What are Sound Sensors? Structure and principle of operation

According to statistics, more than 90% of smartphones globally are equipped with sound sensors. This impressive number shows the undeniable importance of sound sensor technology in today’s modern life. So what are sound sensors and why are they becoming so popular in the lives around us? Let’s explore with RX Tradex in the article below.

1. What are sound sensors?

Sound sensors are a specialized device that recognizes the level of sound in the surrounding environment. These sensors have many practical applications in life such as signal switching, monitoring, and security. With its high accuracy and sensitivity, the sound sensor can be flexibly customized to suit specific needs, making it more convenient to use.

The sound sensor is capable of detecting sound levels with noise measured in decibels (DB), in the frequency range from 3kHz to 6kHz – equivalent to the frequency threshold that the human ear can hear.

2. Structure of sound sensor

Sound sensors vary depending on the type of sensor and the technology applied because they are quite complex in construction. Here is the basic structure of an electromagnetic sound sensor:

• Sensor diaphragm: This is the most important part, usually made from sound-sensitive materials such as polymers, metals, or ceramics. This sensor membrane vibrates when it encounters sound waves and converts them into mechanical motion.
• Electrode: The electrode is the part that comes into contact with the sensor membrane, which is made from conductive materials such as metals. When the sensor membrane vibrates due to the pressure of the sound, the electrode generates an electrical signal that corresponds to the frequency and intensity of the sound.
• Converters and signal processing: Electromagnetic  signals from the electrodes will be fed through electronic components such as amplifiers, filters, and analog-to-digital converters (ADCs). These components help to amplify the signal, eliminate interference, and convert the signal to digital form, making the process of analyzing and processing the signal easier.

3. Principle of operation

Sound sensors work on the principle of converting sound energy into electrical signals. Some of the ways in which electromagnetic sound sensors typically work:

• Sensor membrane: When sound waves act on the sound-sensitive sensor membrane, the membrane vibrates with the frequency and intensity of the sound. This mechanical movement is the first step in converting sound waves into electrical signals.
• Electrodes: The sensor membrane is integrated with one or more electrodes. When the film vibrates, the electrodes move with it, resulting in a change in the electric field around the electrodes.
• Voltage generation: This change in the electric field creates a potential or current, which corresponds to the oscillation of the initial sound wave. This is how the sensor converts sound into an electrical signal.
• Signal processing: The resulting electrical signal is fed into processing components such as amplifiers, filters, and analog-to-digital converters (ADCs). This process enhances the signal, eliminates interference, and converts the signal from analog to digital for easy processing and analysis.
• Applications and subsequent processing: Once processed, digital signals can be used for a variety of purposes such as voice recognition, recording, device control, or other audio-related applications.

Depending on the type of sensor, the principle of operation may vary. Common types of sensors include electromagnetic sensors, capacitive sensors, and piezoelectric sensors, each with its own advantages and ways of operating.

4. Some applications of sound sensors

Sound sensors are widely used in many fields thanks to its diverse capabilities. Some typical applications such as:

• Speech recognition system: sound sensors play an important role in voice acquisition and analysis, supporting the recognition and processing of commands from users. This technology is integrated in voice control systems such as virtual assistants, smart speakers, and smart home devices, making human-machine interaction more natural and convenient.
• Audio Recording Equipment: In recording devices such as voice recorders, mobile phones, and digital recording devices, sound sensors are the key component. It helps record audio with high accuracy, meeting the needs of personal note-taking to archiving professional recordings.
• Sound System: In audio systems such as home stereos, car sounds, or stage sounds, sound sensors are used to adjust the volume, sound balance, and other settings. This helps to optimize sound quality,  providing a richer and more vivid listening experience.
• Security and Alarm Systems: Sound sensors are integrated into security systems to detect unusual sounds such as loud noises, explosions, or bangs. When a problem is detected, the system will trigger an alert or send an instant notification to ensure safety.
• Positioning and Distance Measurement Systems: Sound sensors are also used in positioning and distance measurement devices such as acoustic radars, navigation systems in limited visibility, and measurement devices in industry and robotics. This application helps to increase accuracy and efficiency in operations that require measurement and monitoring.

These applications demonstrate the versatility and wide applicability of sound sensors, contributing to improved performance and user experience in a variety of fields.

5. Conclusion

It can be seen that sound sensors not only bring many utilities in daily life but also open up application opportunities in many modern industries. With the benefits that sound sensors bring, mastering the knowledge of this technology will help businesses make the most of the potential to apply them to other digital technology products in the future.

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