# Dual SPL Traffic Light — Monitor live Sound Levels

> Monitor live Sound Levels (iPhone/iPad app by Andrew Smith.)

- Source: https://appshunter.io/ios/app/dual-spl-traffic-light/id1088001201 (this page in markdown: same URL + `.md`)
- Developer: [Andrew Smith](https://appshunter.io/developer/291822462)
- Category: Music, Utilities
- Price: $19.99
- Age rating: 4+
- Requires: iOS 13.0 · 29 MB
- Languages: American English, French (France), German (Germany), Japanese, Polish, Chinese (Simplified, China), European Spanish, Swedish, Chinese (Traditional, Taiwan)
- Released: 2016-03-09
- Data updated: 2026-08-14
- User reviews in markdown: https://appshunter.io/ios/app/dual-spl-traffic-light/id1088001201/reviews.md

## What is Dual SPL Traffic Light?

Dual SPL Traffic Light

Monitor sound levels for events, public spaces, and concerts. Two independent sound monitors allow you to configure this app to any local requirements.

For example, set one traffic light to average SPL over 10 minutes, and set the other to monitor peak levels.

Set one to A weighting, and the other to C weighting, or flat.

This app works fine with the internal iOS device mic. You can also upgrade to our iPrecisionMic or iTestMic to get Class 1 or Class 2 results. 

Each traffic light can be linked to a color light bulb using HomeKit, to provide visible notification of sound levels. Place a color light bulb near the sound mixer, stage, or even the manager's office, so that everyone can see if the sound levels exceed your preset trigger levels.

Set the SPL decay (speed and type of averaging) to Fast, Slow, or any Leq value from 1 second to 8 hours. The Leq can be done one time period at a time, or it can be a running Leq of the last time period.

Set the SPL weighting to flat (Z), A, C, or one of the low frequency octave bands, 32Hz, 63Hz, 125Hz, or 32Hz+63Hz.

Includes email notifications for sending emails when either or both meters is triggered into the red level.


## Version history (last 5 releases)

### 3.8 — 2026-06-02

-Accessory Connect message disappears on its own
-Lots of bug fixes and stability improvements

### 3.7 — 2025-12-22

-Bug fixes and stability improvements

### 3.6 — 2025-11-24

-Updated for new iOS devices
-Bug fixes and stability improvements

### 3.5 — 2024-11-20

-Updated for latest iOS devices and calibrations
-Bug fixes and operational improvements

### 3.4 — 2024-07-10

-Updated for latest iOS devices and calibrations
-Bug fixes and operational improvements

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## More apps by Andrew Smith

- [Speaker Polarity](https://appshunter.io/ios/app/speaker-polarity/id293263027)
- [SPL](https://appshunter.io/ios/app/spl/id293573990)
- [RTA](https://appshunter.io/ios/app/rta/id298839433)
- [FFT](https://appshunter.io/ios/app/fft/id298840058)
- [RT60](https://appshunter.io/ios/app/rt60/id298840320)
- [Generator](https://appshunter.io/ios/app/generator/id298840802)

All apps by Andrew Smith: https://appshunter.io/developer/291822462

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-14.*