Owners of Xiaomi Redmi 4 smartphones often face a situation where the interlocutor stops hearing the owner of the device, or the sound becomes intermittent and quiet. In most cases, the problem lies not in the software failure, but in the physical location or contamination of the recording element. Understanding the exact configuration of the audio system of this model is critical for the correct diagnosis of the malfunction.
The Redmi 4 (including the Prime and Pro versions) is built on an aluminum unpainted body, which dictates specific engineering solutions for output. Unlike plastic counterparts, the microphone holes are made in the form of neat drills in metal that are easily clogged with dust, pile from the pocket or oxidized when moisture is ingested. The main microphone is located at the bottom of the front panel, directly next to the charging socket, which makes it vulnerable.
But that's just the tip of the iceberg, because the system has two microphones to implement noise reduction technology, and if you try to clean the bottom hole and the problem is in the top sensor, the result is zero, and then we'll go into detail about the audio architecture of your smartphone and how to restore performance.
The architecture of the Redmi 4 audio system
Xiaomi Redmi 4 has two microphones that work in tandem, which is the standard configuration for modern devices, which allows you to implement the Noise Cancellation function. The first element, which is called the main one, is responsible for transmitting your speech during a conversation or recording voice messages in messengers, which is what perceives sound when you hold the phone to your ear.
The second element, often called secondary or noise suppression, plays a supporting but important role: it analyzes background noise and transmits data to a processor that programmatically cuts out extraneous sounds from your voice, and the arrangement of these elements is not accidental: they are spaced on opposite ends of the body to create a stereo effect when recording noise and more accurately determine the direction of the sound source.
It's important to understand that in MIUI software, these devices can be displayed in different ways. When tested through an engineering menu or third-party microphone-checking apps, they often appear as Primary Mic and Secondary Mic. Damage to either of them affects overall communication quality, although in normal conversation mode you may not immediately notice the secondary sensor failing.
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Use a voice recorder in a quiet room to check the main microphone, and to check the secondary, turn on the video recording on the rear camera in a noisy place.
Exact location of the main microphone
The main recording element on Xiaomi Redmi 4 is on the bottom end of the device. If you flip the smartphone with the screen to yourself and look at the bottom edge, you will see symmetrical holes on the sides of the charging port Micro-USB. The left hole (when viewed from the bottom) is the speaker, and the right one is the input for the main microphone. In some board revisions, the hole can be shifted closer to the center, but always remains in the lower third of the case.
Structurally, this is a small circular hole about 1 millimeter in diameter, and it has a protective net inside it that prevents large dust from entering the module, and it is this mesh that most often causes bad sound by being clogged with fine dust or compressed from moisture. Visually, the pollution can be invisible to the naked eye, so you need to be carefully examined in good light.
If you use a safety glass or film with an incorrect cutout, they can cover part of this hole. Even a minimal displacement of the protective coating by 0.5 mm can significantly reduce the sensitivity of the microphone, creating a "conversation from the barrel" effect. Make sure that the cutouts of the accessories match perfectly with the technical holes of the case.
☑️ Diagnostics of the bottom microphone
Where is the second (noise-suppressing) microphone located?
The second microphone, which is responsible for cutting off noise, is located on the top end of the smartphone. On Redmi 4, this hole is located next to the 3.5 mm headphone jack and the IR port. SIM-cards or simply do not pay attention to it, considering a decorative element.
When you call in speakerphone, the main microphone turns off, and it's the top sensor that comes in, and if the person hears you well in normal mode, but stops hearing when the speakerphone is on, the problem is localized in the top hole, and this microphone is also actively used when shooting video on the main camera.
⚠️ Warning: When cleaning the top microphone, be extremely careful. There is an IR port next to it, and aggressive cleaning or liquid intake can damage the infrared diode, after which the remote control will stop working.
The design of the upper microphone is similar to the lower one, but due to its location, it is less likely to be clogged with pocket dust, but more often suffers from cosmetics (if the phone is in your purse) or sweat. In winter, respiratory condensation can also temporarily block the work of this element until it completely drys out.
