Earphone Microphone Dual-Receiver Signal Processing
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Solution Overview
Problem
Earphone microphones struggle to transmit speech sounds with sufficient frequency components above 3 kHz, essential for discriminating consonants, due to attenuation by the skull, leading to poor conversation quality.
Innovation Solution
An earphone microphone design with a unified L-shaped main unit and insert portion, featuring a first receiver inside the auditory canal and two external receivers positioned perpendicularly, along with a signal processor that includes a subtracter, high-pass filter, and adder to compensate for lost frequency components by adding external sound signals, thereby enhancing the transmitted sound signal with frequency components above 3 kHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a miniature microphone is embedded in an earpiece inserted into the external auditory canal to block surrounding noise, then noise isolation is improved, but frequency components above 3 kHz are attenuated during skull transmission
Solution Approach 1:
The invention divides the sound transmission path into two separate channels: an internal channel through the skull (capturing low-frequency vocal cord sounds) and an external channel through air (capturing high-frequency components). This segmentation allows each channel to be optimized for its frequency range, with the external microphone specifically capturing the high-frequency components lost through skull transmission.
Solution Approach 2:
The invention introduces an external microphone as an intermediary device positioned near the user's mouth to capture the sound source directly before it undergoes skull transmission. This intermediary captures the complete frequency spectrum, particularly the high-frequency components above 3 kHz, which are then combined with the internally captured low-frequency sounds to reconstruct the full speech signal.
2Object-affected harmful factors
If the earpiece is inserted deeply into the external auditory canal to improve noise isolation, then noise blocking is improved, but conversation smoothness deteriorates due to frequency loss
Solution Approach 1:
The invention merges the output signals from two separate microphones: the internal microphone capturing sounds through skull transmission and the external microphone capturing sounds through air transmission. By combining these two signal sources, the system reconstructs a complete frequency spectrum that maintains both noise isolation benefits and conversation smoothness, eliminating the frequency gaps that would otherwise degrade speech quality.
Solution Approach 2:
The invention changes the transmission parameter by introducing an alternative transmission path for high-frequency components. Instead of relying solely on skull transmission (which attenuates frequencies above 3 kHz), the system uses air transmission via the external microphone to preserve these high-frequency components, thereby maintaining speech intelligibility and conversation smoothness while keeping the earpiece deeply inserted for noise isolation.
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 design ensures a smooth conversation by compensating for lost frequency components, improving the transmission of consonant and vowel sounds, thus enhancing communication clarity over phones.
Implementation Method 1
miniature microphones receive sounds transmitted inside external auditory canals via skulls
Implementation Method 2
an external sound, which is emitted from a user's mouth so as to reach the second receiver via an external space
Implementation Method 3
The high-pass filter attenuates a low frequency component in the difference signal output from the subtracter
Data Source
AI summary
An earphone microphone is constituted of a main unit and an insert portion which are united in an L-shape. Two receivers are attached to the external surface of the main unit and exposed externally of a user's ear, while one receiver is attached to a distal end of the insert portion that is inserted into a user's external auditory canal and disposed opposite to a user's eardrum. A signal processor produces a difference signal between the output signals of two receivers exposed externally of the user's ear. The difference signal is subjected to high-pass filtering and subsequently added to the output signal of the receiver disposed inside the user's external auditory canal, thus producing a sound signal representing a user's sound. The sound signal includes a sufficient number of frequency components (e.g. frequency components higher than 3 kHz) prerequisite for discriminating the user's sound.