Four-transducer Acoustic Device for Sound Leakage Control
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Solution Overview
Problem
Conventional headphones occlude outside sound, affecting conversation and environmental awareness, but when designed to allow outside sounds in, they often make internal sounds audible to others, lacking effective sound isolation.
Innovation Solution
A body-worn acoustic device with four transducers, two closer to each ear for direct sound delivery and two farther away for far-field cancellation, allowing independent control of phase and frequency response to optimize sound pressure levels and minimize radiated power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If headphones are located on or in the ears, then sound pressure level at the ear is improved, but outside sound occlusion increases
Solution Approach 1:
The system divides the audio output into multiple transducers positioned at different locations: some transducers are placed close to the ear for direct sound delivery, while others are positioned farther away for far-field cancellation. This segmentation allows simultaneous achievement of high SPL at the ear and reduction of outside sound leakage.
Solution Approach 2:
The system applies preliminary anti-action by using far-field transducers to generate anti-phase sound waves that cancel out the sound radiated by near-field transducers in the far-field region. This preemptive cancellation prevents sound leakage before it can be heard by others, while still delivering adequate sound to the user's ear.
2Object-affected harmful factors
If headphones are designed to sit off the ears, then outside sound occlusion is reduced, but sound produced by headphones becomes audible to others
Solution Approach 1:
The system applies local quality by assigning different functions to transducers based on their spatial location. Near-field transducers are optimized for sound delivery to the ear, while far-field transducers are optimized for sound cancellation in the external environment. Each transducer group has tailored phase and frequency response characteristics appropriate to its local function.
Solution Approach 2:
The system converts the potentially harmful effect of sound radiation into a beneficial cancellation effect. By deliberately radiating sound through far-field transducers in anti-phase, the system creates destructive interference that cancels out sound leakage, transforming what would be harmful sound propagation into a useful noise-cancellation mechanism.
3Stress or pressure
If multiple transducers are used with independent phase and frequency control, then sound pressure level and sound cancellation are improved, but device complexity increases
Solution Approach 1:
The system implements dynamics by enabling independent and variable control of phase and frequency response for each transducer group. The controller can dynamically adjust the phase relationship between near-field and far-field transducers, as well as apply frequency-dependent filtering, to optimize performance across different operating conditions and frequency ranges.
Solution Approach 2:
The system applies parameter changes by varying the phase shift and frequency response characteristics of different transducer groups. By changing these parameters dynamically, the system optimizes the balance between sound delivery to the ear and far-field sound cancellation, achieving high SPL at the ear while minimizing sound leakage to others.
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
Enables effective listening to external sounds while minimizing sound leakage to others, providing versatile modes for varying sound pressure levels and environmental noise conditions, enhancing user awareness and privacy.
Implementation Method 1
The first acoustic transducer is adapted to radiate sound along a first sound axis
Implementation Method 2
the second acoustic transducer is adapted to radiate sound along a second sound axis, where the first sound axis is pointed toward the location of the first ear and the second sound axis is pointed away from the location of the first ear
Data Source
Figure 1~2
Figure 3~4
Figure 5A
AI summary
An acoustic device that is adapted to be worn on the body of a user, with a first acoustic transducer and a second acoustic transducer, where the first transducer is closer to the expected location of a first ear of the user than is the second transducer, a third acoustic transducer and a fourth acoustic transducer, where the third transducer is closer to the expected location of a second ear of the user than is the fourth transducer, and a controller that is adapted to independently control the phase and frequency response of the first, second, third and fourth transducers.