Table: Comparison of microphone functions
For a better understanding of the Xiaomi Redmi 4 audio system, consider a comparative table describing the purpose and modes of operation of each element.
| Characteristics | Main microphone (lower) | Additional microphone (Upper) |
|---|---|---|
| Location. | Lower end, right of charge | Upper end, next to jack 3.5 |
| Substantive function | Recording of speech on a regular call | Noise suppression and loud communication |
| Use in cells | Recording of sound in the camera annex | Video recording |
| Frequency of breakdowns | High (dust, moisture, impacts) | Medium (oxidation, cosmetics) |
The table shows that the main microphone is used in most use cases, making it a priority for testing for any sound problems, but you can not ignore the top sensor, because its malfunction can lead to distortion of the voice and echo.
Causes of malfunctions and diagnostic methods
Why does the Redmi 4 microphone stop working? The most common, but common, reason is a software failure of an audio driver or an application conflict. You need to run a software diagnostic before you take the phone apart or carry it to the service. There's a powerful engineering tool built into the MIUI shell to test the hardware.
To run the test, you need to go to the dial menu and enter the code ##6484##. In the CIT (Customer Information Test) menu, you should find the Receiver or Microphone option. The system will ask you to say a phrase and write it down, and then play it. If the record is clean, there is a problem in the software or a specific application (for example, in the Viber or Telegram permission settings).
If the engineering test doesn't sound, or wheezes, or interrupts, it's a hardware problem.
- 🧹 Pollution of the protective net by dust or pile.
- 💧 Oxidation of microphone contacts due to moisture.
- 🔌 The departure of the plume from the fee (relevant after the falls).
- 💥 Physical shock that damaged the microphone membrane.
If the phone has recently fallen, there is a high probability of a breach of the plume contact. On Redmi 4, the microphone module is often integrated into the bottom charging plume or connected by a separate connector. The shaking of the device can temporarily restore contact, which will confirm the exiting plume version.
What to do if you pass the test, but can’t hear it on Skype?
Instructions for cleaning and maintenance
If the diagnosis shows a hardware problem related to contamination, you can try to clean the microphone yourself. For the Xiaomi Redmi 4, this process requires accuracy due to the metal body. You will need a soft toothbrush, isopropyl alcohol (or a special liquid for cleaning electronics) and a pear for purging.
Do not use sharp objects such as needles or pins to pick through the microphone hole. You risk piercing the protective membrane or damaging the sensory element itself, which will lead to irreversible damage. It is also forbidden to use compressed air from high pressure canisters - the jet can damage the internal components.
⚠️ Warning: Before any cleaning, be sure to turn off your smartphone. The hitting of conductive fluid (even alcohol) on the board will cause a short circuit.
The cleaning technique is to moisten the brush lightly with alcohol (it should be wet, but not wet) and walk gently through the microphone hole in circular motions. Let the alcohol evaporate for 2-3 minutes. Then use the pear to blow out the softened dust. Repeat the procedure for the upper and lower microphones.
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Regular preventive cleaning of microphone holes with a dry brush once a month prolongs the service life of the audio system by 30-40%.
Replacement of microphone: technical nuances
If cleaning didn’t work, you need to change the microphone. On the Xiaomi Redmi 4, the main microphone is often soldered on the bottom plume, which also includes a charging connector and a conversational speaker. This makes repair easier: changing the plume as a whole, you simultaneously update both the microphone and the charging connector, which also often wears out.
To replace you will need to remove the back cover (it is held on two screws under plugs). SIM-And on the latches around the perimeter, unscrew the plastic speaker frame and disconnect the plume. The top microphone can be output by a separate wire or also integrated into the overall circuit. When buying a spare part, pay attention to compatibility with your version of the board, as in different revisions of Redmi 4 layout may differ.
After the replacement, it is recommended to take the test again in the engineering menu ##6484## to make sure that the new module is correctly installed. If the sound appeared but became quieter than it was before, perhaps a microphone with a different sensitivity was used in the new plume, which is the norm for non-original parts.