Vehicle Woofer Infinite Baffle and Bass-Compatible Speaker Arrangement

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Solution Overview

Problem

Conventional woofer mounting in vehicles often results in suboptimal bass-range sound production due to packaging constraints and resonance issues, as large speakers are typically housed in sealed enclosures that do not effectively transmit low-frequency sound to the passenger compartment.

Innovation Solution

A woofer with an infinite baffle configuration, where the front side is in fluid communication with the passenger compartment and the back side is open to the environment, combined with a bass-compatible speaker, and a controller that redistributes bass output from the woofer to the bass-compatible speaker based on vehicle speed and sound pressure levels to enhance bass-range sound and reduce resonance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a woofer is mounted with an infinite baffle configuration (back side open to environment), then bass-range sound quality is improved, but undesirable noise emission outside the vehicle increases

Engineering Contradiction:
Improvebass-range sound qualityVSAvoidundesirable noise emission
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The system dynamically switches between two woofer configurations based on vehicle speed: at low speeds, the woofer operates in sealed enclosure mode to minimize external noise emission; at high speeds, the woofer operates with infinite baffle configuration to maximize bass-range sound quality inside the vehicle. This dynamic adaptation resolves the contradiction by allowing both configurations to be used at appropriate times.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the acoustic parameter of the woofer environment from sealed to open based on operating conditions. By controlling the enclosure state of the woofer back side according to vehicle speed, the system optimizes bass sound quality while minimizing external noise emission at different operating points.

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If a woofer is mounted in a sealed enclosure, then undesirable noise emission outside the vehicle is reduced, but bass-range sound quality deteriorates

Engineering Contradiction:
Improveundesirable noise emissionVSAvoidbass-range sound quality
Core Design Contradiction:
Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The system dynamically switches between sealed and open woofer configurations based on vehicle speed. At high speeds where external noise is already high, the sealed enclosure is used to prevent additional noise emission while the infinite baffle configuration is used at low speeds to optimize bass sound quality, resolving the trade-off dynamically.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The acoustic parameter of the woofer environment is changed from sealed to open state based on vehicle speed conditions. This parameter change allows the system to minimize noise emission when necessary while maximizing bass sound quality when the vehicle is stationary or moving slowly.

Inventive Principle:
Principle #35Parameter changes

3Object-generated harmful factors

If bass output is redistributed from woofer to bass-compatible speaker at low speeds, then undesirable noise emission is minimized, but bass-range sound output may be reduced

Engineering Contradiction:
Improveundesirable noise emissionVSAvoidbass-range sound output
Core Design Contradiction:
Object-generated harmful factorsVSQuantity of substance

Solution Approach 1:

The controller continuously monitors vehicle speed and sound pressure levels, and dynamically adjusts the distribution of bass output between the woofer and bass-compatible speaker. This feedback mechanism ensures that bass output is redistributed to minimize external noise emission at low speeds while maintaining adequate bass-range sound output through coordinated control of both speakers.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The bass-compatible speaker serves multiple functions: it provides bass-range sound output and also acts as a noise control mechanism by redistributing bass away from the woofer at low speeds. This multi-functionality allows the system to maintain bass output while minimizing undesirable noise emission.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Ease of manufacture

If woofer size is increased to improve bass-range sound, then bass sound quality is improved, but packaging constraints are violated

Engineering Contradiction:
Improvebass-range sound qualityVSAvoidspeaker enclosure volume
Core Design Contradiction:
Ease of manufactureVSVolume of moving object

Solution Approach 1:

The system merges the functions of a large dedicated bass speaker with a smaller bass-compatible speaker. By combining the output of both speakers, the system achieves adequate bass-range sound quality without requiring a large woofer that would violate packaging constraints, thus resolving the contradiction between sound quality and space requirements.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Instead of using a single large woofer, the system uses a smaller woofer combined with a bass-compatible speaker that replicates or supplements the bass output. This copying approach allows the system to achieve similar bass sound quality with smaller components that fit within packaging constraints.

Inventive Principle:
Principle #26Copying

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 improves bass-range sound quality by reducing resonance and vibrations, maintaining sound pressure levels within the vehicle, and minimizing undesirable noise emission outside the vehicle, especially at low speeds.

Implementation Method 1

The loudspeaker driver has a vibratile surface for generating sound pressure waves in response to electrical stimulation

Methodology Applied
Scientific EffectSound pressure waves: Sound

Implementation Method 2

A loudspeaker driver is disposed in the vehicle body outside the passenger compartment. The loudspeaker driver has a vibratile surface for generating sound pressure waves in response to electrical stimulation

Methodology Applied
Scientific EffectElectrical stimulation to sound conversion:

Implementation Method 3

A controller is in communication with the woofer and the bass-compatible speaker and is programmed to redistribute at least a portion of the required bass-range sound output away from the woofer to the bass-compatible speaker

Methodology Applied
Scientific EffectAcoustic energy redistribution:

Data Source

PatentEP3251379B1Vehicle speaker arrangement
Publication Date: 2020.04.15 HARMAN INT IND INC
  • EP3251379B1 patent drawingFigure 1~1A
  • EP3251379B1 patent drawingFigure 2
  • EP3251379B1 patent drawingFigure 3~5

AI summary

An audio system for a vehicle is provided with a woofer speaker having a front side for producing a required bass-range acoustic output in a passenger compartment of the vehicle and a back side having an infinite baffle. The audio system includes a bass-compatible speaker disposed in the passenger compartment of the vehicle. A controller is in communication with the woofer and the bass-compatible speaker and is programmed to distribute the required bass-range sound output to the woofer and the bass-compatible speaker based on at least one of a vehicle speed and a sound output level of the audio system.