Signal Processing Circuit for Headphone-Loudspeaker Audio Localization
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Solution Overview
Problem
Headphones often fail to accurately localize sound, leading to 'inside-the-head' and 'front-back confusion' effects, which are undesirable, especially when audio is synchronized with video content, as they cannot effectively replicate the externalization of sound sources.
Innovation Solution
A signal processing circuit that simultaneously provides audio to both headphones and a loudspeaker, using delay lines and filters to coordinate audio signals and adapt gain and equalization based on microphone feedback, ensuring that high frequencies are directed to the loudspeaker and low frequencies to the headphones, thereby enhancing sound localization and creating an 'out-of-head' audio experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If audio is provided only through headphones, then portability and personal audio experience are improved, but sound localization accuracy deteriorates causing inside-the-head effect
Solution Approach 1:
The patent combines headphone and loudspeaker systems into a hybrid audio output configuration. The signal processing circuit simultaneously drives both headphones and loudspeakers, merging the portability benefits of headphones with the externalization benefits of loudspeakers to resolve the localization accuracy issue.
Solution Approach 2:
The audio signal is segmented into different frequency components and routed differently: high frequencies are directed to the loudspeaker for externalization cues, while low frequencies are directed to the headphones for bass reproduction. This segmentation allows each device to contribute its strengths to the overall sound localization experience.
2Measurement precision
If high frequencies are directed to loudspeaker and low frequencies to headphones, then sound localization is improved, but signal processing complexity increases
Solution Approach 1:
Different frequency bands are assigned to different output devices based on their acoustic characteristics. The signal processing circuit applies local quality by directing high frequencies (which provide localization cues) to the loudspeaker and low frequencies to the headphones, optimizing each device's contribution to the overall audio experience.
3Reliability
If delay lines are used to coordinate audio signals, then sound synchronization is improved, but device complexity increases
Solution Approach 1:
The signal processing circuit applies preliminary action by pre-calculating and applying appropriate time delays to the audio signals before they reach the headphones and loudspeakers. This ensures that sound waves from both devices arrive at the listener's ear simultaneously, achieving synchronization without requiring complex real-time adjustment mechanisms.
Data Source
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AI summary
A signal processing circuit (300) comprising: a first signal processor (316) configured to produce a first output signal (318) suitable for driving a first headphone speaker (302); a second signal processor (336) configured to produce a second output signal (338) suitable for driving a second headphone speaker (304); a third signal processor (320) configured to receive the first input signal (312) and/or the second input signal (332) and to produce a third output signal (322) suitable for driving a first loudspeaker (306); and simultaneously provide the first output signal to the first headphone speaker, the second output signal to the second headphone speaker, and the third output signal to the first loudspeaker.