Limit Maximum Volume to Prevent Speaker Diaphragm Distortion

Since the crackling is caused by the speaker hardware reaching its physical mechanical threshold at high volumes, you must restrict the audio output to prevent reaching that limit.

1. Open the Settings app on your iPhone 15.
2. Scroll down and tap on Sounds & Haptics.
3. Select Headphone Safety.
4. Toggle on Reduce Loud Sounds.
5. Adjust the decibel slider to 75 decibels or lower.
6. Verify the fix by playing the same audio content that previously caused the crackling while the volume is set to maximum; the sound should no longer exhibit distortion as the system now prevents the speaker from driving the diaphragm beyond its mechanical limit.

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