How to check the bottom microphone on a Xiaomi smartphone: from diagnosis to repair

The bottom microphone problems on Xiaomi smartphones are one of the most common malfunctions, which can manifest in many ways, from the complete absence of sound when calling to distorted noises during recording voice messages. Unlike the top microphone (responsible for noise cancellation), the bottom microphone is used for basic voice input, so its incorrect operation makes the device almost unsuitable for calls.

Many users mistakenly believe that the problem lies in the software or settings, but in 70% of cases, mechanical damage is to blame: moisture, dust or physical displacement of contacts after a fall. In this article, we will analyze 5 reliable ways to check, from simple tests using standard applications to deep diagnostics through engineering menus and hardware tests.

Important: If you notice that the person you are talking to is only hearing poorly when calling on VoLTE or via instant messengers, the problem may not be in the microphone, but in the network settings. In this case, first check the section about VoLTE at the end of the article.

Before you start testing, make sure that:

• 🔇 On the smartphone, the mode “Do not disturb” or “No sound” is not activated (check the slider in the notification curtain).
• 🔌 The device is not connected to a Bluetooth headset or external microphone (turn off all accessories).
• 📱 The latest version is installed on the phone. MIUI (Update the software through Settings → The phone. → Updating the system).

1. Verification through the standard application "Dictophon"

The fastest way to diagnose is to use a built-in voice recorder, which is suitable for all Xiaomi models, including the Redmi Note 12, POCO X5 and Mi 11, as the application is preinstalled in MIUI.

Open the Dictophone app and press the record button. Speak to the bottom microphone (located next to the connector). USB-C) 5-10 cm. After recording stop, listen to the recording:

• ✅ Clear sound without interference – the microphone is working correctly.
• 🔊 Muffled or quiet sound – possible clogged grille or membrane damage.
• 🚨 Crackling, hissing, distortions – contact problems or moisture under the microphone.
• 🔇 No sound – malfunction of microphone or motherboard.

If the record is not played at all, check the application permissions: go to Settings → Annexes → Dictaphone → Permits and enable access to the microphone.

💡

For a more accurate diagnosis, compare the recording from the bottom microphone and the top (during the call). If the top one is working normally and the bottom one is not, the problem is precisely in the hardware.

2. Testing by calling to another phone

This method will help identify problems that only occur during voice communication, ask a friend or use a second phone for a test call.

1. Speak to the bottom microphone (do not press the phone to your ear – keep it 1-2 cm from your mouth).
2. Switch to speaker (speaker) and repeat the phrase.
3. Activate Noise Cancel mode in the call settings (if available).

Evaluate the sound quality of the interlocutor:

⚠️ Note: If problems only occur when calling via VoLTE (icon) 4G/HD during the call, try to disable this function in Settings → SIM-maps and mobile networks → Call VoLTE and restart the phone. Sometimes firmware bugs affect voice transmission.

3.Use of the engineering menu (#4636##)

The engineering menu allows you to check the hardware status of the microphone without third-party applications, a method that works on most Xiaomi models, but may not be available on some custom firmware devices.

To open the menu:

1. Open the Phone app and enter the combination: ##4636###.
2. Select "Phone Information" (or Phone Information).
3. Scroll down to the Audio block and press the Microphone Test.

In this section you will see two microphones:

• Primary Mic is the bottom microphone (main microphone for calls).
• Secondary Mic is the upper microphone (for noise reduction).

Speak to the bottom microphone and watch the sound level indicator. If the band is not responding or shows zero, the microphone is faulty. On some models (for example, the Redmi Note 10 Pro), the engineering menu may display an error "Mic Loopback Test Fail" - this is a direct sign of hardware failure.

Close all background applications|Turn off Bluetooth and headphones|Make sure your phone is not connected to the charger.|Check the battery level (minimum 20%)-->

4. Diagnostics via code ##6484## (MTK Engineer Mode)

For smartphones with MediaTek processors (e.g. Redmi) 9A, POCO M3) Available extended microphone test through MTK Engineer Mode: This method gives more detailed information, including frequency characteristics.

