SoundSense

How to measure decibels on iPhone

The iPhone has no built-in meter for the noise in a room. What it measures on its own is the volume of your headphones: add the Hearing control to Control Center and it shows the level in decibels while you listen. To measure the noise around you, use a sound meter app or, if you have one, the Noise app on an Apple Watch.

What the iPhone measures on its own

Headphone level. While you listen through headphones, the Hearing control in Control Center shows how loud the audio is. Apple says the measurement is most accurate with Apple or Beats headphones; with other headphones it is estimated from the iPhone's volume.

  1. Open Settings > Control Center and add the Hearing control (on recent iOS versions you add it by editing Control Center directly).
  2. Play something through your headphones.
  3. Open Control Center: the Hearing control shows the current level.

Your listening history is in the Health app under Hearing > Headphone Audio Levels. To cap the volume, go to Settings > Sounds & Haptics > Headphone Safety and turn on Reduce Loud Audio: the iPhone then turns down any headphone audio above the level you set. Menu names change between iOS versions, so check Apple's guide for yours if a step looks different.

Room noise with an Apple Watch. The Noise app on Apple Watch measures the sound around you with the watch's microphone and can tap your wrist when the level stays high enough to affect your hearing. Apple says it does not record or save any sounds. The history appears on the iPhone in Health > Hearing > Environmental Sound Levels.

Measuring room noise with an iPhone app

  1. Install a sound meter app from the App Store and allow microphone access. A sound meter needs nothing else.
  2. Find the microphone. The main microphone is on the bottom edge of the iPhone, next to the charging port. Keep your fingers and a thick case away from it.
  3. Hold the phone still at arm's length, away from your body, with the bottom edge facing the sound.
  4. Measure for at least 30 seconds, or several minutes for noise that comes and goes.
  5. Read the average (LAeq) in dBA. Health limits and most complaint procedures use the average, not the loudest moment.
  6. Measure the quiet too, so you have a background level to compare against.

The same tips as on any phone apply: keep the microphone out of the wind, don't touch the phone while it measures, and measure from the same spot each time if you want to compare. Our Android guide covers them in more detail.

How accurate is an iPhone?

Good enough for a useful estimate. NIOSH, the US workplace health institute, built its free NIOSH SLM app for iPhone and rates it accurate within ±2 dBA in its laboratory; with a calibrated external microphone it meets the Type 2 requirements of the IEC 61672 sound level meter standard. NIOSH says it cannot verify Android apps the same way because Android hardware varies so much.

A phone reading is still an estimate. Microphones and their processing are designed for speech, and very loud sound can overload them. For legal, workplace or medical decisions, use a certified sound level meter.

SoundSense on iPhone

SoundSense, the decibel meter we make, is on Android today and coming to the App Store. On Android it shows the level in dBA with a 60-second live graph, saves each check with a title, place and notes, and reports the average (LAeq), minimum, maximum and time above a threshold you choose. No audio is ever recorded or uploaded.

Sources

Updated by the SoundSense team at Just IT.