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 attendee detection, reduce noise in calls, and provide different audio logs 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 you to listen to music, watch TV, they are a game console, they record video and even record audio. Paradoxically, sound capture has evolved quite silently.
Generally, the more microphones, the better the audio quality.
Bottom microphone on the Samsung Galaxy Note 20 Ultra
More is usually indicative 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 contain the most microphones. And it’s for one main reason: they offer more audio features.
As much as we speak in the singular, telephones include more than one microphone. The usual thing is that they have a couple of them in order 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 acquires more nuance, 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 that many high-end mobiles already include, manufacturers they usually incorporate a fourth microphone on the back of the phone, in the area of the objectives. In this way the audio is captured in 360º; achieving videos with a sound closer to the scene that was recorded. You can even amplify the audio range as you zoom. This achieves greater realism.
Where are the mikes placed on the phone?
Micro next to the SIM tray (Xiaomi 11T). Who has not been to the wrong hole?
This question is impossible to answer categorically since each manufacturer position the microphones as you see fit and depending on how you’ve positioned the internal components. As each microphone needs an outlet to the outside, and since the microphone must be connected to the plates by means of a cable (usually 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 outlet to the outside
Look at your mobile. The usual thing is to have a microphone (or a couple of them) in the lower part of the device: sometimes with a hole and sometimes taking advantage of the output of external speakers; on the upper edge there is usually another hole for the third mic, the one related to noise cancellation (it is also used to be placed on the call handset); and in the rear area of the lenses there may be another hole for the fourth mic, the one dedicated to video recording.
Audio zoom in the Google Pixel 6 pro taking advantage of its rear mic
Each brand and model of mobile can place the microphones in a different place, even if the order that we have defined is usual. The number varies depending on the benefits: noise cancellation is usually included for calls; which triggers the inclusion of three microphones. If the mobile is a range with some specialization in video the fourth micro between the rear cameras is usually appreciated. There may even be more.
The voice assistant benefits from the increased number of mics: so you can hear commands from anywhere
Aside from improvements in recording quality, audio zoom, and noise cancellation, increasing the number of mics benefits the smart assistant. Have you noticed that a “Ok, Google” in a low voice 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 mikes, operating systems treat that hardware in a unique way. This is, applications will not be able to use them if the user denies them permission to access the microphone. Therefore, it is enough to block this permission for none of them to work.
From Android 11 the system warns with a green dot when the microphone is active; with a global management of audio capture in Android 12. Be aware of when the mics are used, and what software used them, it is a good way to protect privacy.