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IoT product microphone air tightness test application note
1、Overview
Iot is the abbreviation of the Internet of Things, which refers to the combination of various information sensing devices, such as radio frequency identification, infrared sensors, GPS, laser scanners, etc. Connect all items to the network for information exchange and communication, which is easy to identify and manage.
1.1、Smart wear IoT products
So far, the Internet of Things has made our lives more and more convenient. From eating and clothing to traveling and shopping, the Internet of Things is slowly embedded in our lives. The smart wearable device is an important part of it. In the IoT era, smart wearable devices have more and more functions. At the same time, based on the iterative update of Bluetooth transmission technology, the low power consumption brought by it further improves the performance of smart wearable devices, among which representative products: TWS earphones, smart watches, smart speakers, etc.
Usually, when using the product, it is inevitable to come into contact with water such as sweat and rain, which will cause the acoustic performance of the product’s microphone to be damaged or degraded, and the user experience will be reduced.
Then for the test of product microphone airtightness, we have a complete system from the software test algorithm to the hardware test equipment, which can quickly and accurately present the data of the product microphone airtightness test items in a visual way.
2、Microphone air tightness application test for smart wearable IoT products
2.1、Smart wearable IoT product microphone airtightness standard test configuration
U 982 Bluetooth Adapter Features:
Support SBC\aptX Bluetooth protocol. (MegaSig also provides other models of Bluetooth adapters that support AAC\LC3\BLE\LHDC and other Bluetooth protocols)
Supports audio services such as A2DP, HFP (Narrowband, Wideband)
Support SPP data transmission
M 663+A 802 free-field microphone characteristics:
Prepolarized free-field measurement microphone for measuring the undistorted real sound pressure before the microphone is placed in the sound field
PM 6143 Audio Data Acquisition Card Features:
4 channels output, 4 channels input
Built-in amplifier and built-in ICP power supply circuit
MegaSig private drive, more stable test
AudioExpert audio analysis software features:
Complete Audio Analysis Algorithm Library
Supports automatic sequence editing
Support LabVIEW call
Support for remote control
AM 581 artificial mouth features:
Accurately simulate the sound source of the sound field near the human mouth, suitable for frequency response, distortion and other acoustic parameter testing of telephone microphones and microphones (microphones)
Higher low frequency transducer efficiency (especially 100-200Hz)
Extremely high sensitivity across the entire frequency band
Airtight custom fixture features:
Test data is true
more stable testing
2.2、Smart wearable IoT product microphone airtightness test link
(1) Take the airtightness test link of the TWS earphone as an example:
Airtightness test of microphone acoustic performance:
The fixture is not in action: the TWS earphone is connected and interacted with the U 982 Bluetooth adapter. AudioExpert pushes the audio signal to the PM 6143 audio data acquisition card and then sends out the sound signal through the AM 581 artificial mouth. The TWS earphone microphone collects the signal through the U 982 through the Bluetooth HFP protocol. The bluetooth adapter is sent back to AudioExpert audio analysis software for signal analysis.
Fixture action: The TWS headset is connected and interacted with the U 982 Bluetooth adapter, the cylinder controls the fixture to block the TWS microphone, and then AudioExpert pushes the audio signal to the PM 6143 audio data acquisition card, and then sends out the sound signal through the AM 581 artificial mouth, TWS headset microphone The collected signal is sent back to the AudioExpert audio analysis software through the Bluetooth HFP protocol through the U 982 Bluetooth adapter for signal analysis, and the difference calculation between the two test curves is carried out through the AudioExpert software, and finally the airtightness effect is obtained.
Loudspeaker routine acoustic performance test:
The TWS earphone is connected and interacted with the U 982 Bluetooth adapter, and the audio signal is pushed by AudioExpert through the Bluetooth A2DP protocol to make the speaker of the finished earphone vibrate, and the CM 311 acoustic coupling chamber + A 803 preamplifier microphone kit collects the signal to the PM 6143 audio data acquisition card, and then Send the collected signal back to AudioExpert audio analysis software for signal analysis.
(2) Take the airtightness test link of the smart watch as an example:
Airtightness test of microphone acoustic performance:
The fixture is not in action: the smart watch is connected and interacted with the U 982 Bluetooth adapter. AudioExpert pushes the audio signal to the PM 6143 audio data acquisition card and then sends out the sound signal through the AM 581 artificial mouth. The smart watch microphone passes the collected signal through the U 982 through the Bluetooth HFP protocol. The Bluetooth adapter is sent back to the AudioExpert audio analysis software for signal analysis.
Fixture action: the smart watch is connected and interacted with the U 982 Bluetooth adapter, and the jig is controlled by the cylinder to block the microphone of the smart watch, and then AudioExpert pushes the audio signal to the PM 6143 audio data acquisition card, and then sends out the sound signal through the AM 581 artificial mouth, the smart watch The microphone sends the collected signal back to AudioExpert audio analysis software through the Bluetooth HFP protocol through the U 982 Bluetooth adapter for signal analysis, and uses the AudioExpert software to perform difference calculations between the two test curves to finally obtain the airtightness effect.
Loudspeaker routine acoustic performance test:
The smart watch is connected and interacted with the U 982 Bluetooth adapter, and AudioExpert pushes the audio signal through the Bluetooth A2DP protocol to make the speaker of the finished earphone vibrate. Return to AudioExpert audio analysis software for signal analysis.
(3) Take the airtightness test link of the smart speaker as an example:
Airtightness test of microphone acoustic performance:
The fixture is not in action: the smart speaker is connected and interacted with the U 982 Bluetooth adapter, and AudioExpert pushes the audio signal to the PM 6143 audio data acquisition card, and then sends out the sound signal through the AM 581 artificial mouth. The Bluetooth adapter is sent back to the AudioExpert audio analysis software for signal analysis.
Fixture action: The smart speaker is connected and interacted with the U 982 Bluetooth adapter, the cylinder controls the fixture to block the microphone of the smart speaker, and then AudioExpert pushes the audio signal to the PM 6143 audio data acquisition card, and then sends out the sound signal through the AM 581 artificial mouth. The microphone transmits the collected signal to the AudioExpert audio analysis software through the Bluetooth HFP protocol through the U 982 Bluetooth adapter for signal analysis, and performs the difference calculation of the two test curves through the AudioExpert software to finally obtain the airtightness effect.