Loudspeaker Back Enclosure Active Noise Control
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Solution Overview
Problem
Loudspeaker enclosures suffer from reduced performance below the resonance frequency due to back radiation interference, leading to inefficient sound wave production and acoustic pressure buildup, which existing technologies have not effectively addressed through active noise control methods.
Innovation Solution
An acoustics management system that includes a primary loudspeaker with a secondary loudspeaker placed within the enclosure to cancel backside waveforms using active noise cancellation (ANC) techniques, with sensors and ANC systems to calculate and generate anti-noise waveforms to negate unwanted sound or pressure emanating from the backside of the primary loudspeaker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a loudspeaker is placed in a closed box enclosure, then back-to-front cancelation is prevented, but the output curve shifts upward in frequency and performance degrades below resonance frequency
Solution Approach 1:
The patent applies preliminary anti-action by using an active noise control system to generate anti-phase sound waves that preemptively counteract the back radiation from the loudspeaker. The ANC system detects back radiation and produces opposing sound waves before they can cause harmful interference, thereby maintaining low-frequency performance while preventing cancelation effects.
2Productivity
If a bass reflex enclosure is used to extend bass response, then low frequency output is improved, but transient response degrades and the vent becomes noisy at high sound levels
Solution Approach 1:
The patent replaces the mechanical bass reflex vent system with an active noise control system. Instead of using a physical port that requires air movement and creates noise and transient response issues, the ANC system uses electronic signal processing and secondary loudspeakers to generate anti-phase waves, eliminating the need for a mechanical vent while achieving similar bass extension.
3Volume of stationary object
If the enclosure volume is reduced to fit the loudspeaker, then device size is decreased, but acoustic pressure buildup increases and performance drops below resonance frequency
Solution Approach 1:
The patent uses preliminary anti-action by implementing an active noise control system that generates anti-phase sound waves to counteract pressure buildup in the reduced-volume enclosure. The ANC system detects pressure variations and produces opposing acoustic pressure, allowing the enclosure to maintain small size without suffering from harmful pressure accumulation that would degrade low-frequency performance.
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 enhances loudspeaker performance by effectively canceling backside radiation, improving sound output and reducing negative pressure buildup, thereby extending the frequency response and maintaining efficiency across a broader range of frequencies.
Implementation Method 1
An acoustics management system that includes a primary loudspeaker with a secondary loudspeaker placed within the enclosure to cancel backside waveforms using active noise cancellation (ANC) techniques, with sensors and ANC systems to calculate and generate anti-noise waveforms to negate unwanted sound or pressure emanating from the backside of the primary loudspeaker.
Data Source
AI summary
An active acoustics management system for the loudspeaker back-enclosure, including a first loudspeaker having a front side and a back side connected by side walls, the front facing in a first direction, is presented. An enclosure surrounds a portion of the first loudspeaker, such that the enclosure is open about the front side of the first loudspeaker and is closed about the side walls and the back side of the loudspeaker. A second loudspeaker is disposed within the enclosure behind the first loudspeaker, the second loudspeaker being oriented to output waveforms in the first direction, wherein the second loudspeaker is adapted to output waveforms in the first direction thereby to cancel at least some waveforms emanating from the back side of the first loudspeaker, using active control strategies.