Speaker Excursion Prediction for Low-Delay Over-Excursion Protection
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Solution Overview
Problem
Audio speakers are prone to damage and sound distortion due to excessive movement (over excursion) caused by amplification or signal processing, leading to degradation in sound quality and unwanted sounds.
Innovation Solution
A computing device and smart amplifier system that applies low-frequency and transient excursion protection to audio signals by predicting speaker movement and adjusting the signal to limit excursion below a maximum threshold, using sub-resonance and instantaneous excursion predictions based on speaker models and sensor feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If amplification or signal processing is applied to drive the speaker, then audio output quality is improved, but speaker excursion may exceed maximum limits causing damage or distortion
Solution Approach 1:
The system performs preliminary excursion prediction using speaker models before the actual speaker movement occurs. By analyzing the audio signal and predicting future excursion values, the system can preemptively adjust the audio signal to prevent over-excursion damage before it happens.
Solution Approach 2:
The system uses feedback from speaker parameters (such as impedance measurements) to continuously update the speaker model and refine excursion predictions. This closed-loop feedback mechanism allows the system to adapt to changing speaker conditions and maintain accurate protection thresholds.
2Reliability
If excursion protection is applied to prevent speaker damage, then speaker reliability is improved, but audio signal quality may be degraded due to signal adjustment
Solution Approach 1:
The system applies partial signal adjustment only when and where needed to prevent over-excursion. Rather than continuously attenuating the audio signal, the system selectively modifies only the portions of the signal that would cause harmful excursion, leaving the rest of the audio content unchanged to preserve fidelity.
Solution Approach 2:
The system dynamically changes audio signal parameters (such as gain or frequency content) based on predicted excursion levels. By adjusting parameters selectively rather than applying fixed attenuation, the system maintains audio quality while providing effective protection.
3Measurement precision
If complex excursion prediction algorithms are used to accurately predict speaker movement, then prediction precision is improved, but computational complexity increases
Solution Approach 1:
The system segments the excursion prediction into multiple stages: a first excursion prediction using a simplified model for quick assessment, and a second more accurate prediction for critical cases. This segmentation allows the system to achieve high accuracy when needed while maintaining low computational complexity for routine operation.
Solution Approach 2:
The system dynamically adjusts the complexity of prediction algorithms based on operating conditions. During normal operation, simpler models are used for efficiency; during critical excursions or transient conditions, more complex models are activated to provide accurate predictions when they matter most.
4Speed
If real-time excursion protection is applied to prevent speaker damage, then response speed is improved, but processing delay increases
Solution Approach 1:
The system performs excursion prediction in advance of the actual speaker movement using the relationship between audio signal and speaker response. By predicting excursion before it occurs, the system can adjust the audio signal proactively without introducing significant delay to the audio playback.
Solution Approach 2:
The system uses efficient computational methods to rapidly process excursion predictions and signal adjustments. By optimizing the calculation speed and using direct computation where possible, the system rushes through the protection processing quickly to minimize any delay in audio playback.
Data Source
AI summary
Systems and devices configured by an algorithm to prevent or limit a speaker over-excursion are disclosed. The disclosed algorithm is computationally efficient because it exploits a relationship between an audio signal and a speaker's excursion that exists at low-frequencies, below a self-resonance of a speaker. The disclosed algorithm combines the low-frequency excursion protection with a high-frequency, transient excursion protection. The combined approach allows the transient excursion protection to use a shorter delay than otherwise possible. The shorter delay allows for a compressor to apply attenuation to a transient audio signal before a momentum of the speaker, caused by the transient audio signal, grows too large to be controlled.