Open-Ear Speaker Inverse Filtering for Elevation Perception
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Solution Overview
Problem
Conventional sound propagation correction techniques for stereophonic sound reproduction are not applicable to wearable open-ear speakers, as they are designed for ear canal-blocking types, and there is a need to improve elevation angle perception accuracy.
Innovation Solution
A sound propagation characteristics correction apparatus that includes a pseudo inverse filter generation unit and an acoustic signal correction unit to correct sound propagation characteristics for wearable open-ear speakers, using methods like kernel ridge regression and mollifiers to generate pseudo inverse filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inverse filter techniques are used for ear canal-blocking headphones, then elevation angle perception accuracy is improved, but the method is not applicable to open-ear speakers and requires microphone insertion into the auricle
Solution Approach 1:
The invention extracts the microphone insertion requirement from the system by using pre-measured transfer functions stored in memory. Instead of requiring real-time microphone insertion into the auricle, the system uses externally measured sound propagation characteristics that have been previously captured and stored, thereby eliminating the invasive measurement step while maintaining elevation angle perception accuracy.
Solution Approach 2:
The invention performs sound propagation characteristic measurements in advance and stores the transfer functions in memory before actual use. This preliminary action allows the system to have correction data ready without requiring microphone insertion during operation, making the system applicable to open-ear speakers while maintaining accurate elevation angle perception.
2Reliability
If microphone insertion into the auricle is performed for adaptive filter correction, then sound propagation characteristics are accurately corrected, but user burden increases and convenience decreases
Solution Approach 1:
The invention removes the burden of microphone insertion from the user experience by using pre-measured transfer functions. The system achieves reliable sound propagation characteristics correction through externally measured data that has been stored in memory, eliminating the need for users to undergo invasive microphone insertion procedures.
Solution Approach 2:
The invention uses copied transfer function data from external measurements stored in memory instead of performing real-time measurements with inserted microphones. This copying approach maintains correction accuracy while significantly reducing user burden and improving convenience.
3Device complexity
If conventional correction methods are applied to open-ear speakers, then the system design is simplified, but elevation angle perception accuracy deteriorates
Solution Approach 1:
The invention applies local quality by using speaker-specific transfer functions that are tailored to each open-ear speaker's unique sound propagation characteristics. Instead of using a generic correction method, the system stores and applies customized transfer functions measured for each specific speaker model, thereby achieving accurate elevation angle perception while maintaining simple system design.
Solution Approach 2:
The invention changes the parameter approach by using pre-measured transfer functions with specific frequency response characteristics tailored to open-ear speakers. This allows the system to achieve accurate elevation angle perception without requiring complex real-time measurement and adaptation mechanisms.
Data Source
AI summary
A sound propagation characteristics correction apparatus includes: a pseudo inverse filter generation unit that generates a pseudo inverse filter by a function that smooths sound propagation characteristics from a speaker driver of a wearable open-ear speaker to an ear canal entrance; and an acoustic signal correction unit that corrects an acoustic signal on the basis of the pseudo inverse filter and transmits the corrected acoustic signal to the wearable open-ear speaker.