Headrest Loudspeaker Gain Control for Private Vehicle Alerts
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Solution Overview
Problem
Existing sound systems in vehicles struggle to output notifications to a specific user without disturbing others, as high volumes can bother other passengers, while reducing volume makes it difficult for the intended user to hear the sound.
Innovation Solution
A sound system with a loudspeaker positioned closest to the intended user, a gain adjuster, and a processor that calculates the optimal gain based on noise levels and pre-set transfer functions to ensure the notification sound is louder for the user and masked by noise for others, using a microphone to estimate noise levels and adjust the gain accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the volume of the loudspeaker is increased to make the notification sound easier for the user to hear, then the sound becomes audible to the user, but other users in the vehicle can also hear it which causes disturbance
Solution Approach 1:
The system applies different sound levels to different spatial locations by positioning the loudspeaker on the headrest closest to the target user and using transfer functions to calculate position-specific gain adjustments. This creates localized sound zones where the notification is audible to the intended user while remaining inaudible to other users in different seats.
Solution Approach 2:
The system pre-calculates transfer functions between the loudspeaker and multiple user positions before actual notification delivery. These transfer functions are stored and used to determine the optimal gain setting in advance, allowing the system to quickly adjust to different user configurations without real-time computation delays.
2Object-affected harmful factors
If the volume of the loudspeaker is reduced to avoid disturbing other users, then other users cannot hear the sound, but the notification sound becomes difficult for the intended user to hear as well
Solution Approach 1:
The system creates a localized sound field by positioning the loudspeaker on the headrest and using transfer function-based gain adjustment. This allows the notification sound to be sufficiently loud for the intended user while being inaudible to other users, effectively solving the contradiction between audibility and non-disturbance through spatially differentiated sound quality.
3Ease of operation
If a fixed gain is used for the notification sound, then the system is simple to operate, but it cannot adapt to different noise levels and user positions
Solution Approach 1:
The system automatically determines the optimal gain setting by utilizing pre-stored transfer functions and real-time noise level measurements from the microphone. The processor automatically selects and applies the appropriate gain value based on the current user position and ambient noise conditions, eliminating the need for manual user adjustment while maintaining simplicity of operation.
Solution Approach 2:
The system incorporates a microphone that continuously monitors the ambient noise level in the vehicle and feeds this information back to the processor. The processor uses this feedback along with the transfer functions to dynamically adjust the gain setting, enabling the system to adapt to changing noise conditions and user positions while maintaining optimal notification sound levels.
Data Source
AI summary
A “sound system” is provided for outputting a notification sound easy for a specific user to hear within a range in which other users are not bothered. A notification sound output from a notification sound source is output to a driver via a loudspeaker situated on headrest of the driver's seat after gain adjustment by a variable gain amplifier. Gain setter estimates power of noise at each seat based on noise collected by microphone, calculates gain for notification sound that makes notification sound larger than noise at the driver's seat and makes notification sound smaller than noise at a specific seat by using a first transfer function of notification sound from loudspeaker to the user on the driver's seat and a second transfer function of notification sound from loudspeaker to the user on the specific seat, which are previously determined, and sets the gain in the variable gain amplifier.