Room Acoustic Filter Design for Mode Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for improving sound quality in rooms suffer from limitations, such as only checking single frequencies at a time, not focusing on specific frequencies, and often leading to a deterioration of sound quality at locations other than the listening position.
Innovation Solution
A method using a single microphone measurement to focus on specific problematic frequencies caused by room modes, generating a set of filters to reduce the effect of room resonances on sound quality, which can be applied in both loudspeaker and microphone signal chains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple microphones are used to measure room acoustics, then measurement accuracy and coverage are improved, but device complexity and cost increase
Solution Approach 1:
The patent segments the frequency spectrum into multiple bands and uses a single microphone to measure each band separately at different positions. This allows comprehensive room acoustic characterization without requiring multiple microphones simultaneously, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent introduces the time dimension by measuring impulse responses at different positions and using deconvolution to separate direct sound from reflections. This temporal analysis enables accurate room acoustic measurement with a single microphone, avoiding the need for multiple spatial microphones.
2Manufacturing precision
If corrections are applied based on loudspeaker position relative to room walls, then frequency response is improved at listening position, but sound quality deteriorates at other locations
Solution Approach 1:
The patent applies local quality by measuring and correcting room acoustic modes at multiple specific positions around the loudspeaker, not just at the listening position. Each position provides localized information about room interactions, enabling corrections that improve sound quality across multiple locations simultaneously.
Solution Approach 2:
The patent uses feedback by measuring the actual sound pressure level at multiple positions and using this information to adjust the equalization settings. The system iteratively refines the correction based on real measurements, ensuring that frequency response improvements are achieved consistently across different listening positions.
3Manufacturing precision
If room modes are attenuated using traditional methods, then sound quality at specific position is improved, but overall sound quality and adaptability are reduced
Solution Approach 1:
The patent achieves universality by developing a measurement and correction method that works for multiple loudspeaker positions and listening positions simultaneously. The system can characterize room acoustic modes from any position and generate corrections that improve sound quality across the entire room, making the solution universally applicable.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting equalization settings based on the measured room acoustic modes and the specific loudspeaker and listening positions. The system changes frequency response parameters adaptively to compensate for room mode effects, improving sound quality across different locations without fixed corrections.
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
The method effectively enhances subjective sound quality by reducing the audibility of room modes, improving sound quality for both loudspeakers and microphones, and can be implemented in a wide range of products, including those with internal microphones.
Implementation Method 1
measurement of sound pressure level (SPL) at the listening position in a room
Implementation Method 2
determining a set of filters to be inserted in the signal chain... that reduce a room resonance's effect
Data Source
AI summary
The invention relates to a method for improving the sound quality of a sound reproduction or recording in a room, the method comprising the steps of measuring an impulse response that comprises the linear response of the room; performing a time domain analysis to determine the resonances of the room and for a chosen group of room resonances determining a corresponding group of filters that, when inserted in a sound reproduction or recording chain in said room will counteract the unwanted effect of said chosen group of room resonances on the sound quality of sound reproduction or recording made in the room. The invention further relates to a device designed to implement the method according to the invention and to the use of a measure of amplitude decay as a function of frequency of a measured impulse response of a sound reproduction or recording system in a room to determine one or more resonance frequencies, the total or partial compensation of which will improve the sound quality of sound reproductions or recordings made in the room.