ITE ANR Earphone Microphone Placement for Stability and Comfort

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Solution Overview

Problem

In-the-ear (ITE) earphones with automatic noise reduction (ANR) technology face design compromises between noise reduction and user comfort, with larger nozzles providing better noise reduction but being uncomfortable and smaller nozzles leading to instability and electronic noise issues.

Innovation Solution

Placing a micro electro mechanical sensor (MEMS) microphone within the ear-insertion port, oriented transverse to sound, allows for improved noise measurement and feedback loop stability, using a smaller nozzle with a cross-sectional area of approximately 3.3 square millimeters and an effective length of 10 millimeters, which maintains comfort and ANR performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a larger nozzle cross-sectional area is used to improve ANR performance, then noise reduction is enhanced, but user comfort deteriorates

Engineering Contradiction:

ImproveANR performanceVSAvoiduser comfort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces the traditional large mechanical nozzle structure with a smaller nozzle combined with an electronic feedback system using a MEMS microphone and active noise reduction circuitry. This substitution allows the system to achieve effective noise cancellation through electronic control rather than relying solely on passive acoustic design, thereby maintaining ANR performance while improving comfort.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If a smaller nozzle cross-sectional area is used to improve user comfort, then comfort is enhanced, but ANR stability deteriorates

Engineering Contradiction:

Improveuser comfortVSAvoidANR feedback loop stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback mechanism by placing a MEMS microphone within the nozzle to directly sense acoustic conditions in the ear canal. This feedback signal is fed to the ANR circuitry, which adjusts the anti-noise signal in real-time, thereby stabilizing the feedback loop and preventing high-pitched squeals even with a smaller nozzle cross-sectional area.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces reliance on passive acoustic stability (which requires large nozzles) with an active electronic control system. The MEMS microphone and digital signal processing substitute for the mechanical acoustic design, enabling stable ANR operation with smaller, more comfortable nozzle dimensions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If a probe tube is added to extend between the microphone and ear cavity to improve ANR measurement, then measurement accuracy is enhanced, but device complexity and electronic noise increase

Engineering Contradiction:

Improveacoustic measurement accuracyVSAvoidcircuitry complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the microphone from the front acoustic volume and relocates it directly into the nozzle, eliminating the need for a separate probe tube extension. This repositioning allows the MEMS microphone to directly sense ear canal acoustics through the nozzle, achieving accurate measurement without adding the complexity and noise associated with extended probe tubes and additional circuitry.

Inventive Principle:

Principle #2Taking out (Extraction)

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 configuration enhances user comfort without sacrificing ANR performance, reduces the likelihood of high-pitched squeals, and maintains ANR feedback loop stability, providing a superior listening experience.

Implementation Method 1

Placing the microphone in the port allows the microphone to more closely measure or sense what is happening in the ear canal

Methodology Applied

Scientific EffectAcoustic energy detection: Sound

Implementation Method 2

the ANR circuitry attempts to cancel or suppress it by driving the ear speakers to vibrate in opposition to the undesired sounds

Methodology Applied

Scientific EffectAcoustic cancellation: Interference

Data Source

PatentUS10021478B2In-the-ear automatic-noise-reduction devices, assemblies, components, and methods

Publication Date: 2018.07.10 AVNERA CORP

AI summary

Automatic noise-reduction (ANR) headsets include circuitry that cancels or suppress undesired noises. Recent years have seen the emergence of in-the-ear (ITE) earphones that incorporate ANR technology; however, designing them to function well usually entails many design tradeoffs, such as using larger ear nozzles that are uncomfortable to obtain desired noise reduction or that require added structures to hold the earphones to a user ear. To avoid these tradeoffs, the present inventors devised, among other things, an exemplary ITE ANR earphone that places its error measurement microphone in the ear nozzle that connects the driver front acoustic volume to a user ear canal. This placement allows use of a narrower more comfortable ear nozzle without compromising noise reduction and without requiring added holding structures. Moreover, the narrower ear nozzle also lowers the likelihood that the ANR circuitry will become unstable and produce undesirable noise.