What is the noise coming from my M4 MacBook Air keyboard?

1. Thermal Expansion in the Keyboard Area

The M4 MacBook Air, like most laptops, uses thermal pads and heat dissipation methods to keep things cool. If the keyboard area is where the heat is most concentrated, thermal expansion of the internal components (like the logic board or heat transfer materials) could cause a slight "hissing" or soft pressure noise as the materials shift or expand due to temperature changes.

• Does the sound change after using the laptop for a while or when it heats up (e.g., after charging, running heavy apps, or video streaming)? If it’s more noticeable when the laptop is getting hot, this is likely thermal-related.

2. Keyboard or Trackpad Mechanism

Another possibility is the keyboard's butterfly mechanism or the internal trackpad. While newer MacBooks (including the M4 Air) use scissor switches, there could still be very small, subtle sounds coming from the mechanisms inside the keys as they press and release. If something is out of alignment or if there’s any dust/debris trapped under the keys, it could cause the keys to produce a soft noise.

• If the sound seems tied to specific keys or areas of the keyboard, it could just be mechanical noise from the key switches. You can try gently pressing around the keyboard to see if it makes a difference.

3. Electrical Interference or Power Supply

Another possibility is electrical interference near the keyboard area. The power components (like the power IC or motherboard) are located under the keyboard, and sometimes electrical issues, like coil whine, can cause a faint hissing sound that seems localised to the keyboard.

• Is the noise more noticeable when charging or when the MacBook is under load? If it's linked to power demand, this could be electrical noise coming from the internal circuits.

4. Speaker or Audio Driver Issue (Rare, But Possible)

If you hear the hissing when playing sound or even without audio playing, it could also be a result of audio driver interference. It’s not common, but sometimes electrical noise or interference in the motherboard can travel to the speakers and cause soft buzzing or hissing, which can seem localised to the keyboard area.

I asked Chatgpt about your issue, and this is what I found out. Try check if your laptop is overheating using the Hot app. If not overheating try playing some audio from your device and keep watch of the hzzzzzing sound.Now mute your device and see if the hzzzzzing sound is gone. If not then send your device to Apple for their diagnosis.

Also I own a MacBook Air m4 13 inch but I do not face this problem so I do not have experience with it.