How to increase the volume of the microphone on Xiaomi Redmi 9: from simple settings to hidden features

Owners of Xiaomi Redmi 9 often face a problem: the interlocutor does not hear voice during calls, and voice messages are recorded too quietly, the reasons can be due to hardware limitations (polluted microphone, damaged connector) and software settings, in 80% of cases, the problem solves the adjustment of the microphone sensitivity parameters or cleaning the system cache.

This article covers all working methods, from basic (volume control in call settings) to advanced (modification through EngineerMode or ADB), and we will also discuss how to check the microphone performance and avoid typical setup errors. If after all the manipulations the sound remains weak, at the end of the article you will find a checklist for hardware malfunctions.

The reasons for the low volume microphone on Redmi 9

Before you start setting up, it's important to understand why the microphone is quiet, and here are the most common reasons:

• 📱 Systemic constraints MIUI: By default, firmware MIUI Reduces the sensitivity of the microphone to suppress noise, which sometimes leads to excessive silence of the voice.
• 🔊 Incorrect call settings: The call menu can be activated mode "Silent microphone" or voice amplification disabled.
• 🧹 Microphone hole contamination: Dust, fibers of fabric or moisture block sound waves, reducing recording quality.
• 🔄 Failures after update: Updates MIUI Sometimes reset audio settings or make bugs in audio processing.
• 🛠️ Hardware malfunctions: Microphone module damage, contact oxidation, or antenna problems (for the main microphone).

The first four are software-based, the last one requires repair. To rule out hardware problems, first check the microphone with a built-in voice recorder or third-party applications (like Voice Recorder). If the recording is quiet everywhere, it's a system problem. If only during calls, the phone settings are to blame.

Method 1: Increase the volume of the microphone in the settings of calls

The easiest method is to use built-in MIUI options to adjust the sound during a conversation, which does not require superuser rights and works on all versions of the firmware.

1. Open the phone application and go to ⋮ (Menus) → Settings.
2. Select Sound and vibration during the call (in some versions of MIUI, Sound Settings).
3. Activate the voice enhancement or noise suppression slider (if it is turned off).
4. Check if the mode is on. HD-Voice (VoLTE) – improves sound transmission in networks 4G.

If these options are not available, try an alternative path:

1. During an active call, click on the speaker icon in the top menu.
2. In the window that appears, find the microphone icon and move the volume slider to the right.

Make sure the "Do Not Disturb" mode is off |

Check if the "Silent microphone" mode is activated in the special features settings |

Turn off Bluetooth headphones (they can intercept the microphone) |

Reboot your phone after the changes-->

⚠️ Attention: On some firmware MIUI 12+ Voice amplification is hidden. If it's not on the menu, try resetting the Phone app to Settings. → Annexes → Application management → Phone. → Warehouse → Clear the data.

Method 2: Use of Engineering Menu (EngineerMode)

The engineering menu allows you to manually adjust the microphone settings, including signal amplification and sensitivity, a method that requires caution — the wrong settings can degrade the sound quality.

1. Open the Phone app and enter the combination: ##4636##.
2. In the menu that appears, select Phone Information (or Phone Information).
3. Scroll down to the Audio block and press the Microphone.
4. In the Mic Gain field, set the value from 150 to 200 (usually 100 by default).
5. Save the changes and restart the phone.

If #4636### doesn’t work, try the alternative code.

#36446337## (for audio testing)


or


#6484## (for microphone test)

⚠️ Warning: Changing the Mic Gain settings above 200 can cause distortions (wheezing, interference).If after settings the interlocutor complains about the "metal" voice, return the value to 150.

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Before you change the settings in the engineering menu, write down the current values on paper, which will help you to return the settings if the sound quality deteriorates.

Method 3: Cache cleaning and resetting sound settings

Sometimes the problem lies in corrupted cache files of system applications that process sound, and cleaning the cache and resetting the settings can return the microphone to factory parameters.

1. Go to Settings → Applications → Application Management.
2. Find and open apps: Phone Contact Google Play Services (if used)

Warehouse → Clear the cache

Phone.

