---
title: PHASEGeometricSpreadingDistanceModelParameters
framework: phase
role: symbol
role_heading: Class
path: phase/phasegeometricspreadingdistancemodelparameters
---

# PHASEGeometricSpreadingDistanceModelParameters

An object that dissipates sound frequencies over distance.

## Declaration

```swift
class PHASEGeometricSpreadingDistanceModelParameters
```

## Mentioned in

Playing sound from a location in a 3D scene

## Overview

Overview This class implements a roll-off effect — a strategy that aims to model the real-world manner in which sound changes with distance. When the distance between a sound and listener changes, the roll-off effect dissipates certain audio frequencies more than others. Dissipate Sound by Choosing a Roll-Off Factor PHASE emphasizes or deemphasizes the volume loss of the mixer’s sound sources based on the rolloffFactor you choose. For example, a rolloffFactor of 1.0 reduces sound between the source and listener by 6 dB for every doubling of distance. At 2.0, the loss doubles. At 0.5, the loss halves. To add a geometric-spreading distance model to a spatial sounds, set the mixer’s distanceModelParameters property to an instance of this class. For example:

## Topics

### Creating the Distance Model Parameters

- [init()](phase/phasegeometricspreadingdistancemodelparameters/init().md)

### Setting the Roll-Off Factor

- [rolloffFactor](phase/phasegeometricspreadingdistancemodelparameters/rollofffactor.md)

## Relationships

### Inherits From

- [PHASEDistanceModelParameters](phase/phasedistancemodelparameters.md)

### Conforms To

- [CVarArg](swift/cvararg.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [NSObjectProtocol](objectivec/nsobjectprotocol.md)

## See Also

### Distance Modeling

- [PHASEEnvelopeDistanceModelParameters](phase/phaseenvelopedistancemodelparameters.md)
- [PHASEDistanceModelFadeOutParameters](phase/phasedistancemodelfadeoutparameters.md)
- [PHASEDistanceModelParameters](phase/phasedistancemodelparameters.md)