Headphone Equalization Filter via Spatial Averaging

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Solution Overview

Problem

Existing methods for determining acoustic parameters of headphones are inadequate, leading to variations in frequency response due to diverse headphone types, designs, and electro-acoustic transducer technologies, resulting in inconsistent spectral balance between headphones and studio mixing monitors.

Innovation Solution

A method of determining equalization filter parameters by measuring amplitude response values at multiple locations along a reference plane parallel to the sound emitting side of the headphone earpiece, using a weighted average to account for nonlinearities and distortions, and applying these measurements to generate a composite response curve for accurate frequency correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single measurement location is used to determine frequency response, then the measurement process is simple and quick, but the frequency response curve does not accurately represent the acoustic output across different positions

Engineering Contradiction:
Improvefrequency response accuracyVSAvoidmeasurement process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measurement process is segmented into multiple discrete measurement locations (at least three different positions) around the headphone earpiece. Each location provides a separate frequency response measurement, and these segmented measurements are then combined through spatial averaging to create a comprehensive frequency response curve that represents the acoustic output across different positions.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If multiple measurement locations are used to capture spatial variations, then frequency response accuracy improves, but the measurement time and process complexity increase

Engineering Contradiction:
Improveamplitude response accuracyVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

Multiple amplitude response measurements taken at different spatial locations are merged through spatial averaging. The frequency response curves from each measurement location are combined mathematically (typically by averaging the magnitude responses across all locations) to produce a single composite frequency response curve that represents the overall acoustic characteristics of the headphone earpiece.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If spatial averaging is applied to combine measurements, then a representative frequency response curve is obtained, but the complexity of data processing increases

Engineering Contradiction:
Improvefrequency response representativenessVSAvoiddata processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measurement system is designed to be universally applicable to different headphone types and electro-acoustic transducer technologies. The same spatial averaging procedure can be applied across various headphone designs (circumaural, supra-aural, in-ear, etc.) to obtain representative frequency response curves, making the method universally useful for characterizing diverse acoustic devices.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3809714B1Method of and apparatus for determining an equalization filter
Publication Date: 2025.09.10 SONARWORKS SIA
  • EP3809714B1 patent drawingFigure 1
  • EP3809714B1 patent drawingFigure 2a~2b
  • EP3809714B1 patent drawingFigure 3

AI summary

A method for determining equalization filter parameters for a headphone, the method includes determining a composite response curve based on an average of amplitude response values measured from a plurality of measurement locations, the plurality of measurement locations, in cumulative, substantially spanning at least the headphone transducer, and determining the equalization filter parameters based on the determined composite response curve.