Earpiece Helmholtz Resonator for 7.5 kHz Resonance Control
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Solution Overview
Problem
In-ear headphones suffer from sound quality degradation due to ear canal resonance, particularly a resonance peak around 7.5 kHz, which affects the frequency response and comfort for users.
Innovation Solution
The design incorporates a sound guide element and a volume element forming a Helmholtz resonator, which is tuned to absorb resonance frequencies, with adjustable dimensions and a damping element to customize acoustic properties for individual ear canal geometries, reducing resonance peaks and enhancing sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ear canal is sealed with the in-ear receiver, then sound isolation is improved, but resonance amplification occurs around 7.5 kHz degrading sound quality
Solution Approach 1:
The patent introduces a Helmholtz resonator that exploits resonance physics to counteract the harmful ear canal resonance. The resonator is tuned to the same frequency as the ear canal resonance (around 7.5 kHz) but produces an opposing acoustic signal that cancels out the unwanted resonance peak, converting the harmful resonance effect into a beneficial cancellation mechanism
Solution Approach 2:
The Helmholtz resonator is designed to produce an anti-phase acoustic signal before the resonance amplification fully develops. By tuning the resonator's neck dimensions and volume to match the ear canal's resonant frequency, the system preemptively generates a counteracting sound wave that neutralizes the resonance peak before it degrades sound quality
2Adaptability or versatility
If the second opening of the volume element connects to the ear canal, then acoustic resonance control is improved, but the opening should not directly connect to the sound-guiding element to maintain acoustic integrity
Solution Approach 1:
The patent positions the first opening of the sound-guiding element and the second opening of the volume element at different locations on the housing. This spatial separation ensures that the volume element can connect to the ear canal for resonance control while the sound-guiding element maintains its acoustic integrity by not having its opening blocked or interfered with by the volume opening
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 solution effectively reduces resonance peaks in the 7.5 kHz range, improving sound quality and comfort by adapting to the specific geometry of each user's ear canal, thereby enhancing the overall listening experience.
Implementation Method 1
A Helmholtz resonator is formed by the acoustic mass of the opening and the volume of the volume element. This Helmholtz resonator can be tuned to reduce the resonance peak caused by a resonant frequency of the ear canal.
Implementation Method 2
The ear canal, sealed with the in-ear receiver, exhibits resonance when excited at a specific resonant frequency. The resonant frequency in question might, for example, be around 7.5 kHz.
Implementation Method 3
The sound guide element directs the sound from the acoustic transducer to the interface between the (in-the-ear) receiver and the user's ear canal.
Data Source
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AI summary
There is provided an earpiece having a first side towards the ear, an acoustic transducer for outputting a sound signal and a sound guide element having a first end and a second end. In that case the first end faces the acoustic transducer and the second end faces the first end of the (ear canal) earpiece. The sound guide element serves for guiding the sound signal to an ear canal of a user. The sound guide element has a first opening at its second end. The (ear canal) earpiece also has at least one volume element which delimits a volume and which has at least one second opening for connecting the volume to the first end of the ear canal earpiece.