Vehicle Engine Noise Masking via Psychoacoustic Signal Generation
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Solution Overview
Problem
Existing methods are inadequate for reducing specific noise frequencies from rotary equipment in vehicle engines, particularly those above 300 Hz, which cannot be effectively canceled by active noise control or standard damping/insulation techniques.
Innovation Solution
A method and system that generates a masking noise with frequencies surrounding the specific noise frequency, determined by engine input conditions, to reduce its prominence through psychoacoustic principles, using microphones to record sound spectra and an electronic control unit with a digital signal processor and noise generator to produce band-pass filtered noise signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active noise control is used to cancel specific noise frequencies, then low frequency noise (below 300 Hz) can be reduced, but it cannot be applied to specific noise frequencies above 300 Hz
Solution Approach 1:
The patent changes the approach from active noise control (phase cancellation) to psychoacoustic masking. Instead of attempting to cancel the specific noise frequency directly, the system generates a masking noise with a broader frequency spectrum that encompasses the specific noise frequency, thereby reducing its perceived prominence through psychoacoustic principles.
Solution Approach 2:
The patent replaces the mechanical/physical approach of active noise control with a psychoacoustic approach. Rather than using physical phase cancellation which is frequency-limited, the system uses perceived sound masking that can be applied across a broader frequency range including frequencies above 300 Hz.
2Object-affected harmful factors
If standard sound absorbing or noise reducing means are used, then some noise can be dampened, but they are ineffective for specific noise frequencies from rotary equipment
Solution Approach 1:
The patent replaces passive mechanical noise reduction methods (resonators, insulation) with an active psychoacoustic masking system. The electronic noise generation and playback system can dynamically adapt to specific noise frequencies that passive methods cannot effectively address.
Solution Approach 2:
The patent implements a dynamic noise masking system that continuously monitors engine operating conditions (rpm, torque, temperature, pressure) and adjusts the masking noise characteristics in real-time. This dynamic adaptation allows the system to effectively track and mask specific noise frequencies that vary with engine operation, unlike static passive noise reduction methods.
3Object-affected harmful factors
If a masking noise is generated to reduce specific noise frequency prominence, then the specific frequency becomes less noticeable, but the system complexity increases with multiple sensors and processing components
Solution Approach 1:
The patent integrates multiple functions into a unified noise masking system. The same system that monitors engine parameters for performance optimization also uses these parameters to generate and control the masking noise. The audio playback system serves both entertainment and noise masking purposes, reducing overall system complexity.
Solution Approach 2:
The system uses the engine's own operational parameters (rpm, torque, temperature, pressure) that are already being monitored for engine management to control the masking noise generation. This self-service approach eliminates the need for separate sensing and control systems, as the existing engine management data is repurposed for noise masking control.
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 masking noise system effectively reduces the perceived prominence of specific noise frequencies by matching their amplitude and frequency to ambient broadband sounds, maintaining an appealing engine sound while masking unwanted tones.
Implementation Method 1
A masking noise is output having frequencies surrounding the specific noise frequency in a first bandwidth, wherein the specific noise frequency is perceived to be less prominent than otherwise
Implementation Method 2
A first band-pass filter is provided having a first pass band centered on the first frequency
Implementation Method 3
An amplifier is provided having an input arranged to receive the first band-pass filtered noise signal and an output arranged to output a masking noise
Data Source
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AI summary
The invention relates to a method for masking noise originating from rotary equipment in a vehicle engine. The method comprises: - checking if one or more engine input conditions fulfil engine input condition threshold values, wherein, if said one or more engine input conditions fulfil said engine input conditions threshold values, - outputting a first masking noise from at least one speaker (6), wherein the first masking noise comprises a first central frequency, a first predetermined bandwidth and a first amplitude, wherein the first central frequency and the first amplitude is determined by said input conditions. The invention also relates to a system (1) for masking noise originating from rotary equipment in a vehicle engine.