---
title: environmentalSoundReduction
framework: healthkit
role: symbol
role_heading: Type Property
path: healthkit/hkquantitytypeidentifier/environmentalsoundreduction
---

# environmentalSoundReduction

A quantity sample type that measures the difference in sound intensity when wearing headphones that lower environmental sound levels.

## Declaration

```swift
static let environmentalSoundReduction: HKQuantityTypeIdentifier
```

## Discussion

Discussion These samples use sound pressure units (described in HKUnit). They measure discrete values of the equivalent continuous sound pressure level, described in HKQuantityAggregationStyle.discreteEquivalentContinuousLevel. Environmental sound reduction values are automatically collected when wearing supported headphones.

## See Also

### Hearing

- [environmentalAudioExposure](healthkit/hkquantitytypeidentifier/environmentalaudioexposure.md)
- [headphoneAudioExposure](healthkit/hkquantitytypeidentifier/headphoneaudioexposure.md)