Headset Analog Pre-emphasis Filter for Active Noise Compensation

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Solution Overview

Problem

Existing headsets and earphones with active noise compensation struggle to effectively address irregular level distributions in noise spectra, leading to suboptimal signal-noise ratios and noise artifacts during audio processing.

Innovation Solution

Incorporating an analog pre-emphasis filter to adjust microphone signals, followed by AD-conversion and active noise compensation, with optional digital pre-emphasis post-processing to enhance dynamic range and minimize noise artifacts, utilizing a combination of analog and digital filters to optimize signal processing and conversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If active noise compensation is implemented without pre-emphasis filtering, then the device structure remains simple, but the signal-noise ratio deteriorates and noise artifacts increase

Engineering Contradiction:

Improvesignal-noise ratioVSAvoidsignal processing structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by implementing pre-emphasis filtering on the microphone signal before it enters the active noise compensation unit. This preprocessing step boosts certain frequency components in advance, ensuring that when noise compensation is performed, the signal has already been optimized for better noise rejection. The pre-emphasis filter prepares the signal beforehand, improving the signal-noise ratio before the main processing occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary element - the pre-emphasis filter - that mediates between the microphone input and the active noise compensation unit. This intermediary component processes the signal in a way that benefits the subsequent noise compensation operation, acting as a bridge that improves overall system performance without requiring complete redesign of the entire signal processing chain.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If analog pre-emphasis filter is added before AD-conversion, then dynamic range is improved, but device complexity increases

Engineering Contradiction:

Improvedynamic rangeVSAvoidfilter structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces potential digital signal processing operations with an analog pre-emphasis filter implemented in the electrical domain before AD-conversion. This analog filtering approach achieves dynamic range improvement through continuous signal processing, avoiding the quantization limitations of digital systems and providing smoother frequency response without requiring complex digital algorithms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-generated harmful factors

If pre-emphasis filtering is applied to microphone signal, then noise artifacts are reduced, but processing time increases

Engineering Contradiction:

Improvenoise artifactsVSAvoidsignal processing time

Core Design Contradiction:

Object-generated harmful factorsVSLoss of time

Solution Approach 1:

The pre-emphasis filter performs noise artifact reduction in advance, during the analog signal processing stage before digitization. By addressing potential noise issues beforehand through analog filtering, the system prevents rather than corrects problems, eliminating the need for more time-consuming digital post-processing operations that would otherwise be required to remove noise artifacts.

Inventive Principle:

Principle #10Preliminary action

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

This approach improves the signal-noise ratio and dynamic range, reducing noise artifacts and enhancing the overall performance of active noise compensation in headsets and earphones, particularly in noise-filled environments.

Implementation Method 1

analog pre-emphasis filter to adjust microphone signals, followed by AD-conversion and active noise compensation

Methodology Applied

Scientific EffectPre-emphasis filtering: Filter (electronic)

Implementation Method 2

AD-converter for digitizing the output signal of the pre-emphasis filter

Methodology Applied

Scientific EffectAnalog-to-digital conversion:

Implementation Method 3

active noise compensation unit for performing active noise compensation based on the pre-emphasized and digitized output signal of the microphone and for outputting a counter sound signal

Methodology Applied

Scientific EffectActive noise compensation: Acoustic Absorption

Implementation Method 4

DA-converter for performing analog/digital conversion of the counter sound produced by the active noise compensation unit

Methodology Applied

Scientific EffectDigital-to-analog conversion:

Data Source

PatentUS9373317B2Headset and headphone

Publication Date: 2016.06.21 SENNHEISER ELECTRONICS GMBH & CO KG

AI summary

An earphone including at least one microphone, an analog pre-emphasis filter for pre-emphasis of the microphone signal, an AD-converter for digitizing the output signal of the pre-emphasis filter, an active noise compensation unit for performing active noise compensation based on the pre-emphasized and digitized output signal of the microphone and for outputting a counter sound signal, and a DA-converter for performing analog/digital conversion of the counter sound produced by the active noise compensation unit.