Bone Conduction Transducer Calibration for Loudness-Matched Spatial Audio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio systems in artificial reality headsets face challenges in delivering high-quality, spatial audio through bone conduction without occluding the ear canals, requiring effective calibration of bone conduction transducer assemblies to match the loudness perception of air conduction systems.
Innovation Solution
A method involving presenting tones of different frequencies through both air and bone conduction transducers, adjusting the bone conduction tones to match loudness levels, recording ear-canal sound pressures and voltages, and generating an equalization filter to calibrate the bone conduction transducer assembly for accurate audio delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bone conduction transducer assembly is used to deliver audio content, then ear canals remain un-occluded allowing environmental acoustic signals to be received, but the loudness perception does not match that of air conduction system
Solution Approach 1:
The patent applies parameter changes by measuring the actual loudness perception of the bone conduction transducer assembly across different frequencies and comparing it to the air conduction system. An equalization filter is then generated with adjusted frequency parameters to match the loudness perception between the two transducer types, resolving the contradiction between maintaining open ear canals and achieving accurate loudness perception.
2Manufacturing precision
If calibration of bone conduction transducer assembly is performed to match loudness perception, then audio quality is improved, but additional measurement and processing steps are required
Solution Approach 1:
The patent implements feedback by measuring the actual loudness perception of the bone conduction transducer assembly and using this measurement information to generate an equalization filter. The filter is then applied to adjust the audio output, creating a closed-loop calibration process that improves audio quality while systematically managing the complexity through automated measurement and processing.
3Reliability
If equalization filter is generated based on ECSP and voltage measurements, then spatial audio realism is enhanced, but measurement and computation time increases
Solution Approach 1:
The patent applies preliminary action by performing the calibration process during the initial setup phase before the user begins using the headset for normal activities. The ECSP and voltage measurements are taken, and the equalization filter is generated in advance, so that the enhanced spatial audio realism is available immediately without adding time loss during actual use.
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
This approach ensures that the bone conduction transducer assembly provides audio that matches the loudness perception of the air conduction system, enhancing the quality and realism of spatial audio in artificial reality headsets.
Implementation Method 1
A first tone of a plurality of tones that are at different frequencies is presented to the wearer via an air conduction transducer assembly
Implementation Method 2
A corresponding tone having a same frequency as the first tone is then presented to the wearer via a bone conduction transducer assembly of the headset
Data Source
AI summary
Calibration of a headset that uses bone conduction to provide audio content to a wearer is presented. A first tone of a plurality of tones that are at different frequencies is presented to the wearer via an air conduction transducer. A corresponding tone having a same frequency as the first tone is also presented to the wearer via a bone conduction (BC) transducer. The corresponding tone is adjusted such that a level of loudness is within a threshold range of a level of loudness of the first tone. An ear-canal sound pressure (ECSP) resulting from the first tone is recorded and a voltage applied to the BC transducer for generating the adjusted corresponding tone. An equalization filter is generated based in part on the ECSP and the voltage, the equalization filter for filtering an audio signal for presentation via the BC transducer.