Dual-Speaker Earphone Acoustic Layout for Low-Frequency Distortion Control

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Solution Overview

Problem

Existing earphones using single-channel electrical signal driving for speakers in different frequency bands suffer from diaphragm distortion, particularly in high-frequency bands, leading to compromised sound quality.

Innovation Solution

The earphone design includes two speakers with distinct frequency bands, where the second speaker is driven by a driving circuit with a frequency not higher than 200 Hz, and features a communication hole with specific acoustic impedance and positioning to enhance sound output and reduce interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If single-channel electrical signal driving is adopted for speakers in different frequency bands, then the device complexity is reduced, but diaphragm distortion occurs leading to compromised sound quality

Engineering Contradiction:
Improvedriving circuit complexityVSAvoidsound quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The driving circuit is segmented into multiple independent channels, with each channel dedicated to driving a specific speaker responsible for a particular frequency band. This segmentation allows each speaker to receive appropriately filtered electrical signals, preventing diaphragm distortion while maintaining manageable circuit complexity through modular design

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If multi-channel electrical signal driving is adopted for speakers in different frequency bands, then sound quality is improved by preventing diaphragm distortion, but the device complexity increases

Engineering Contradiction:
Improvesound qualityVSAvoiddriving circuit complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The driving circuit is divided into multiple independent channels, each dedicated to a specific speaker and frequency band. This segmentation enables precise control of electrical signals for each speaker, preventing diaphragm distortion while managing complexity through modular architecture

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Electrical signal filters serve as intermediary components between the signal source and each speaker. These filters mediate the signal processing by selectively passing appropriate frequency bands to each speaker, enabling multi-channel driving without requiring complex direct control circuits

Inventive Principle:
Principle #24Intermediary (Mediator)

3Speed

If the diaphragm of a high-frequency speaker is made thin to reduce mass, then the speaker responds better to high frequencies, but the diaphragm experiences excessive amplitude when receiving low-frequency signals causing distortion

Engineering Contradiction:
Improvediaphragm response speedVSAvoidsound quality
Core Design Contradiction:
SpeedVSManufacturing precision

Solution Approach 1:

The electrical signal driving is segmented into frequency-specific channels, where each channel delivers only the appropriate frequency band to its designated speaker. This prevents thin high-frequency diaphragms from receiving low-frequency signals that would cause excessive amplitude and distortion

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The frequency parameters of the electrical signals are changed and adjusted for each speaker based on their specific frequency bands. By modifying the frequency parameters of the input signals, the system prevents thin diaphragms from experiencing excessive amplitude at frequencies they cannot handle, thereby maintaining sound quality

Inventive Principle:
Principle #35Parameter changes

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

The design improves sound quality by minimizing diaphragm distortion and optimizing sound wave propagation, resulting in enhanced auditory experience.

Implementation Method 1

an acoustic impedance at the communication hole is in a range of 5×10^8

Methodology Applied
Scientific EffectAcoustic impedance:

Implementation Method 2

The driving circuit is configured to drive the first speaker and the second speaker

Methodology Applied
Scientific EffectElectromagnetic conversion:

Implementation Method 3

The first speaker includes a first diaphragm. The first diaphragm and the core housing cooperate to form a first front cavity and a first rear cavity

Methodology Applied
Scientific EffectElectromagnetic vibration:

Data Source

PatentEP4708909A1earphone
Publication Date: 2026.03.11 SHENZHEN SHOKZ CO LTD
  • EP4708909A1 patent drawingFigure 1
  • EP4708909A1 patent drawingFigure 2
  • EP4708909A1 patent drawingFigure 3

AI summary

The present disclosure relates to an earphone, and specifically relates to the technical field of electronic devices. The first speaker includes a first diaphragm, the first diaphragm and a core housing cooperating to form a first front cavity and a first rear cavity located on two sides of the first diaphragm. The second speaker includes a second diaphragm and a speaker housing, the second diaphragm, the speaker housing, and the core housing cooperating to form a second front cavity and a second rear cavity located on two sides of the second diaphragm. The core housing is provided with a first sound outlet for guiding a sound from the first front cavity to outside of the core housing and a second sound outlet for guiding a sound from the second front cavity to the outside of the core housing. And the second speaker is further provided with a communication hole for communicating the second rear cavity with outside of the second speaker.