The Redmi Note 9 series has gained popularity due to its excellent performance at a reasonable price, but users often face an unpleasant surprise: in the dynamics, the interlocutor becomes difficult to hear. This can occur suddenly or increase gradually, turning important calls into a test. The problem is not always the breakdown of the device itself, often the fault of the settings of software filters or banal pollution.
In this article, we will take a look at all the possible causes of the volume reduction and suggest effective methods to eliminate them. You will learn how to adjust the noise cancellation, check the state of the speaker mesh and use hidden engineering menus for diagnosis. Ignoring this problem can lead to missing important calls, so it is worth checking the state of the audio system right now.
Program settings and operating modes
The first thing to check is the basic volume settings and active sound profiles. In the MIUI shell, you often find a situation where the system volume of media files is high and the volume of the call is set to a minimum. Make sure that the sliders in the Settings → Sound and vibration menu are twisted to the maximum for the "Call Sound" section.
Noise Reduction is a common cause of silent sound, and the algorithms used by Snapdragon processors sometimes work incorrectly, perceiving the voice of the interlocutor as background noise and suppressing it. Try turning this option off in the audio settings menu or during a call by pressing the volume button and selecting the appropriate mode.
⚠️ Warning: Disabling noise reduction can cause your voice to sound to the echoer in high winds or outdoors, but you will hear it much better.
You also need to look at pocket mode or cover use, and some security accessories overlap the bottom microphone or the main speaker, which can cause the sound balancing system to work, so take off the case and check if the volume has changed.
Physical contamination of speakers and microphones
The most common technical reason is the banal clogging of the speaker's grid with dust, pile from clothing or skin fat. The talk mesh in the Redmi Note 9 is located in a narrow gap above the screen where contamination enters regularly, and even a microscopic layer of dust can reduce the volume by 50-60%.
To clean, use a soft toothbrush with dry bristles. Carefully, without much pressure, walk along the speaker grid in circular motions. You can also use paint tape: glue it with a sticky side to the speaker and sharply tear it off to pull dust from the depths.
- 🧹 Use a soft brush to remove dust from hard-to-reach places.
- 🚫 Avoid sharp objects (needles, pins) to avoid damaging the membrane.
- 💨 Compressed air in cans can be used only with short "pushki" and at an angle, so as not to drive moisture inside.
Don't forget the bottom microphone, which is also responsible for your voice and noise cancellation, and if it's clogged, the system can automatically lower the overall volume due to incorrect feedback.
Set up the equalizer and Dolby Atmos
Xiaomi smartphones often pre-installed Dolby Atmos sound effects module or own equalizer MIUI Sound. Incorrectly selected profile (for example, "Cinema" or "Games") can cut out the frequencies on which the human voice lies, making speech indistinct and quiet.
Go to the sound settings and select the profile "Music" or "Standard." In the advanced equalizer settings, try manually lifting sliders in the mid-frequency range (about 1-3 kHz), which is where the main energy of speech is. If you use third-party applications to amplify sound, make sure that they do not conflict with the system settings.
Sometimes resetting the audio settings to factory values helps to return clarity.In the equalizer menu, find the reset button or simply switch the profile several times to update the audio drivers.
Effects of protective film and accessories
Many users don't pay attention to how the protective film or glass is glued. If the protective coating has a solid coating at the top of the screen, it can physically block the speaker's sound slit, which is especially true for narrow-frame models like the Redmi Note 9.
Check the top of the screen: if the film closes the speaker hole, the sound will be deaf and quiet. In some cases, it helps to carefully cut the hole in the film with a scalpel, but it is safer to replace the glass with a case-friendly model.
⚠️ Warning: Do not try to pierce the film with a needle over the speaker - there is a high risk of damaging the speaker or the screen under pressure.
Also check Bluetooth connections. If the phone thinks it's connected to a headset or speaker (even if they're off but within range), the sound can go there or mix, creating a quiet and intermittent effect.
Diagnostics through engineering menu and tests
For a deep diagnosis of audio tract in MIUI exists CIT-The Customer Interface Test is a built-in tool for engineers to test each component separately. To get there, type ##6484## in the Phone app".
In the test list, find items related to audio: "Receiver", "Speaker", "Main Mic" (main microphone) and "Sub Mic" (secondary microphone). Run the tests sequentially. If in "Receiver" mode you can barely hear the test sound at maximum volume, and in "Speaker" mode the sound is normal - the problem is in the upper speaker.
If the tests show error or no sound, software methods may not help, in which case it is worth considering the option of resetting to factory settings, saving the data beforehand to exclude software conflict.
Hardware malfunctions and repairs
If software and cleaning methods didn't work, there's a hardware malfunction. In the Redmi Note 9, there's a problem with the plume of the bottom speaker (which is often combined with the charging port) or the failure of the upper speaker speaker.
A common problem is the wear of the speaker membrane over time. If the phone is a few years old, the membrane may have coarsed or deformed, which physically limits the amplitude of the oscillations and reduces the volume.
| Symptoms. | Probable cause | Decision |
|---|---|---|
| The sound wheezes and interrupts. | Moisture or dust on the membrane | Cleaning, drying, changing the speaker |
| The interviewer can be heard very quietly, but the music is loud. | Failure of the conversational speaker | Replacement of the top speaker |
| It sounds, but it's very deaf. | Protective film or case | Accessories removed |
| Constant background or squeak | Problem with antenna module or shielding | Diagnostics of the fee, soldering |
In the case of hardware breakdown, a module replacement will be required. In the Redmi Note 9, the lower speaker is often assembled with the charging port, which makes it easier to replace, but requires accuracy when disassembling.
Resetting and software update
Sometimes the problem lies in deep system errors after the MIUI update. Accumulated audio driver cache or conflicting application permissions can cause crashes. Try resetting the audio settings: go to Settings → Apps → All Apps, find Settings (or Sound Settings), select Memory and click Clear All.
If that doesn't help, check for system updates. Xiaomi regularly releases bug fixing audio subsystems. Go to Settings → About phone and click on the MIUI version to check for updates.
⚠️ Warning: Hard Reset will remove all information from your phone. Use this method only if other methods have not worked, and make sure to back up.
In extreme cases, if the problem appeared after the update, a rollback to the previous version of the firmware or flashing the device through the computer using the Mi Flash Tool utility can help.