Instructions:

1. Enter the dialer: ##6484##.
2. Select "Hardware Testing" → "Audio" → "Mic Test".
3. Press "Start Test" and speak to the bottom microphone.

The screen will show:

• 📊 Frequency response schedule – if the line is flat, the microphone is stable.
• 🔊 Signal Level (dB) – Normal: 60–80 dB in loud speech.
• ⚠️ Errors: Messages like “Mic Short” or “No Input” indicate a chain break.

If the test ends with an error, try repeating it after you restart your phone. MIUI affect the results of the diagnosis.

5. Verification with the help of third-party applications

If standard methods do not give a definite result, install specialized utilities for testing the microphone.

1. "Microphone Test" (by Keuwlsoft)

• 🎤 Shows the signal level in real time.
• 📈 Visualizes frequency spectrum (useful for detecting distortions).
• 🔄 Comparison of upper and lower microphones.

2. "Sound Meter" (by Smart Tools)

• 📏 Measures the volume level in decibels (dB).
• 🔍 Helps detect weak signal (normal: 65-75 dB in loud speech).
• 📊 Keeps the history of measurements for comparison.

3. "Phone Doctor Plus"

• 🩺 Complete diagnosis of all sensors, including microphones.
• 📋 Generates a report with an assessment of performance.
• 🔧 Tests the microphone in different scenarios (call, recording, noise cancellation).

Check reviews before installing, some apps may contain ads or ask for unnecessary permissions, and the best option is the “Microphone Test” – it is free and does not require registration.

⚠️ Attention: If all the tests show that the microphone is working, but the interlocutors still can't hear you well, the problem may be the network settings of the operator. SIM-If the problem persists, contact the operator to check the quality of communication.

Visual inspection and cleaning of the microphone

If software tests have confirmed a malfunction, proceed to visual diagnostics.The bottom microphone on Xiaomi smartphones is usually located:

• 📱 Right of the connector. USB-C (most models).
• 🔊 Under the speaker grille (on some devices, for example, Mi 11 Ultra).
• 🕳️ In a separate hole next to the main chamber (rarely).

For the inspection you will need:

• 🔦 Lantern (for illumination of the hole).
• 🔍 Loop (to check for dust and moisture).
• 🧹 Soft brush or compressed air canister.

Clean the microphone grille carefully:

1. Blow out the dust with compressed air (hold the balloon vertically to avoid moisture).
2. If dirt is visible, use a dry soft brush (do not use alcohol or liquids!).
3. Check if the microphone’s metal body is bent (this can happen after a fall).

If the microphone doesn't work after cleaning, it's probably a problem with the plume disconnecting or the contacts corrosion, and you'll need to disassemble the device.

💡

Before disassembling the phone, be sure to back up the data and turn off the battery (if possible). Damage to the plume during self-repair can lead to a complete loss of service of the device.

Additional: Microphone problems with VoLTE

VoLTE technology (voices through voices) 4G) Sometimes conflicts with the microphone on Xiaomi smartphones. If you notice that the interlocutor does not hear you well only when active VoLTE (icon) HD or 4G When you call, try the following steps:

1. Turn off VoLTE:

• Go to Settings. → SIM-maps and mobile networks.
• Choose yours. SIM-Deactivate the option "Call by VoLTE".
• Restart your phone and check the quality of the connection.

2. Reset the network settings:

• Go to Settings. → SIM-maps and mobile networks → Resetting network settings.
• Confirm the reset and wait for automatic re-registration in the network.

Update the firmware:

Some VoLTE bugs are being fixed in new versions MIUI. Check for updates in Settings → The phone. → Updating the system.

If the quality of communication has improved after the VoLTE shutdown, but you want to use this feature, contact Xiaomi Support with the phone model and firmware version.

FAQ: Frequent questions about the microphone on Xiaomi