In-Ear Listening Device Preserving Spatial Cues via Transfer Function
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Solution Overview
Problem
Headphones and in-ear monitors that block the ear canal reduce directional cues from environmental sounds, leading to decreased situational awareness and user dissatisfaction.
Innovation Solution
A listening device with a reference microphone outside the blocked ear canal and a loudspeaker inside, along with internal microphones, adjusts internal sounds based on a computed transfer function to mitigate variations between environmental and internal sounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If headphones or in-ear-monitors block the ear canal to transmit sounds, then sound transmission quality is improved, but directional cues are reduced or lost
Solution Approach 1:
The patent introduces an intermediary processing system that captures environmental sounds through external microphones, processes them to preserve directional information, and transmits them through the in-ear monitor. This intermediary processing chain maintains spatial cues that would otherwise be lost due to ear canal blocking
Solution Approach 2:
The system uses feedback from microphones positioned to capture environmental sounds and incorporates this feedback into the audio transmission. By continuously monitoring and adjusting the audio signal based on environmental sound input, the system preserves directional cues while maintaining sound isolation
2Object-affected harmful factors
If the ear canal is blocked by listening devices, then noise isolation is improved, but situational awareness is reduced
Solution Approach 1:
The patent segments the audio processing into multiple independent components: external microphones capture environmental sounds, separate processing channels preserve directional information, and selective transmission delivers relevant audio information. This segmentation allows noise isolation while maintaining situational awareness through preserved spatial audio cues
Solution Approach 2:
The system dynamically adjusts audio parameters such as gain, frequency response, and spatial positioning based on environmental conditions. By changing these parameters in real-time, the system maintains noise isolation while adapting to preserve situational awareness when environmental sounds are relevant
3Measurement precision
If environmental sounds are transmitted through blocked ear canal, then sound quality varies due to bouncing off surfaces, but this creates unwanted bias in reproduced sounds
Solution Approach 1:
The patent extracts the problematic bouncing effect from the sound transmission path by using external microphones to capture environmental sounds before they enter the blocked ear canal. By taking out the sound capture point from inside the ear canal to the external environment, the system eliminates the unwanted bias caused by surface reflections while maintaining accurate sound reproduction
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 device effectively transmits adjusted environmental sounds with inherent spatial cues, enhancing situational awareness and user satisfaction during artificial reality experiences.
Implementation Method 1
a reference microphone positioned outside a blocked ear canal of a user wearing the listening device to receive the environmental sounds and generate first signals based in part on the environmental sounds
Implementation Method 2
A loudspeaker is coupled to the reference microphone and positioned inside the ear canal. The loudspeaker generates internal sounds based in part on the first signals
Implementation Method 3
An internal microphone is positioned inside the ear canal to receive the internal sounds from the loudspeaker and generate second signals based in part on the internal sounds
Implementation Method 4
The variation may be caused by the listening device blocking the ear canal and the internal sounds bouncing off the surfaces of the ear canal and the ear
Data Source
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AI summary
A listening device includes a reference microphone positioned outside a blocked ear canal of a user to receive environmental sounds and generate first signals based on the environmental sounds. A loudspeaker is coupled to the reference microphone and positioned inside the ear canal to generate internal sounds based on the first signals. An internal microphone is positioned inside the ear canal to receive the internal sounds from the loudspeaker and generate second signals based on the internal sounds. A controller is coupled to the internal microphone and the reference microphone to compute a transfer function based on the first signals and the second signals. The transfer function describes a variation between the environmental sounds and the internal sounds caused by the listening device blocking the ear canal. The controller adjusts, based on the transfer function, the internal sounds to mitigate the variation.