Broadcast Audio Equalization for Time-Varying Noise Profiles
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Solution Overview
Problem
Existing techniques for equalizing audiofrequency signals in noisy environments, such as vehicles, are inadequate as they fail to account for variable noise characteristics over time, leading to inconsistent perceived tonal balance.
Innovation Solution
A method that estimates the frequency profile of background noise using signals captured by microphones and the broadcast audio signal, determines a desired frequency profile, calculates a frequency acoustic mask, and applies a frequency weighting mask to equalize the audio signal, thereby adapting to changing noise conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SDVC technique is used to increase the volume of the entire audiofrequency signal, then the signal level increases above the masking threshold, but the perceived spectral balance is distorted because the increase is not linear around the masking threshold
Solution Approach 1:
The patent applies local quality by implementing frequency-specific equalization through a parametric equalizer that independently adjusts gain for different frequency bands. Instead of uniformly increasing the entire signal level as SDVC does, the system selectively applies gain compensation only to frequency bands that are masked by noise, preserving the natural spectral balance while effectively overcoming masking effects.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the equalizer parameters (center frequency, bandwidth, and gain) based on real-time noise spectrum analysis. The system continuously monitors the noise floor across different frequency bands and modifies the equalization parameters to compensate for masking effects, thereby maintaining accurate spectral balance under varying noise conditions.
2Adaptability or versatility
If SDEC technique is used with a low shelf filter, then low frequencies are increased above the masking threshold, but the solution assumes that the background noise profile depends only on vehicle speed, which is insufficient when noise sources vary
Solution Approach 1:
The patent implements dynamics by transitioning from a static equalization approach (SDEC with fixed low-shelf filter parameters) to a dynamic system that continuously adapts to changing noise conditions. The parametric equalizer parameters are continuously adjusted based on real-time noise spectrum analysis, allowing the system to respond to varying noise sources such as wind noise, road noise, and HVAC systems, thereby maintaining reliable spectral balance preservation across diverse operating conditions.
Solution Approach 2:
The patent applies universality by designing an equalization system that handles multiple types of noise sources and spectral shapes through a unified parametric equalizer framework. Unlike SDEC which only addresses low-frequency masking with a fixed low-shelf filter, the patent's parametric equalizer can adapt to mask any frequency band by adjusting its parameters, making it universally applicable to various noise scenarios including high-frequency wind noise and mid-frequency road noise.
3Ease of operation
If traditional equalization techniques are used, then the system is simple to implement, but they fail to account for variable noise characteristics over time, leading to inconsistent perceived tonal balance
Solution Approach 1:
The patent implements feedback by using the noise spectrum analyzer to continuously monitor the acoustic environment and feed this information back to the parametric equalizer. The system measures the actual noise floor across different frequency bands and uses this feedback to dynamically adjust the equalization parameters, ensuring consistent perceived tonal balance despite varying noise conditions. This closed-loop approach maintains reliability while managing complexity through efficient signal processing.
Data Source
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AI summary
The invention relates to a method for equalizing an audio frequency signal broadcast in a broadcast environment.Such a process includes: - an estimation (E220) of a frequency profile of a noise signal representative of background noise present in the broadcast environment, from, on the one hand, a signal captured by at least one microphone (120) implemented in the broadcast environment and, on the other hand, the audio frequency signal; - a determination (E230) of a desired frequency profile for the broadcast audio frequency signal; - a determination (E240) of a frequency acoustic mask representative, for each frequency component, of a difference between the frequency profile of the noise signal and the desired frequency profile when the frequency profiles are expressed in logarithmic units; and - an equalization (E250) of the audio frequency signal via a weighting of a spectrum of the audio frequency signal by applying a frequency weighting mask as a function of the frequency acoustic mask, delivering the equalized audio frequency signal.