Earphone Acoustic Cavity Traps Backwave Sound
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Solution Overview
Problem
Earphones and headphones suffer from backwave distortion effects due to interactions between forward and backward sound waves, leading to reduced audio quality and definition.
Innovation Solution
A novel configuration of the earphone or headphone device featuring a housing with a perpetual self-feeding closed-loop acoustic cavity that traps and circulates backwave sound waves, preventing them from interacting with forward-generated waves, using a spiral, helix, or horn-like structure to create a closed-loop waveguide channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional acoustic cavity is used in earphone/headphone, then the device structure is simple, but backwave distortion occurs due to interaction between forward and backward sound waves
Solution Approach 1:
The acoustic cavity is segmented into multiple regions: a forward wave propagation path and a separate backward wave circulation path. The backward wave path is further divided into distinct segments including a backward wave inlet, circulation path, and outlet, allowing backward waves to be isolated and circulated separately from forward waves, eliminating distortion while maintaining manufacturing simplicity
Solution Approach 2:
The harmful backward sound waves are extracted from the main forward wave path and directed into a separate circulation loop. By taking out the backward waves through a dedicated inlet and routing them through a circulation path with outlet, the interference between forward and backward waves is eliminated, resolving the backwave distortion problem
2Device complexity
If forward and backward sound waves are allowed to interact in the acoustic cavity, then the device structure is simple, but audio definition and separation deteriorate
Solution Approach 1:
The acoustic cavity is divided into functionally distinct segments: a forward wave channel and a backward wave circulation system. This segmentation ensures that forward waves traveling to the listener are separated from backward waves circulating in the dedicated loop, preventing phase cancellation and preserving audio definition and separation
Solution Approach 2:
The backward wave circulation path acts as an intermediary structure that captures and redirects backward waves away from the forward wave path. This intermediary circulation loop with inlet and outlet serves as a mediator to prevent direct interaction between forward and backward waves, maintaining audio quality
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
Significantly reduces backwave distortion, enhancing sound quality by ensuring forward and backward waves propagate along spatially separated paths, thereby improving audio definition and separation.
Implementation Method 1
backward generated sound waves are those to be prevented from reaching the output of the earphone or headphone device
Implementation Method 2
the acoustic cavity is configured according to the invention to define a perpetual self-feeding closed-loop structure for backwave sound originated at the driver site, such that the backwave sound is trapped and caused to circulate in the closed-loop structure
Data Source
AI summary
An earphone/headphone device, and a housing for such device are presented. The housing has proximal and distal ends defining respectively, a proximal closed-end portion and a distal open-end portion of the device, and comprises a sound source site for mounting a sound source in this site inside the housing, and an acoustic cavity extending from a back side of the sound source site and the proximal end portion of the housing. The acoustic cavity is configured to define a perpetual self-feeding closed-loop structure for propagation of backwave sound originated at the sound source site, such that the backwave sound is trapped and circulates in the closed-loop structure.