Adaptive Sound Masking Filter for Room Acoustic Correction

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Solution Overview

Problem

Existing sound masking systems face challenges in automatically adjusting the ideal masking noise spectrum to suit diverse environments, such as varying room sizes and ambient noise levels, especially in larger spaces where manual adjustments are laborious and often yield poor results.

Innovation Solution

A sound masking system that includes a white noise generator and a dynamically determined mask filter, which corrects the acoustical response of the room and ambient noise to produce a target masking noise, using a method involving acoustical measurements and signal processing to filter the white noise and achieve the desired noise spectrum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual adjustment by 1 octave or 1/3 octave equalization is used, then the system is simple to operate, but the manufacturing precision of the masking noise spectrum is insufficient for larger environments

Engineering Contradiction:

Improvemanual adjustment simplicityVSAvoidmasking noise spectrum precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces manual mechanical adjustment of equalization filters with an automated digital signal processing system. A measurement microphone captures the actual acoustical response, and a processor automatically calculates and applies the necessary corrections to achieve the target masking noise spectrum, eliminating the need for laborious manual trial-and-error adjustment while significantly improving precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-adjustment by automatically measuring its own acoustical response through the measurement microphone and computing the required corrections. The processor generates the appropriate filter settings based on the measured response and target spectrum, allowing the system to self-optimize without external manual intervention.

Inventive Principle:

Principle #25Self-service

2Manufacturing precision

If automated adjustment systems are implemented, then the manufacturing precision of masking noise spectrum is improved, but the device complexity increases

Engineering Contradiction:

Improvemasking noise spectrum precisionVSAvoidsystem complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a measurement microphone as an intermediary device that captures the acoustical response and provides data to the processor. This intermediary enables the automated measurement and adjustment process, bridging the gap between the physical acoustical environment and the digital signal processing system without requiring complex sensor arrays or multiple measurement devices.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The processing system serves multiple functions: it analyzes the measured acoustical response, calculates the required corrections, generates the appropriate filter settings, and controls the masking noise generation. This multi-functional approach consolidates what could be separate complex subsystems into a single integrated unit, reducing overall system complexity while maintaining high precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If manual preset voltage adjustment is used, then the device complexity is low, but the adaptability to different room conditions and ambient noise levels is poor

Engineering Contradiction:

Improvesystem complexityVSAvoidadaptability to room conditions

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The system implements feedback by continuously measuring the actual acoustical response and ambient noise levels through the measurement microphone and using this information to automatically adjust the masking noise spectrum. The processor compares the measured response against the target spectrum and dynamically modifies the output to achieve optimal speech privacy adaptation to each specific room condition.

Inventive Principle:

Principle #23Feedback

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 system automatically generates a target masking noise spectrum that optimizes speech privacy by accounting for room acoustics and ambient noise, providing precise noise control across multiple rooms and environments.

Implementation Method 1

a white noise generator and a mask filter, wherein the mask filter is automatically determined according to a correction of an acoustical response of the room, obtained when loudspeakers emit a white noise generated by the white noise generator

Methodology Applied

Scientific EffectWhite noise generation:

Implementation Method 2

the mask filter once determined filtrating a white noise generated by the white noise generator to yield the target masking noise emitted in the room

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Implementation Method 3

obtained when loudspeakers emit a white noise generated by the white noise generator

Methodology Applied

Scientific EffectElectroacoustic transduction:

Data Source

PatentUS7460675B2Auto-adjusting sound masking system and method

Publication Date: 2008.12.02 SOFT DB

AI summary

A system and method for generating a masking noise level and spectrum automatically adjusted to obtain a target masking noise spectrum in a room. The system comprises a white noise generator and a mask filter automatically determined according to a correction of an acoustical response of the room and to the target masking noise corrected by an ambient noise.