Networked Speaker Noise Cancellation Using Directional Transducers
Solution Overview
Problem
Existing noise canceling techniques are ineffective at high frequencies and in unknown acoustic environments with non-fixed loudspeaker locations, failing to adequately minimize sound leakage from speaker systems.
Innovation Solution
A wireless audio speaker system with transducers oriented at an oblique angle, utilizing microphones and processors to generate noise cancellation signals based on speaker location and acoustic characteristics, employing active noise canceling algorithms to limit sound dispersion by directing sound inward and canceling noise outward.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing noise canceling techniques are used, then low-frequency sound cancellation is achieved, but high-frequency sound leakage remains unaddressed
Solution Approach 1:
The patent changes the operating parameters of the noise cancellation system by extending the frequency range of active noise cancellation from traditional low frequencies to include high frequencies up to 20kHz. This is achieved through adaptive filtering algorithms that process wideband audio signals, enabling effective cancellation across the entire audible spectrum rather than being limited to low frequencies only.
Solution Approach 2:
The system employs dynamic adaptation to unknown acoustic environments by continuously adjusting filter coefficients based on real-time microphone feedback. The adaptive noise cancellation algorithm dynamically modifies its parameters to account for varying acoustic conditions, speaker positions, and environmental changes, making the system effective in previously unknown or changing acoustic spaces.
2Adaptability or versatility
If noise cancellation is implemented in unknown acoustic environments with non-fixed loudspeaker locations, then flexibility is improved, but cancellation accuracy deteriorates
Solution Approach 1:
The patent implements feedback mechanisms using microphones positioned to capture sound from the loudspeaker and environment. The captured audio signals are fed back to the adaptive filter, which continuously adjusts its coefficients to optimize noise cancellation. This closed-loop feedback system enables the system to automatically adapt to unknown acoustic environments and maintain high cancellation precision regardless of speaker location or environmental changes.
Solution Approach 2:
The system performs preliminary characterization of the acoustic environment by analyzing microphone feedback signals before full noise cancellation operation begins. This preliminary action includes estimating acoustic transfer functions and identifying environmental characteristics, which prepares the adaptive filter for more accurate cancellation in the subsequent operation phase.
3Object-affected harmful factors
If transducers are oriented upwardly at oblique angles for directional sound projection, then sound containment is improved, but coverage area is reduced
Solution Approach 1:
The patent applies different functional characteristics to different spatial zones by directing sound energy preferentially toward the listening area while using noise cancellation to suppress sound in other directions. The upwardly oriented transducers create a localized zone of enhanced sound projection toward the audience, while adaptive noise cancellation creates zones of suppressed sound leakage in other directions, achieving directional control without uniformly reducing coverage.
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 effective noise cancellation in various environments, allowing for high-volume music playback without disturbing neighbors, by using directional sound projection and adaptive noise cancellation signals to reduce both high-frequency and low-frequency sound leakage.
Implementation Method 1
at least a first transducer defines a sonic axis oriented upwardly at an oblique angle with respect to horizontal
Implementation Method 2
identify noise cancellation signals to cancel second sound that is produced using the other of the first transducer and the third transducer
Data Source
AI summary
A networked speaker system includes plural speaker assemblies around the perimeter of a space with sound axes oriented up and inward into the space. Each speaker assembly includes an audio transducer to output demanded sound and a noise cancelation transducer which is driven to cancel sound from other speaker assemblies in the space based on signals from a microphone on the speaker assembly and location and device information from the other speaker assemblies.