In general, we usually refer to the microphone of our mobile in the singular without this being really true: mobiles equip more than one microphone, usually two (and more). The purpose is to improve assistant detection, reduce noise in calls and offer different audio tracks in video recordings.
Despite how “small” a mobile phone is, so much technology is stored inside the device that smartphones have become a multidisciplinary tool. They call, they allow to listen to music, watch TVThey are a game console, they record video and even record audio. Paradoxically, sound capture has evolved quite quietly.
In general, the more microphones, the better the audio quality.
Bottom microphone on the Samsung Galaxy Note 20 Ultra
More is usually an indication that that particular aspect is better. Always in general terms, that direct proportionality has no effect on the number of cameras or the number of megapixels, for example. Even so, the best mobiles are the ones that contain the most microphones. And it is for one main reason: with it they offer more audio functions.
As much as we speak in the singular, phones include more than one microphone. The usual thing is that they have a couple of them to capture the audio from two different sources; achieving stereo sound for calls and also for voice recorder.
The number of microphones also affects the quality of the recorded sound since, by merging the different audio channels provided by the microphones on the same track, the resulting sound becomes more nuanced, captures lower frequencies and the mobile can reduce the noise obtained so that the track offers greater cleanliness. Always on paper, we already said that more does not mean better.
With professional video recording and audio zoom already included in many high-end mobiles, manufacturers they usually incorporate a fourth microphone on the back of the phone, in the goal area. In this way, the audio is captured in 360º; achieving videos with a sound closer to the scene that was recorded. It is even possible to amplify the audio log as it is zoomed. This achieves greater realism.
Where are the micros placed on the phone?
Micro next to the SIM tray (Xiaomi 11T). Who hasn’t been in the wrong hole?
This question is impossible to answer categorically since each manufacturer places the microphones as you see fit and depending on how you have placed the internal components. As each microphone needs an outlet to the outside, and the microphone must be connected to the plates by means of a cable (normally flex or flat), the interior design plays a decisive factor in the placement of the microphones.
The interior design of the mobile plays a decisive factor in the placement of the microphones: they must have an exit to the outside
Look at your mobile. The usual thing is to have a micro (or a couple of them) in the lower part of the device: sometimes with a hole and others taking advantage of the output of the external speakers; on the upper edge there is usually another hole for the third micro, the one related to noise cancellation (it is also usually placed in the call receiver); and in the rear area of the lenses there may be another hole for the fourth microphone, the one dedicated to video recording.
Audio zoom in the Google Pixel 6 pro taking advantage of its rear micro
Each brand and model of mobile can place the microphones in a different place, even if the order that we have defined is more than usual. The number varies depending on the benefits: noise cancellation is usually included for calls; which triggers the inclusion of three micros. If the mobile is a range with some specialization in video the fourth micro is usually seen between the rear cameras. There may even be more.
The voice assistant benefits from the increased number of microphones: so you can listen to commands from anywhere
Apart from improvements in recording quality, audio zoom and noise cancellation, increasing the number of micros benefits the smart assistant. Have you noticed that a soft “Ok, Google” is usually enough for the mobile to wake up and listen to you? The sensitivity, and the number of microphones, help to detect the voice from any angle around the mobile.
Disconnecting one microphone disconnects all
Rear microphone on the Google Pixel 6
Although they may have many micros, operating systems treat that hardware in unique ways. This is, apps will not be able to use them if the user denies them permission to access the microphone. Therefore, it is enough to block said permission so that none of them work.
From Android 11 the system warns with a green dot when the microphone is active; with global management of audio capture in Android 12. Keep track of when mics are used, and what software used them, it is a good way to protect privacy.