ANC Headset Venting for Leak-Tolerant Noise Cancellation
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Solution Overview
Problem
Active noise-cancelling audio headphones suffer from performance degradation due to leaks in the front cavity, particularly when users wear glasses or the earpieces are not correctly positioned, leading to controller instability and undesirable sounds.
Innovation Solution
Incorporating vents with specific dimensions and configurations to create intentional low-frequency leaks, ensuring the headphones maintain uniform performance by limiting phase shifts and sound leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the front cavity is made substantially airtight to block external noise, then noise isolation is improved, but any leaks cause performance degradation and controller instability
Solution Approach 1:
The patent applies preliminary action by intentionally creating controlled leaks before actual leaks occur. The first and second vents are pre-configured with specific dimensions and acoustic impedances to compensate for potential leaks, ensuring the transfer function remains stable even when the front cavity is not perfectly sealed.
Solution Approach 2:
The patent changes acoustic parameters by adjusting the acoustic impedance of the vents. The first vent has a first acoustic impedance and the second vent has a second acoustic impedance, where their combined effect compensates for leaks. This parameter adjustment maintains the transfer function stability despite leaks in the front cavity.
2Reliability
If vents are added to compensate for leaks, then transfer function stability is improved, but device complexity increases
Solution Approach 1:
The vents serve multiple functions: they provide acoustic compensation for leaks, maintain transfer function stability, and can be integrated into existing earpiece structures. The same vent structure that manages acoustic pressure also compensates for leaks, reducing the need for separate compensation mechanisms.
Solution Approach 2:
The patent applies local quality by positioning vents at specific locations within the earpiece structure. The first vent is configured with specific acoustic impedance characteristics and the second vent with different characteristics, allowing each vent to address specific aspects of leak compensation at localized positions within the front cavity.
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 solution effectively reduces phase shifts and maintains consistent noise cancellation performance even with leaks, preventing controller instability and undesirable sounds.
Implementation Method 1
said shell has at least one vent or a portion of low rear acoustic impedance made in said shell so as to make said shell acoustically transparent at low frequencies
Data Source
AI summary
The invention relates to an active noise-cancelling audio headphones having two circum-aural earpieces, comprising a partition designed to face an ear; said partition incorporating at least one vent passing through said partition so as to generate intentional leaks having a length greater than 1.5 mm and a width selected in such a way that there are eithera ratio between said length and said width is less than or equal to 8:1 if a median section is greater than 1.7 mm2; ora ratio between said length and said width is less than or equal to 4:1 if said median section is less than 1.7 mm2.