Open-End Headphone Acoustic Delay for Noise Isolation
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Solution Overview
Problem
Headphones and earphones that are acoustically not sealed lack passive noise dampening capabilities but offer better comfort and audio quality, while sealed ones provide noise isolation but can be uncomfortable and impair audio quality due to heat and moisture issues.
Innovation Solution
A headphone design with an open end and a dominant acoustical opening, featuring a feed-forward microphone positioned near the opening to enhance active noise cancellation by delaying sound entry and using a sound delaying unit to ensure invariant sound transmission, thereby improving noise isolation without compromising comfort or audio quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the headphone is made acoustically sealed, then passive noise dampening capability is improved, but comfort and audio quality deteriorate due to heat, moisture, and acoustical occlusion
Solution Approach 1:
The invention segments the acoustic system into sealed and open portions, with the earpad providing acoustic sealing while the acoustic opening remains open for ventilation. This allows simultaneous achievement of noise dampening through the sealed earpad and comfort through the open acoustic path for heat and moisture evacuation.
Solution Approach 2:
Different parts of the headphone have different acoustic properties: the earpad is acoustically sealed to provide noise isolation, while the acoustic opening remains open to provide ventilation and comfort. This local differentiation of acoustic quality resolves the contradiction between noise dampening and comfort.
2Ease of operation
If the headphone is made acoustically not sealed, then comfort and audio quality are improved, but passive noise dampening capability deteriorates
Solution Approach 1:
The invention uses a microphone to detect ambient noise and an active noise compensation unit to generate anti-noise signals that are fed back through the electro-acoustic transducer. This active feedback mechanism compensates for the lack of passive noise dampening in the open acoustic design, restoring noise isolation capability while maintaining comfort.
3Object-affected harmful factors
If a feed-forward microphone is positioned near the acoustic opening, then active noise cancellation is enhanced, but device complexity increases
Solution Approach 1:
The invention replaces complex mechanical positioning systems with a simplified approach: the microphone is positioned near the acoustic opening where it can effectively detect ambient noise. This strategic positioning, combined with electronic signal processing, achieves enhanced active noise cancellation without requiring complex mechanical adjustment mechanisms.
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
The design achieves significant active noise cancellation, restoring passive noise dampening capabilities while maintaining the comfort and audio quality benefits of open or vented headphones, with a feed-forward active noise cancellation system that effectively cancels ambient noise across a wide frequency range.
Implementation Method 1
a microphone adjacent or in the vicinity of the acoustical opening for detecting noise
Implementation Method 2
an electro-acoustical transducer inside the housing for reproducing an electrical signal into an audio signal
Implementation Method 3
Between the at least one acoustical opening and the first end of the housing, a sound delaying unit may be provided for delaying the sound which is entering the acoustical opening
Data Source
AI summary
A headphone is provided which comprises a housing with an open end and at least one defined dominant acoustic opening, an acoustically sealing earpad arranged at the open end of the housing, and at least one microphone arranged adjacent to common ear or in the vicinity of the dominant acoustical opening for detecting noise, wherein the dominant acoustic opening is arranged within a radius of 2 cm around a midpoint of the at least one microphone. The headphone or earphone also comprises an active noise compensation unit for performing an active noise compensation based on the output of the microphone and for generating a compensation signal. The headphone or earphone also comprises an electro-acoustical transducer inside the housing for reproducing the compensation signal.