seats, resolving the contradiction between ease of installation and measurement accuracy.
Data Source
AI summary
Provided is a technique for selecting a cancellation filter coefficient that can stably cancel noise for a user using a seat of an aircraft, an automobile, or the like. A cancellation filter coefficient selection apparatus includes: a recording unit configured to record cancellation filter coefficients; a seat position acquisition unit configured to acquire a position of a seat used by a user; and a cancellation filter coefficient selection unit configured to, from among the cancellation filter coefficients recorded in the recording unit, select a cancellation filter coefficient corresponding to the position of the seat as a cancellation filter coefficient to be used in filtering for generating a cancellation signal for cancelling noise at a position where quiet is desired, based on a reference signal output by a reference microphone configured to collect noise in a predetermined space. The reference microphone and a speaker for emitting sound based on the cancellation signal are installed on the seat, and positions of the reference microphone and the speaker in the predetermined space change accompanying movement of the seat.