Clear the data

Reboot the phone.

If cleaning the cache did not help, reset the sound settings:

1. Go to Settings. → Sound and vibration.
2. Press. ⋮ (Menus) → Reset the settings.
3. Confirm the action and restart the device.

Method 4: Configure with ADB (for advanced users)

If standard methods don’t work, you can change the microphone settings via Android Debug Bridge (ADB), which requires a computer and basic command line knowledge.

Preparation:

1. Download and install ADB Tools on PC.
2. On your phone, activate Developer Mode: go to Settings → About Phone → MIUI version and press 7 times.
3. Return to Settings → Additional → For developers and enable USB debugging.
4. Connect Redmi 9 to your PC and confirm debugging permission.

Commands to increase the volume of the microphone:

adb shell settings put global mic_gain 200


adb shell settings put global voice_call_mic_gain 180




adb shell settings put global voip_mic_gain 180

To make the changes effective, restart your phone:

adb reboot

⚠️ Attention: Teams ADB If you have heard any sound artifacts (echoes, distortions) after the reboot, return the values to the standard: adb shell settings delete global settings mic_gain adb shell settings delete global voice_call_mic_gain

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Use ADB only if other methods have failed. Incorrect commands can disrupt the audio system.

Method 5: Checking and cleaning the hardware

If the software methods failed, the problem could be physical contamination or damage to the microphone.The Xiaomi Redmi 9 has three microphones:

• 🎤 Main microphone (lower part of the body, next to the connector) USB-C) — call-in.
• 🎤 Second microphone (top, next to the speaker) – for noise reduction.
• 🎤 Third microphone (in the main camera module) - for video.

How to clean the microphone:

1. Turn off the phone and remove it. SIM-map.
2. Take a soft toothbrush (or makeup brush) and gently clean the microphone holes.
3. To remove moisture, use silica gel (shoe box bags) - put the phone in a sealed bag with silica gel for 12 hours.
4. Do not use compressed air or sharp objects – this can damage the microphone membrane.

If the sound does not improve after cleaning, check the microphone for damage:

• Hold the phone to your ear and call another number – if you hear crackling or no sound at all, the microphone is faulty.
• Try recording your voice in a quiet room: if the recording is accompanied by constant hissing, there may be a problem with contacts.

Additional Advice and Frequent Mistakes

Even after successfully setting up the microphone, users often experience recurrences of the problem.

• 🔄 Update the firmware: In new versions MIUI Audio drivers bugs are being fixed. Check the updates in Settings. → The phone. → Updating the system.
• 🚫 Avoid “optimizers”: Apps like Clean Master or DU Speed Booster can delete important cache files responsible for sound.
• 🎧 Check accessories: If you use wired headphones with a microphone, the problem may be a 3.5 mm connector (on the Redmi 9, it often oxidizes).
• 📶 Monitor the network signal: In low-course areas, the operator can automatically reduce the quality of voice transmission.

Critical information: On some versions of MIUI 13+, after manually changing the microphone settings via EngineerMode or ADB, the system may reset them after rebooting. To fix the settings, install the Tasker application and create a task to re-use ADB commands when the device starts.

Checklist for fault diagnosis

If none of these methods worked, go through this checklist to narrow down the possible problems:

Check the microphone in 3 applications: Phone, Recorder, WhatsApp|

Make sure the headphones aren't the problem (disable Bluetooth and wired headsets)|

Test the phone in hands-free mode (if it works, the problem is in the main microphone)|

Try another one. SIM-The card (sometimes the operator blocks the card) HD-voice)|

Reset all settings to factory settings (Settings → Additional → Resetting)|

Check your phone for moisture (indicators) LCI tray-tray SIM-map)|

Update the firmware to the latest stable version-->

If all the points are checked and the microphone is still quiet, the most likely to be:

• Hardware malfunction of the microphone module (requires replacement).
• Problems with the motherboard (oxidation of contacts, damage to the audio track).

FAQ: Frequent questions about setting up the microphone