ST-12D Class 1 Integrating SLM

The IEC 61672-1 Noise Monitoring with 1/1 & 1/3 Octave Band Filters

Overview

ST-12D complies with the Class 1 IEC 61672-1:2013 standard, designed for occupational noise measurement and research. It features a wide measurement range of 25 to 140 dB and is capable of measuring parameters such as Leq, Lpeak, Lmax, Ln, and more. The ST-12D also supports a spectrum analyzer with optional 1/1 and 1/3 octave band filters, enabling real-time frequency analysis for precise noise assessments.
ST-12D Sound Level Meter
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2.4" Vivid Display

2.4" Vivid Display

The full-color display allows for clear measurement readings with a user-friendly interface, intuitive charts, and graphs.

Microphone

Microphone

ST-12D measures noise levels from a detachable 1/2 inch prepolarized condenser microphone with ±0.5 dB accuracy.

Output Interfaces

Output Interfaces

ST-12D includes USB-C, serial, and AC/DC ports, making it easy to connect and integrate with your system.

ScarletSound

ScarletSound

The dedicated PC software for ST-12D user to view noise data, check audio recording and export log file for further report and analysis.

Class 1 Sound Level Meter

Designed for accurate noise measurements in various applications
High precision

High Precision

25 - 140 db wide range compliant with Class 1 IEC 61672-1:2013 standard
Sound Analyzer

Full Capabilties

Integral & statistical calculations, dosimeter, and 1/1 & 1/3 octave band (optional)
Large Storage

Large Storage

Data logging and audio recording in MP3/WAV format with a 64 GB SD card
Parallel Analysis

Parallel Analysis

Measures and displays the Leq value (A/C/Z frequency)

Key Features

Sound Analyzer
Class 1 Performance
Class 1 sound level meter with octave band analysis and audio recording for professional noise measurement needs

Class 1 sound level meter with integral and statistical calculations, and a dosimeter function, ideal for beginners. Enhance your measurement needs with optional 1/1 and 1/3 octave band.

Data Visualization
Full-Color Screen
ST-12D sound level meter displaying noise data on full-color screen with intuitive charts and graphs for easy analysis.

ST-12D makes it easy to read noise measurements through intuitive charts and graphs, enabling quick decision-making and analysis.

Data Management
Via PC Software
Use ScarletSound to view analyze noise data and export log files on a PC

Scarlet developed ScarletSound PC software exclusively for the ST-12D. This software ensures intuitive management of historical records with charts and tables, as well as data exportation.

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Achieve precise noise measurement with ST-12D Class 1 sound level meter.
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Audio Recording

ST-12D offers MP3/WAV audio recording formats with file export capability. Enhance recording efficiency with its trigger mode, activating recording only when sound levels reach a specified limit, effectively optimizing memory usage.

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Audio Recording

Optional 1/1 & 1/3 Octave Band Analysis

Experience precision in sound assestment with the optional 1/1 and 1/3 octave band analysis features for the ST-12D. These upgrades split noise into smaller frequency bands, helping you identify the noise source.

Optional 1/1 & 1/3 Octave Band Analysis

On-the-Go
Waterproof Case

Carry your ST-12D in our durable-design waterproof case, which protects the device and all its accessories, ensuring safe transportation wherever you go.

On-the-Go
Waterproof Case

Frequently Asked Questions

Find quick answers below, or visit our FAQ page for more.

Is training required to use the ST-12D?

No formal training is needed. We provide complete instruction on how to use the device.
ST-12D utilized for traffic noise assessment

Can I extend the microphone away from the main unit?

Yes, microphone extension cables are available in 2.5m and 5m lengths.
Ground crew directing aircraft on runway at airport terminal

Can I connect the ST-12D to external systems or weather stations?

