The principle of the microphone for noise cancellation in mobile
Today, any mobile device, whether smartphone flagship or low-end iPHONE with the chipset of middle or high level, are equipped with noise reduction systems. It is necessary to improve the quality of conversation on the street, in shopping centres with large human flow, airports, transport. These systems give priority to voice, separating useful signals from noise from other sources.
Negatively affect the sound of moving cars, planes, trains, and other noise equipment. Device active noise cancellation allows you to perceive the whole sound spectrum, subtract from the main conversation extraneous signals and to remove them.
When analyzing the performance of audio equipment with use of the silencer revealed some shortcomings. Chip weakly adjusted the sound during a call. It was not on the frequency of the human voice, but only stood out a roar and buzz of the cutting tool, the noise of the wind or the movement of the wheels of the trains. Active systems are not been able to distinguish voices of different people during a conversation in places with a deafening sounding music. Chipset not singled out the voice of speaking person on the phone.
However, IT does not stand still, they constantly moderniziriruyutsya. Now smartphones have become equipped with new, more modern systems of active noise suppression. Some models equipped with two microphones. One for transfer talk, the second to record a sound file. They immediately filter out signals whose frequency is, for example, less than 50 Hz and above 5 kHz. When muted uplift other frequencies the subscriber is not already available extraneous noise or audible, but very quiet.
the Principle of operation of noise suppression.
The second device is located on the upper end side or on the back of the smartphone, close to the main microphone. Its main role is in processing the incoming audio signal and the analysis frequency in both microphone channels. Chipset concentrates the information in memory and outputs the already processed from the noise of the voice of the user on the device software.
The function tone processor in the smartphone based on the spectral analysis of acoustic waves received from different microphones. Main «standard» is the main microphone. It is closer to your mouth, so is a particular priority. During a conversation with a contact chip noise reduction analyzes the volume of the audio signals at different frequencies and selects the strongest. He believes it is their noise, immediately mutes or significantly reduces.
Some mobile devices (e.g. iPhone 5, model 5s and 5c; Meizu Pro 5 and Xiaomi) is equipped with three microphones. Speakers are not the highest volume, but pure sound, without hoarseness. In the settings of the smartphones available functions «Improved sound Mi» (to do this, you select the types of headphones for setting the presets sound) and 7-band equalizer (from 60 Hz to 14 kHz). The sound volume in the headphones is high, the sound melodic. Supported formats are AAC 8 to 320 kbps, protected AAC to have files from the iTunes Store.
This innovation provided to improve the performance of noise cancellation. The user, receiving volume and clear sound, can not worry about the poor quality of the conversation. Chip sound ultracytochemical accurately determines the frequency and requires its strengthening. Extraneous sources of lightning are muffled at any ambient temperature and relative humidity.
The quality of communication and vibrate at such devices do not cause problems. Undoubtedly, the level of communication with subscribers increased significantly, but makes the phone much more expensive. However, sometimes it is not necessary to pay attention to it, and to buy such a model.