Hearing Aid Microphone Mixing for Spatial Sound Perception
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Behind-the-ear (BTE) hearing assistance devices lack directional filtering effects of the pinna, leading to impaired spatial sound perception and externalization of sound sources, as microphones are positioned above the ear, whereas custom in-the-canal devices with directional microphones face port spacing limitations and interference from pinna reflections.
Innovation Solution
A hearing assistance device with a combination of a first microphone outside the ear canal and a second microphone inside the ear canal, where hearing assistance electronics mix low frequency components from the first microphone with high frequency components from the second microphone to generate a modified signal that includes enhanced spatial characteristics, effectively replicating the pinna's filtering effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If BTE hearing assistance devices use microphones positioned above the pinna, then the device housing can accommodate multiple microphones, but the directional filtering effects of the pinna are lost
Solution Approach 1:
The patent divides the audio frequency spectrum into multiple bands and processes each band separately through different microphone inputs. Low frequency components are processed from the BTE microphone while high frequency components are processed from the CIC microphone, allowing each microphone type to contribute its strengths in appropriate frequency ranges.
Solution Approach 2:
The patent combines signals from two different microphone positions (BTE and CIC microphones) into a single processed output signal. This merging allows the system to capture both the omnidirectional low frequency information from the BTE microphone and the directionally-filtered high frequency information from the CIC microphone.
2Loss of information
If CIC devices use directional microphones, then spatial sound perception can be enhanced, but port spacing is insufficient and pinna reflections cause interference
Solution Approach 1:
The patent applies different processing strategies to different frequency bands rather than treating all frequencies uniformly. Low frequency components are processed with one approach while high frequency components are processed with another, allowing optimization for each frequency range's specific characteristics and challenges.
Solution Approach 2:
The patent uses the BTE microphone as an intermediary to capture low frequency sound information that is not affected by pinna reflections. This intermediary microphone provides a clean low frequency signal that complements the high frequency signal from the CIC microphone, which does capture pinna effects but suffers from reflection interference.
3Loss of information
If hearing assistance electronics mix low frequency components from outside ear with high frequency components from inside ear, then spatial characteristics are enhanced, but device complexity increases
Solution Approach 1:
The patent changes the frequency domain parameters of the input signals by applying frequency-dependent filtering and selective component extraction. The system transforms the mixed frequency spectrum into separated low and high frequency components that can be independently processed and then recombined with enhanced spatial characteristics.
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
Enhances spatial sound perception by providing directional cues and externalization of sound sources, allowing users to better locate sound sources in space, improving sound localization and reducing confusion about sound source direction.
Implementation Method 1
hearing assistance electronics adapted to mix low frequency components of acoustic sounds received using the first microphone with high frequency components of sound received using the second microphone
Implementation Method 2
The pinna of the user's ear, as well as other portions of the user's body, including the head and torso, provide filtering of sound received by the user
Data Source
AI summary
This document provides a hearing assistance device for playing processed sound inside a wearer's ear canal, the hearing assistance device comprising a first housing, signal processing electronics disposed at least partially within the first housing, a first microphone connected to the first housing, the first microphone adapted for reception of sound, a second microphone configured to receive sound from inside the wearer's ear canal when the hearing assistance device is worn and in use and microphone mixing electronics in communication with the signal processing electronics and in communication with the first microphone and the second microphone, the microphone mixing electronics adapted to combine low frequency information from the first microphone and high frequency information from the second microphone to produce a composite audio signal.