Engine Harmonic Cancellation Spurious Noise Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing engine harmonic cancellation systems face challenges in distinguishing between engine harmonics and spurious noise, particularly when one microphone is affected by external factors like airflow, leading to generation of unnatural noise artifacts.

Innovation Solution

The system employs adaptive filter circuitry with spurious microphone reading detection circuitry that correlates signals from multiple microphones, determines the presence and excessiveness of spurious noise, and modifies its operation to inhibit filter coefficient updates under certain conditions, using low pass filtering and threshold comparisons to differentiate between engine noise and spurious noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the adaptive filter continuously updates coefficients to improve engine harmonic cancellation, then the noise cancellation performance is improved, but spurious noise artifacts are generated when microphones are affected by external factors

Engineering Contradiction:

Improveengine harmonic cancellation performanceVSAvoidspurious noise artifacts

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The system uses feedback from multiple microphones to detect spurious noise conditions and adjusts adaptive filter coefficient updates accordingly. The feedback mechanism monitors microphone signals for anomalies and controls when coefficient updates should occur, preventing spurious noise artifacts while maintaining effective engine harmonic cancellation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the adaptation behavior of the adaptive filter based on real-time analysis of microphone signals. By making the coefficient update process conditional rather than continuous, the system adapts its operation to current acoustic conditions, improving reliability while avoiding spurious noise generation.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If multiple microphones are used to detect spurious noise, then the ability to distinguish engine harmonics from spurious noise is improved, but the device complexity increases

Engineering Contradiction:

Improvenoise source differentiation accuracyVSAvoidmicrophone array and processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system introduces an intermediary detection mechanism that uses correlation analysis between multiple microphone signals to identify spurious noise conditions. This intermediary process acts as a gatekeeper, determining when adaptive filter updates should proceed, thereby improving measurement precision without proportionally increasing overall system complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the adaptive filter coefficients are updated frequently to track changing noise conditions, then the noise cancellation adaptability is improved, but the system becomes sensitive to low-level spurious signals

Engineering Contradiction:

Improvenoise condition tracking capabilityVSAvoidsignal threshold discrimination accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system performs preliminary analysis of microphone signals to detect spurious noise conditions before updating adaptive filter coefficients. By checking for spurious noise artifacts in advance and conditionally preventing coefficient updates when spurious signals are detected, the system maintains adaptability to legitimate noise condition changes while avoiding sensitivity to low-level spurious signals.

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 effectively reduces unwanted noise artifacts by accurately identifying and mitigating spurious noise, ensuring effective engine harmonic cancellation even under conditions of varying noise levels and microphone sensitivity.

Implementation Method 1

correlating the signal from the first microphone with the signal from the second microphone. The correlating may include, based on the signal from the first microphone, estimating the signal from the second microphone to provide an estimated second microphone signal; and determining the difference between the estimated second microphone signal and an actual signal from the second microphone

Methodology Applied

Scientific EffectCorrelation:

Implementation Method 2

The method may include smoothing the signal from the first microphone and the signal from the second microphone. The smoothing may include low pass filtering

Methodology Applied

Scientific EffectLow pass filtering: Filter (electronic)

Data Source

PatentEP2545545B1Engine audio harmonic cancellation system and operating method thereof

Publication Date: 2016.05.11 BOSE CORP

Figure 1~2
Figure 3~4
Figure 5~6

AI summary

A system for correcting erroneous microphone readings in a vehicle engine harmonic cancellation (EHC) system. A method for operating an engine harmonic cancelling system, includes receiving, from a first microphone at a first location in a vehicle cabin, a signal representative of noise in the vehicle cabin; receiving, from a second microphone at a second location in the vehicle cabin, a signal representative of noise in the vehicle cabin; and correlating the signal from the first microphone with the signal from the second microphone.