Externally Ducted Loudspeaker Pressure Equalization in Vehicles

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Solution Overview

Problem

Vehicle audio systems face challenges in reproducing low-frequency sound due to practical limitations in speaker enclosure size and the need to protect loudspeakers from high pressure differentials between the vehicle interior and exterior.

Innovation Solution

The implementation of a ducted vehicle loudspeaker system that includes an acoustic conduit to acoustically couple the loudspeaker to the outside of the vehicle, along with an isolation valve to protect the loudspeaker from pressure differentials by adjusting the audio signal or isolating the loudspeaker.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a loudspeaker is coupled to the exterior of the vehicle to act as an infinite baffle for low frequency reproduction, then acoustic performance is improved, but the loudspeaker is exposed to high pressure differentials that may cause damage

Engineering Contradiction:

Improveloudspeaker performanceVSAvoidpressure differential

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A pressure equalization valve is introduced as an intermediary component between the loudspeaker enclosure and the external environment. This valve mediates the pressure differential by opening to equalize pressure when it exceeds a threshold, thereby protecting the loudspeaker from damage while allowing the system to benefit from external coupling for acoustic performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically changes the pressure parameter within the loudspeaker enclosure by using the pressure equalization valve to open or close based on pressure differential conditions. This parameter change allows the system to adapt to varying external pressure conditions, maintaining both acoustic performance and protecting against damage.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If sealed enclosures are used for loudspeaker mounting, then acoustic performance is improved, but the enclosure requires too much volume to be practical for vehicular applications

Engineering Contradiction:

Improveacoustic performanceVSAvoidenclosure volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The system segments the acoustic space by using a duct or conduit that extends from the loudspeaker enclosure to an external opening in the vehicle body. This segmentation allows the enclosure to be smaller while still benefiting from the acoustic properties of a larger volume through the external duct connection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system transitions from a three-dimensional enclosed volume to a one-dimensional duct connection that extends to the external environment. This dimensional change allows the system to achieve effective acoustic volume without requiring a large internal enclosure space, making it practical for vehicular applications.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Power

If conventional ported box structures are used, then output from the port is improved, but significant enclosure dimensions are required

Engineering Contradiction:

Improveport outputVSAvoidenclosure dimensions

Core Design Contradiction:

PowerVSVolume of stationary object

Solution Approach 1:

The external duct or conduit acts as an intermediary that extends the port function outside the vehicle enclosure. This allows the port to achieve significant output without requiring a large internal enclosure volume, as the acoustic path extends externally where space is not constrained by the vehicle interior.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively mitigates the adverse effects of pressure differentials on loudspeaker performance and longevity, ensuring optimal acoustic response and preventing potential damage to the loudspeaker.

Implementation Method 1

an acoustic conduit configured to acoustically couple a sound-producing surface of an acoustic transducer

Methodology Applied

Scientific EffectAcoustic coupling: Sound

Implementation Method 2

protecting the loudspeaker from high pressure differentials between the outside atmosphere and inside the vehicle

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 3

a pressure equalizing component configured to equalize pressure between opposing sides of a diaphragm of the acoustic transducer

Methodology Applied

Scientific EffectPressure equalization: Pressure Gradient

Data Source

PatentUS12330566B2Pressure control in externally ducted loudspeakers

Publication Date: 2025.06.17 DR ING H C F PORSCHE AG

AI summary

A vehicle audio system includes a loudspeaker configured to be acoustically coupled to an interior of a vehicle and to be ducted to an exterior of the vehicle as well as a controller coupled to the loudspeaker. The controller is configured to (i) detect one or more vehicle operating parameters of the vehicle that would result in a pressure differential condition between the interior and the exterior, and (ii) adjust a gain of an audio signal provided to the loudspeaker in response to detecting the vehicle operating parameters.