Headrest Speaker Enclosure Opening for Low-Frequency Leakage Control
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Solution Overview
Problem
Existing speaker devices in vehicle seats suffer from low frequency sound leakage to the surroundings and adjacent seats, making individual source reproduction challenging and requiring expensive crosstalk cancellation systems.
Innovation Solution
An acoustic apparatus with at least two speakers, each directed towards a listener's ear, and an enclosure with an opening larger than the speaker's effective vibration area positioned further forward, utilizing opposite phase sound pressure to cancel low frequency sound leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a speaker device uses Helmholtz resonance to enhance low frequency sound output, then low frequency sound pressure is improved, but sound leakage to the surroundings worsens
Solution Approach 1:
The patent applies preliminary anti-action by positioning an opening in the enclosure at a location further from the ear than the speaker, and sizing the opening area to be greater than or equal to the effective vibration area of the speaker. This configuration creates sound pressure cancellation through the opening that counteracts the low frequency sound pressure generated by the speaker before it can leak to the surroundings, thereby preventing harmful sound leakage while maintaining the desired low frequency output to the listener.
2Object-generated harmful factors
If a small opening is used in the speaker box to cancel sound, then some sound leakage is reduced, but low frequency sound cancellation is insufficient
Solution Approach 1:
The patent applies parameter changes by specifying that the opening area must be greater than or equal to the effective vibration area of the speaker, and the opening must be positioned at a specific location further from the ear than the speaker. These parameter specifications ensure that the opening can effectively cancel low frequency sound pressure through proper acoustic impedance matching and phase cancellation, making the sound leakage prevention reliable and effective for low frequency ranges.
3Measurement precision
If speakers are positioned close to the user's ears for individual source reproduction, then individual seat audio quality is improved, but sound leakage to adjacent seats worsens
Solution Approach 1:
The patent applies preliminary anti-action by creating sound pressure cancellation through the opening in the enclosure, which counteracts the low frequency sound pressure generated by the speaker before it can propagate to adjacent seats. This allows speakers to be positioned close to the user's ears for high-quality individual source reproduction while the cancellation effect prevents crosstalk and sound leakage to neighboring seats.
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
Effectively prevents sound leakage to the surroundings and adjacent seats, ensuring clear middle and high frequency sound reception while maintaining listener safety and reducing sound leakage.
Implementation Method 1
the sound output to the front of the speaker box and the sound output from the side wall opening cancel each other, thereby preventing a portion of the sound generated from the headrest from being transmitted to the side or rear
Implementation Method 2
at each passage and outlet, the Helmholtz resonator principle can be implemented to produce sound at a higher volume at a frequency lower than the cutoff frequency of the speaker
Data Source
AI summary
An acoustic apparatus includes at least two speakers, each of the speakers having a sound producing direction directed to a corresponding ear of left and right ears of a listener; and an enclosure covering a back portion of a corresponding speaker of the speakers. An opening to open the enclosure is provided at a position further away from the corresponding ear than the corresponding speaker of the speakers. An opening area of the opening is greater than or equal to an effective vibration area of each of the speakers.