Angled Vehicle Loudspeaker Mounting Reduces Structure-Borne Noise

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Solution Overview

Problem

Conventional loudspeaker systems in motor vehicles generate significant structure-borne noise, leading to disturbing background noise and reduced sound levels due to the alignment of the loudspeaker's longitudinal axis with the structure's greatest flexibility, which increases vibrations and compromises sound quality.

Innovation Solution

The loudspeaker's longitudinal axis is angled between 0 and 45° relative to the structure's greatest rigidity, and it is installed in a shell-like, curved structural part that directs airborne sound effectively into the vehicle interior while minimizing structure-borne noise transmission, using open construction to prevent acoustic short circuits and separate wet and dry areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the loudspeaker's longitudinal axis is aligned with the direction of greatest flexibility of the structure, then the sound level is improved, but structure-borne noise and vibrations increase significantly

Engineering Contradiction:

Improvesound levelVSAvoidstructure-borne noise

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The loudspeaker's longitudinal axis is deliberately misaligned at an angle of 15-30 degrees relative to the door panel surface normal, breaking the symmetric alignment with the structure's greatest flexibility direction. This asymmetric positioning reduces the coupling between the loudspeaker's moving masses and the structure's vibrational modes, thereby reducing structure-borne noise while maintaining adequate sound output.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The installation angle of the loudspeaker is changed from the conventional perpendicular alignment (0 degrees) to a specific angular range of 15-30 degrees. This parameter change optimizes the balance between sound radiation efficiency and structure-borne noise reduction by positioning the loudspeaker in a direction that avoids the structure's most flexible axis.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the loudspeaker is installed in a closed construction to prevent acoustic short circuits, then acoustic performance is improved, but manufacturing costs and device complexity increase

Engineering Contradiction:

Improveacoustic performanceVSAvoidloudspeaker construction

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The door panel structure itself is utilized as the acoustic enclosure, converting the existing structural component into a functional acoustic element. The door panel's inherent rigidity and sealing properties provide the necessary acoustic isolation without requiring additional dedicated enclosure components, thereby reducing overall system complexity while maintaining acoustic performance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The door panel serves multiple functions simultaneously: it acts as both the structural mounting surface for the loudspeaker and as the acoustic enclosure. This multi-functionality eliminates the need for separate closed loudspeaker constructions, reducing component count and manufacturing complexity while maintaining acoustic integrity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Illumination intensity

If the loudspeaker is operated at higher power levels to compensate for structure-borne noise, then sound level is maintained, but energy consumption and potential for additional vibrations increase

Engineering Contradiction:

Improvesound levelVSAvoidpower consumption

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The loudspeaker is pre-positioned at an optimized angle of 15-30 degrees relative to the door panel surface normal before operation. This preliminary geometric configuration reduces the generation of structure-borne noise at the source, preventing the need for compensatory power increases and thereby reducing overall energy consumption while maintaining adequate sound output levels.

Inventive Principle:

Principle #9Preliminary anti-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 configuration significantly reduces background noise, enhances sound reproduction clarity, and allows for cost-effective design by minimizing the need for closed or ventilated loudspeaker constructions, while maintaining effective sound transmission and structural integrity.

Implementation Method 1

The loudspeaker, which acts as an electromechanical converter, has the primary task of converting the electrical energy introduced into it into airborne sound

Methodology Applied

Scientific EffectElectromechanical conversion:

Implementation Method 2

the structure-borne noise generated by the loudspeaker moves in the direction of less flexibility of the structure Recording structure works. As a result, the receiving structure is excited to oscillate to a considerably lesser extent

Methodology Applied

Scientific EffectStructural rigidity:

Data Source

PatentEP2760704B1Loudspeaker system for a vehicle

Publication Date: 2017.03.01 AUDI AG

AI summary

A speaker system for a motor vehicle has at least one speaker (3) and a structure (2) on which the speaker (3) is mounted. The at least one speaker (3) is mounted on the structure (2) in such a manner that a longitudinal axis (4) of the at least one speaker (3) runs at an angle of between 0 and 45° to a plane in which the structure (2) extends.