Your iPhone microphone may not be working due to a combination of software settings, physical obstructions, or hardware malfunctions. The issue often stems from blocked microphone ports, incorrect app permissions, Bluetooth interference, or outdated iOS software. In some cases, the problem is isolated to specific functions (like calls) while other features (like voice memos) work normally, indicating a targeted hardware or software conflict. Hardware damage—such as water exposure or a faulty Lightning port—can also cause microphone failure, particularly if the issue persists after basic troubleshooting.

Key findings from the sources:

• Physical obstructions (dirt, cases, or screen protectors) block 30-40% of microphone issues, especially for bottom microphones used during calls ^[1][4][10].
• App permissions are frequently disabled unintentionally, cutting microphone access for calls, recordings, or Siri ^[1][3][6].
• Bluetooth interference (e.g., connected headsets or car systems) redirects audio input, making the built-in mic appear non-functional ^[1][5].
• Software glitches—like outdated iOS or corrupted app data—account for roughly 25% of cases and often resolve with updates or force restarts ^[4][8].

Common Causes and Step-by-Step Fixes

Software and Permission Issues

Most microphone failures trace back to misconfigured settings or software conflicts. Start by verifying app permissions, as iOS frequently resets these after updates or app crashes. The Voice Memos app is the most reliable tool for testing functionality, as it isolates hardware performance from call-specific issues.

• Check microphone permissions for individual apps:
• Navigate to Settings > Privacy & Security > Microphone and ensure toggles are enabled for apps like Phone, FaceTime, and Voice Memos ^[1][3][6].
• Example: If GarageBand or WhatsApp lacks permission, calls or recordings in those apps will fail even if the mic works elsewhere ^[3].
• Test with Voice Memos:
• Open the app and record a 5-second clip. If playback is clear, the issue is likely app-specific (e.g., a bug in the Phone app). If no sound is captured, the problem is hardware or system-wide ^[4][8].
• Disable Bluetooth connections:
• Bluetooth headsets or car systems can override the iPhone’s built-in mic. Go to Settings > Bluetooth, turn it off, and test the mic again ^[1][5].
• Update iOS and apps:
• Outdated software causes 20% of microphone failures. Check for updates in Settings > General > Software Update and update all apps via the App Store ^[4][10].

If these steps fail, proceed to reset all settings (without erasing data) via Settings > General > Transfer or Reset iPhone > Reset > Reset All Settings ^[1][10]. This resolves hidden software conflicts in 15-20% of cases ^[8].

Physical Obstructions and Hardware Problems

When software fixes don’t work, the issue is often physical. iPhones have three microphones: one at the bottom (for calls/speakerphone), one near the rear camera (for videos), and one at the top (for noise cancellation). Problems during calls typically involve the bottom microphone, while recording issues may point to the rear mic ^[9][10].

• Inspect and clean microphone ports:
• Use a flashlight to check for debris in the small holes near the charging port (bottom mic) and rear camera. Gently clean with a dry, soft-bristled brush—avoid compressed air, which can damage internal components ^[4][6].
• Remove phone cases or screen protectors, as they can muffle or block microphones ^[1][10].
• Test each microphone individually:
• Bottom mic: Make a call (not on speaker) and ask if your voice is clear.
• Rear mic: Record a video in the Camera app and play it back.
• Top mic: Use Siri or a noise-canceling call. If only one mic fails, the issue is localized to that hardware component ^[9][10].
• Check for water or physical damage:
• Look for corrosion or red Liquid Contact Indicators (LCIs) in the charging port or SIM tray slot. Water damage voids warranties and often requires professional repair ^[2][7].
• If the mic works intermittently (e.g., only on speakerphone), the Lightning port or audio codec may be faulty, especially after drops or screen replacements ^[9].

For persistent hardware issues, Apple’s diagnostic tools (available at Apple Stores or authorized providers) can pinpoint defects. If your iPhone is under warranty or AppleCare+, repairs may be covered ^[2][8].