Adaptive Playback Equalization for Audio Devices
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Solution Overview
Problem
Personal audio devices face challenges in maintaining optimal audio performance due to changing acoustic environments and the limitations of static equalizers, which fail to adapt effectively to ambient noise and electro-acoustic path variations.
Innovation Solution
A personal audio device incorporating a transducer, error microphone, and processing circuits that generate an anti-noise signal and adaptively equalize the audio signal using noise cancellation and playback equalization systems, minimizing differences between the source and error microphone signals to improve sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a static equalizer is used, then the device structure remains simple, but the audio performance cannot adapt to environmental changes
Solution Approach 1:
The patent implements an adaptive equalizer that dynamically adjusts its frequency response based on real-time environmental conditions and acoustic feedback. The equalization filter continuously adapts its parameters to compensate for changes in the electro-acoustic path, transforming a static system into a dynamic one that responds to environmental variations.
Solution Approach 2:
The system uses an error microphone to capture the actual acoustic output and feeds this signal back to the adaptive equalizer. This feedback loop enables the equalizer to continuously monitor and adjust its response based on the actual sound reproduction, allowing adaptation to environmental changes while maintaining audio quality.
2Adaptability or versatility
If noise cancellation is added to adapt to environmental changes, then audio performance improves, but device complexity increases
Solution Approach 1:
The patent combines adaptive equalization and active noise cancellation into a single integrated signal processing system. Both functions share common components including the error microphone, adaptive filters, and processing circuitry, allowing the device to provide both equalization and noise cancellation without proportionally increasing complexity.
Solution Approach 2:
The adaptive filter system serves multiple functions simultaneously: it performs both equalization to correct frequency response and noise cancellation to reduce ambient sounds. This multi-functionality allows the system to address multiple audio quality issues with a unified approach, reducing overall system complexity compared to separate dedicated systems.
3Manufacturing precision
If adaptive equalization is implemented, then sound quality improves, but processing requirements and device complexity increase
Solution Approach 1:
The adaptive equalizer focuses on correcting only the most significant frequency response deviations rather than attempting perfect correction across all frequencies. This partial action approach provides sufficient audio quality improvement while limiting the computational complexity and processing requirements of the system.
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 solution enhances audio intelligibility by effectively reducing ambient noise and adapting to environmental changes, providing improved sound quality compared to traditional static equalization methods.
Implementation Method 1
a transducer (22) coupled to the housing for reproducing an output audio signal
Implementation Method 2
an error microphone (24) coupled to the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer
Implementation Method 3
generates an anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
In accordance with systems and methods of the present disclosure, a method may include receiving an error microphone signal indicative of an acoustic output of a transducer and ambient audio sounds at the acoustic output of the transducer. The method may also include generating an anti-noise signal to reduce the presence of the ambient audio sounds at the acoustic output of the transducer based at least on the error microphone signal. The method may further include generating an equalized source audio signal from a source audio signal by adapting, based at least on the error microphone signal, a response of the adaptive playback equalization system to minimize a difference between the source audio signal and the error microphone signal. The method may additionally include combining the anti-noise signal with the equalized source audio signal to generate an audio signal provided to the transducer.