Electronic Hearing Protector Quadrant Sound Localization
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Solution Overview
Problem
Existing electronic hearing protectors face challenges in accurately localizing sound sources in the horizontal plane, particularly distinguishing between front and back, due to limitations in duplex theory and individual variations in head-related transfer functions (HRTFs), leading to ambiguity in sound localization.
Innovation Solution
An electronic hearing protector with ear cup assemblies featuring front and rear microphones, a processor, and filters that provide a high-frequency roll-off and notch filter to enhance sound localization by summing and processing signals to simulate head-related transfer functions, allowing for improved front-to-back sound localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If duplex theory is used for sound localization, then left-right localization is achieved, but front-back localization remains ambiguous
Solution Approach 1:
The patent transitions from two-dimensional horizontal plane localization (left-right only) to three-dimensional localization by incorporating vertical dimension information through spectral cues. The filter bank analyzes frequency-specific energy distribution across multiple dimensions, enabling front-back discrimination by detecting spectral patterns that correspond to different elevation angles and head orientations.
Solution Approach 2:
The patent introduces spectral filtering as an intermediary mechanism between the raw binaural signals and the localization decision. The filter bank acts as a mediator that extracts spectral cues from the signals, which then inform the quadrant determination algorithm about front-back orientation, effectively bridging the gap left by duplex theory.
2Measurement precision
If HRTFs are used for spatial sound reproduction, then spectral cues are provided, but individual variations cause localization inaccuracies
Solution Approach 1:
Instead of applying a single global HRTF model to all users, the patent implements local quality by analyzing spectral patterns specific to each user's head and ear geometry. The filter bank extracts spectral cues that are inherently adapted to the individual's anatomy, providing localized spectral characteristics that improve localization accuracy for that specific user without requiring a custom HRTF model.
Solution Approach 2:
The system performs self-adjustment by automatically adapting to each user's unique spectral characteristics through the filter bank analysis. Rather than requiring manual calibration or selection from pre-defined HRTF sets, the system self-calibrates by detecting the user's spectral patterns and using those to determine sound source quadrants, making the solution universally adaptable without individual customization.
3Measurement precision
If high-resolution angle distinction is implemented, then precise localization is achieved, but computational complexity increases
Solution Approach 1:
The patent applies partial action by implementing quadrant-level localization (four discrete regions) rather than continuous high-resolution angle distinction. This provides sufficient localization precision for practical applications while dramatically reducing computational complexity compared to full high-resolution spatial audio processing. The filter bank analyzes spectral patterns at a coarse granularity level that is adequate for quadrant determination.
Solution Approach 2:
The patent segments the horizontal plane into four distinct quadrants and processes spectral cues separately for each quadrant determination. The filter bank divides the frequency spectrum into multiple bands, and the system determines which quadrant contains the sound source by comparing spectral patterns across these segmented regions, reducing overall computational complexity through systematic segmentation.
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 provides enhanced audio cues for accurate sound localization, specifically resolving the ambiguity between front and back sound sources by leveraging spectral differences and simulating HRTFs, thereby improving the wearer's ability to determine sound source positions in the horizontal plane.
Implementation Method 1
A filter receives and filters the rear channel signal, and has a cut-off frequency value that provides a high-frequency roll-off
Implementation Method 2
a notch at a notch filter frequency value that is less than the cut-off frequency value
Implementation Method 3
Spectral shaping of sounds due to reflection and refraction around and along the head, torso, and outer ear (pinna) may be used to infer information about the location of the source
Implementation Method 4
a front exterior microphone that provides a front microphone signal and a rear exterior microphone that provides a rear microphone signal
Implementation Method 5
A first signal indicative of the front channel signal and a second signal indicative of the filtered signal are summed, and a signal indicative of the resultant sum is provided to a transducer
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
An electronic hearing protector includes an ear cup assembly comprising a front exterior microphone that provides a front microphone signal and a rear exterior microphone that provides a rear microphone signal. A processor receives and digitizes the front microphone signal and the rear microphone signal, and provides a front channel signal and a rear channel signal indicative thereof respectively. A filter receives the rear channel signal and has a cut-off frequency value that provides a high-frequency roll-off and a notch at a notch filter frequency value that is less than the cut-off frequency value, where the filter provides a filtered signal. A first signal indicative of the front channel signal and a second signal indicative of the filtered signal are summed, and a signal indicative of the summed signal is provided to a speaker within the ear cup that provides an audio signal within the first ear cup indicative of the summed signal.