Headphone Vent Passage for Low-Frequency Tuning
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Solution Overview
Problem
Existing headphones face challenges in adjusting low-frequency sound characteristics due to limited sealability and air pressure issues, which affect wearing comfort and productivity.
Innovation Solution
A headphone design featuring a vent passage system with adjustable through holes in the baffle and passage forming members allows for easy release of air pressure from the front cavity to the external space, enabling fine-tuning of low-frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the front cavity is completely sealed to enhance low frequency sound level, then low frequency sound is prevented from leaking, but diaphragm vibration is strongly damped by back pressure
Solution Approach 1:
The patent applies a porous acoustic absorber material within the front cavity to create controlled acoustic damping. This porous structure allows air to pass through while providing acoustic resistance, enabling the cavity to maintain sealability for low frequency sound reinforcement while preventing excessive back pressure buildup that would dampen diaphragm vibration. The porous material acts as an acoustic impedance element that manages air pressure dynamics.
2Manufacturing precision
If the front cavity is completely sealed to secure low frequency level, then low frequency sound is maintained, but wearing comfort deteriorates due to air pressure buildup
Solution Approach 1:
The porous acoustic absorber material provides pressure equalization by allowing slow air flow through its porous structure. This maintains the sealed appearance and acoustic integrity of the front cavity while enabling pressure relief to external space, preventing discomfort from pressure buildup during wearing.
Solution Approach 2:
The porous acoustic absorber acts as an intermediary between the sealed front cavity and the external environment. It mediates the conflict between maintaining sealability for acoustic performance and allowing pressure equalization for comfort, providing a controlled transition path for air molecules.
3Reliability
If a pressure equalizer port is inserted through housing with adhesive to equalize air pressure, then low frequency characteristics are maintained, but productivity decreases and adjustment flexibility is limited
Solution Approach 1:
The patent merges the pressure equalization function with the existing acoustic absorber material that is already placed in the front cavity for acoustic management. By combining these two functions into a single component, the design eliminates the need for separate pressure equalizer ports requiring adhesive assembly, thereby improving productivity while maintaining reliable pressure equalization.
Solution Approach 2:
The acoustic absorber material is designed to serve multiple functions simultaneously: acoustic damping, pressure equalization, and structural filling. This multi-functionality eliminates the need for dedicated pressure equalization components, simplifying assembly and improving productivity while maintaining all necessary functions.
4Reliability
If the pressure equalizer port is fixed on housing to equalize air pressure, then air pressure is balanced, but fine adjustment of low frequency characteristics becomes difficult
Solution Approach 1:
The patent enables parameter adjustment by varying the physical properties of the porous acoustic absorber material, such as porosity, density, thickness, or flow resistance. These parameter changes allow fine-tuning of both pressure equalization performance and low frequency acoustic characteristics, providing adaptability without compromising pressure balance functionality.
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 low-frequency sound quality and adjustability while improving wearing comfort and productivity by allowing for precise control of air pressure and sound resonance.
Implementation Method 1
The front cavity communicates with an external space through the pressure equalizer port. The pressure equalizer port is formed to have a predetermined length and an effective cross-sectional area in accordance with the desired characteristics of the headphone. As a result, in the headphone disclosed in Published Japanese Translation of PCT Application No. 2017-513356, decrease in level of the low frequency range is suppressed, and the air pressure in the front cavity is equalized with the pressure of the external space.
Implementation Method 2
a driver unit that generates sound waves based on an electrical signal
Implementation Method 3
a passage forming member that is attached to the baffle member and forms a vent passage with the baffle member
Data Source
AI summary
A headphone in which the air pressure in a front cavity can be released to an external space, and whose characteristics in a low frequency range can be simply and finely adjusted is provided. The headphone includes: a driver unit; a baffle member holding the driver unit; the passage forming member attached to the baffle member and forming a vent passage with the baffle member; an ear pad defining a first space; and a cover member defining a second space. The baffle member includes: a first surface facing the first space; a second surface facing the second space; and a first through hole communicating with an internal space of the vent passage. The passage forming member includes a second through hole communicating with the internal space of the vent passage. The second space communicates with an external space of the cover member. The first space communicates with the second space through the first through hole, the vent passage, and the second through hole.