Principle and technical application of dual microphone system for hearing aids

The dual microphone system for hearing aids is a relatively advanced acoustic technology, which aims to improve speech clarity and listening comfort in noisy environments, so as to solve the higher signal-to-noise ratio requirements of hearing-impaired patients than those with normal hearing.

Dual microphone principle

• 1. The dual microphone system consists of two independent omnidirectional microphones (microphones), usually one is a front microphone and the other is a rear microphone, which are located at different positions of the hearing aid (such as the front and back sides).
• 2. The system may also include an electronic delay (or signal delay circuit) to delay the sound signal from the rear microphone.

How Dual-Microphone Hearing Aids Work

• 1. Sound reception: The front and rear microphones receive sound signals from different directions respectively.
• 2. Signal processing: The two signals are transmitted to the microcomputer or digital signal processor (DSP) in the hearing aid movement. The MCU or DSP determines the direction of the sound source based on the time difference and intensity difference of the sound signal reaching the two microphones.
• 3. Directionality enhancement: Through algorithm processing, the system can enhance the sound signal from a specific direction (such as the front) while suppressing the noise signal from other directions (such as the back or side). This is usually achieved by adjusting the phase and gain control of the signals received by the two microphones.
• 4. Output amplification: The processed sound signal is amplified and output to the receiver (speaker) for the user to listen to.

Features and advantages of dual-microphone hearing aids

• 1. Directionality recognition: Only a dual-microphone system can realize directional functions, such as recognizing speech directional reception.
• 2. Noise suppression: By reducing the interference of environmental noise and improving the signal-to-noise ratio (SNR), the speech sound is clearer and more discernible.
• 3. Adaptive adjustment: Some advanced dual-microphone systems also have adaptive functions, which can automatically adjust the directional sensitivity and noise reduction effect according to changes in the surrounding environment.

Application scenarios

The dual microphone system of hearing aids is widely used in various occasions where speech clarity needs to be improved, especially in noisy environments:

• 1. Daily communication: When communicating one-to-one or with multiple people in noisy environments such as restaurants, supermarkets, and cafes, the dual microphone system can effectively reduce the interference of background noise and improve speech clarity.
• 2. Meeting occasions: In conference rooms, lectures, speeches and other occasions, the dual microphone system can help users better capture the voice of the speaker while suppressing other irrelevant noise.
• 3. Outdoor activities: In outdoor environments such as parks, streets, and transportation, the dual microphone system can also play an excellent noise reduction effect and improve the user's listening experience.

In summary, the dual microphone system of hearing aids provides users with a clearer and more comfortable listening experience in noisy environments through its unique principles and technical characteristics. With the continuous advancement and innovation of technology, the dual microphone system will play an increasingly important role in the field of hearing aids.