Loudspeaker Waveguide with Equal Sound Path Lengths

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Solution Overview

Problem

Conventional loudspeakers often waste sound energy by directing it towards non-listener areas and causing interference with adjacent speakers, as their sound waves radiate uniformly in all directions without controlled propagation.

Innovation Solution

The implementation of a loudspeaker waveguide with equal sound path lengths in all directions, creating a controlled sound output shape that focuses sound waves towards listeners by using a waveguide with a sinusoidal inlet and a rectangular outlet, ensuring coherent sound propagation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If sound waves radiate uniformly in all directions from the driver unit, then the sound coverage area is maximized, but sound energy is wasted in non-listener areas and causes interference with adjacent loudspeakers

Engineering Contradiction:
Improvesound energy wasteVSAvoidsound coverage area
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The waveguide extracts and separates sound energy in different directions. The vertical baffle within the waveguide physically blocks and redirects upward-traveling sound waves, preventing them from reaching the ceiling and being wasted, while allowing forward-traveling sound waves to pass through to the listening area.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The waveguide introduces asymmetric sound propagation control by placing a vertical baffle that differentially affects sound waves traveling in different directions. Sound waves traveling upward are blocked and redirected, while sound waves traveling forward are allowed to pass, creating asymmetric energy distribution that reduces waste without compromising forward coverage.

Inventive Principle:
Principle #4Asymmetry

2Object-generated harmful factors

If sound waves propagate without controlled direction, then the loudspeaker structure is simple, but sound waves cause interference with adjacent loudspeakers in a directional array

Engineering Contradiction:
Improvesound interferenceVSAvoidwaveguide structure
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The waveguide is segmented into distinct functional regions: an inlet region receiving sound from the driver, a propagation region with a vertical baffle that divides and controls sound paths, and an outlet region where controlled sound waves emerge. This segmentation allows independent optimization of each region to manage interference while maintaining overall simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The vertical baffle acts as an intermediary element within the waveguide that mediates sound wave propagation. It intercepts upward-traveling sound waves and redirects them forward, serving as a simple passive structure that effectively controls interference without requiring complex active components or multiple moving parts.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Power

If the waveguide cross-sectional area expands rapidly, then the sound output impedance is reduced, but the waveguide length increases and creates phase delays

Engineering Contradiction:
Improvesound output impedanceVSAvoidwaveguide length
Core Design Contradiction:
PowerVSLength of moving object

Solution Approach 1:

The waveguide employs a dynamic cross-sectional area expansion profile rather than a fixed geometric shape. The cross-sectional area increases gradually along the propagation path, allowing the waveguide to adaptively match acoustic impedance transitions while maintaining a compact overall length and avoiding excessive phase delays.

Inventive Principle:
Principle #15Dynamics

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 design enhances sound propagation control, reducing waste and improving sound production efficiency by directing sound waves effectively towards the intended listening area.

Implementation Method 1

a waveguide (108) configured to control propagation of sound from the driver unit (202) to create a shape of sound output

Methodology Applied
Scientific EffectAcoustic wave propagation: Sound

Implementation Method 2

providing substantially equal sound path lengths to create a flat and/or curved wave front from the exit of a compression driver

Methodology Applied
Scientific EffectWave front formation: Sound

Data Source

PatentEP3507991B1Loudspeaker acoustic waveguide
Publication Date: 2024.10.09 HARMAN INT IND INC
  • EP3507991B1 patent drawingFigure 1A~1B
  • EP3507991B1 patent drawingFigure 2
  • EP3507991B1 patent drawingFigure 3

AI summary

Examples are disclosed for a waveguide for a loudspeaker, the waveguide including a first and second outer shell coupled to one another, and a first and second inner shell coupled to one another and positioned within an air gap between the first and second outer shells, a plurality of sound paths being formed between an exterior surface of the first inner shell and an interior surface of the first outer shell and between an exterior surface of the second inner shell and an interior surface of the second outer shell, each of the plurality of sound paths having an equal path length in a plurality of planes.