Hi everyone,
Following the update to iOS 27, I have noticed a distinct high-frequency acoustic buzzing/clicking sound coming from the upper-rear portion of my iPhone 16 Pro (near the A18 Pro SoC and power stage).
Issue Details:
- The acoustic artifact triggers directly during rapid UI interactions (fast scrolling, swiping between app cards, Dynamic Island transitions).
- This is not coming from the speakers or haptic engine — it occurs even when all system sounds, audio playback, and haptics are completely turned off.
- It appears to be an acoustic resonance from the PMIC / power delivery components caused by sharp transient voltage changes during brief processor spikes on iOS 27.
Observations:
- Enabling Low Power Mode mitigates the noise by smoothing out processor transients, but disabling ProMotion (120Hz) is not an ideal workaround for daily use.
- Testing alternative power profiles shows that smoother, less aggressive voltage scaling completely eliminates this acoustic noise, confirming it is driven by the iOS 27 power management algorithms rather than a physical hardware defect.
- While iOS 27 offers impressive thermal management, the voltage slew rates during UI rendering appear too aggressive for quiet environments.
Feedback for Engineering: Could the software power management team review the A18 Pro PMIC power lookup tables for upcoming maintenance updates (such as iOS 27.1)? Smoothing the transient voltage scaling slightly during capacitive touch inputs would resolve the acoustic resonance while preserving the thermal benefits of the new system.
If anyone else notices this high-frequency noise in quiet rooms, please click "I have this question too".
