The microphone on Xiaomi 9 smartphones (including Mi 9, Mi 9 SE, Mi 9T and Redmi Note 9 models) is a critical component that affects the quality of calls, recording voice messages and voice assistants. If the interlocutor complains that he does not hear you well, or applications like Google Assistant do not respond to voice commands, the problem can be a hardware malfunction, software failure or incorrect settings.
In this article, you will find 5 proven ways to diagnose a microphone, from standard MIUI tools to third-party applications and service codes. We will also analyze the typical causes of problems (for example, contamination of the Type-C connector on the Mi 9T can block the second microphone) and give recommendations for their elimination. If after tests the problem remains, at the end of the article you will find a checklist to prepare the phone for repair.
1. Checking the microphone through the built-in voice recorder
The easiest way to test the microphone is to use the standard Dictaphone app, which is pre-installed on all Xiaomi smartphones with a MIUI shell. This method does not require installing additional software and takes less than a minute.
How to run the test:
- 📱 Open the Dictaphone app (the microphone icon on the desktop or in the application menu).
- 🎤 Press the recording button (usually red) and say the phrase 10-15 cm from the bottom of the phone (where the main microphone is located).
- 🔊 Stop the recording and listen to it. If the voice sounds clear, without wheezing or interference, the microphone is working correctly.
- 🔄 Repeat the test by covering the top of the phone with your finger (there is a second microphone for noise reduction). If the sound is quieter or gone, both microphones function.
If the recording is not playing or the sound is severely distorted, move on to the next method. Note: on the Mi 9T and Redmi Note 9 Pro, when recorded in a noisy room, automatic noise cancellation can be triggered, which is normal, but sometimes it eats up a useful signal.
⚠️ Attention: On some firmware MIUI (Especially global versions, the Dictaphone application may not be available, in which case use the alternative - Google Recorder (available on the Play Market).
2. Testing through a call or voice message
If the recorder showed a normal recording, but the interlocutors still do not hear you when talking, the problem may lie in network settings or software restrictions, this will help to check the test call or sending a voice message.
Instructions:
- Call another phone (preferably via WhatsApp or Telegram to rule out carrier issues).
- During the conversation, switch to speakerphone – if the sound is clearer, the problem is with the speaker, not the microphone.
- Send a voice message in the messenger and listen to it on another device.
If the voice in the message is distorted, and during the call the interlocutor hears you intermittently, check:
- 📶 Network quality: weak signal 4G/5G may cause a sound to break.
- 🔇 Microphone settings in the app: on WhatsApp go to Settings → Warehouse and data → Permits → Microphone.
- 🛠️ Updates: In some versions MIUI 12–14 was a microphone bug during VoIP calls (fixed in patches from 2023).
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If you hear clicks or cracks during the call, try turning off the Voice Improvement feature in your phone settings: Settings → Sound → Call quality.
3. Use of service codes for diagnostics
Xiaomi smartphones support hidden service codes that allow you to test hardware components, including a microphone.These codes work on most Mi 9 models, but may vary depending on the version of MIUI and the firmware region.
The basic codes for checking the microphone:
| Code. | Description | Works on |
|---|---|---|
| ##6484## | Microphone test (shows signal level in dB) | Mi 9, Mi 9 SE, Redmi Note 9 |
| ##4636## | Test menu (select Information → Microphone) | All models in MIUI 11-14 |
| ##36446337## | Advanced diagnostics (includes microphone and speaker test) | Mi 9T, Redmi Note 9 Pro |
How to use the codes:
- Open the Phone app and enter the code as a number.
- In the menu that appears, select the Microphone Test section or similar.
- Speak to the microphone – the screen should display a sound wave or digital values (for example, 70-90 dB at normal volume).
⚠️ Note: On some firmware (for example, MIUI EU) Service codes may be disabled, in which case use testing applications (see next section).
What if the code doesn't work?
4. Third-party applications for deep diagnostics
If the built-in tools don't give you a clear answer, use specialized applications that allow you to test the microphone for sensitivity, frequency range and signal delay.
Top.-3 apps 9:
- 📊 Microphone Test (by Smart Tools) – shows the graph of sound waves and noise level.
- 🎛️ Sound Meter – Measuring volume in decibels (useful for comparison with reference values).
- 🔧 Phone Doctor Plus – comprehensive diagnostics, including a test of microphone and speakers.
How to interpret the results:
- 📈 Normal signal strength during conversation: 60-90 dB.
- 🚫 No signal or value below 30 dB is a sign of microphone malfunction.
- 🔄 Sharp surges in schedule – possible problems with contacts or noise cancellation.
Examples of Microphone Test:
- Install an app from the Play Market.
- Run the test and speak into the microphone at a distance of 5-10 cm.
- Compare the chart with the reference (the app usually shows the green zone of normal values).
☑️ Preparation for the microphone test
5. Hardware check: what to do if the microphone is not working
If software tests show a malfunction, the cause may be:
- 🔌 Type-C connector contamination (on Mi) 9T Redmi Note 9 Pro second microphone is located next to the connector).
- 💧 Moisture intake - even after drying, the oxidation of contacts can manifest itself in months.
- 🛠️ Mechanical damage (for example, after falling or disassembling the phone).
- 🔋 Motherboard malfunctions (less commonly but possible audio codec problems).
Self-diagnosis:
- Check the Type-C connector for dirt or oxidation. Clean it with a plastic toothpick (not metal!).
- Check if the microphone is covered with a cover or film (especially for the Mi 9 SE with a thin body).
- Connect headphones with a microphone – if they work, the problem is with the phone’s main microphone.
⚠️ Warning: If the phone fell or came into contact with water, don’t try to disassemble it yourself – on Xiaomi 9, microphones are soldered to the board, and replacing them requires a soldering station and experience.
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On the Redmi Note 9 and Mi 9T, the second microphone (for noise cancellation) most often fails due to its close location to the Type-C connector.
6. Resetting and flashing
If the microphone was working before, but stopped after updating or installing applications, the problem may be software, in which case resetting or flashing will help.
How to reset your settings without losing data:
- Go to Settings → About the phone → Reset settings.
- Select Network Settings Reset (this will delete saved Wi-Fi passwords, but will not affect files).
- Restart your phone and check the microphone.
If the reset didn’t help, try rolling back the update or reflashing the phone:
- 📱 Download the latest stable firmware for your model from the official Xiaomi website.
- 🔄 Use the Mi Flash Tool to Fastboot Firmware.
- 🔧 After the firmware, reset to factory settings (Settings) → Additionally. → Recovery and discharge).
Important: Before firmware, back up your data through Settings → Additional → Backup and Reset.
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If the microphone stopped working after upgrading to MIUI 14, try to roll back on MIUI 13 - some builds had bugs with audio drivers.