Yes. ST-12D supports analog outputs and RS-232, enabling integration with external systems.
ST-12D with full-color display

Add-Ons

Sound Calibrator

Sound Calibrator

Calibrate your sound level meter periodically to ensure accurate measurements for critical assessments.
Instant Portable Printer

Instant Portable Printer

Print noise data on-site with our portable thermal printer, easily pair with your sound level meter.
Outdoor Kit

Outdoor Kit

All-weather resistance with an anti-perching spike, the outdoor kit ensures obstacle prevention for reliable noise measurements.
It’s now an essential part of our environmental monitoring toolkit.
— Laura Chen
Clear data, easy export, just what we needed.
— George Finn, Plant Manager
Our team had it up and feel satisfied.
— Emily Hart, Construction Site Supervisor

Our Clients

Specifications

  • Performance
  • Design
  • Operation
  • Features
  • Package List
  • FAQ
  • Download
ST-12D Class 1 Sound Level Meter Package List
Item Description
Fulfils standard IEC 61672-1: 2013 Class 1
Main parameters of measurement LXYp, LXYmax, LXYmin, LXeq, LXeq,T, LXeq,t, LXpeak, L5, L10, L50, L90, L95, SD, Ld, Ln, Ldn, SEL, LXE, E, TWA, Lex, 8h, LAVG, DOSE; X = A, C, Z ; Y = F, S, I, I10
Measurement range 25 to 140 dB (143 dB C Peak)
Frequency range 10 Hz ~ 20 kHz
Accuracy ± 0.5 dB
Frequency weighting A, C, Z
Time weighting F, S, I, I10
Integrating time 1s to 99 h 59 m 59 s
Audio recording Record noise data in MP3/WAV format; Synchronize/Trigger mode; Sampling rate: 12 kHz, 24 kHz, 48 kHz / 16 bit, 24 bit
Refresh rate 0.5 s
Item Description
Dimensions 250 × 76 × 33 mm
Weight 340 g
Display 2.4-inch; 240 × 320 pixel full-color display; Adjustable brightness & backlight can be turned off
Display resolution 0.1 dB
Output interface USB type-C, Bluetooth, AC/DC signal, Serial
Item Description
Power supply 4 x AA alkaline batteries; External power supply (USB type-C adapter): 5V, 1A
Operation time Max 24hrs by 4 x AA alkaline batteries (The operation time varies depending on the device settings and battery type)
Operation environment Working temperature: -20 to 60 °C; Relative humidity: 20% to 90%
Storage capacity 4 GB internal memory; 64 GB SD card
Features
▪ IEC 61672-1: 2013 Class 1
▪ Easy-to-use interface
▪ 2.4" full-color display
▪ Synchronous multi sound analyzers
▪ Leq value with A/C/Z frequency weightings
Package List
▪ ST-12D Class 1 sound level meter
▪ Windscreen
▪ USB-C to USB cable
▪ USB power adapter
▪ Serial to RS232 cable
▪ Serial to USB cable
▪ AA batteries
▪ Calibration certificate
▪ User guide
▪ Waterproof carrying case
  • No formal training is needed. ST-12D features an intuitive interface, making it easy to use for professionals and beginners alike.

  • An accurate noise measurement instrument that meets IEC 61672-1:2002 standards (or equivalent standards such as BS EN 61672-1:2003). It has tighter tolerances (+/- 1.9 dB at 1 kHz) compared to Class 2 (+/- 2.2 dB). Class 1 meters are ideal for measuring sound pressure, Leq, and peak sound pressure, often required by regulations like the UK’s Noise at Work.

  • Your choice depends on the application:

    Class 1: Preferred for environmental noise surveys, low noise levels, legal applications, and standards like ISO 20906:2009 for aircraft sound monitoring.
    Class 2: Suitable for less demanding applications without strict accuracy requirements.

  • Conduct field calibrations before and after each use. Additionally, have the device professionally calibrated annually to maintain compliance with standards.

  • Using a windscreen or weatherproof outdoor kit helps reduce wind noise and ensures accurate readings in outdoor settings.

  • Yes, Scarlet offers microphone extension cables (available in 2.5m and 5m lengths) that allow the microphone to be positioned away from the meter, ideal for specific monitoring setups.

  • Yes. ST-12D supports analog outputs and RS-232 serial communication, enabling integration with external systems such as weather stations or environmental monitoring system.

Learn More
Software
  • ScarletSound – Sound Data Management Software for ST-12D and ST-591 (Windows utility)
    2025.07.11
    83.27 MB
  • ScarletSound – Legacy version for ST-12D (Windows utility)
    2025.05.26
    79.71 MB
Datasheet
User Guide

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Fulfils Standard

IEC 61672-1:2013 Class 1 IEC 61672-1:2013 Class 1 IEC 61260-1:2014 Class 1

Accuracy

±0.5 dB ±0.7 dB ±0.7 dB

Measurement Range

27-140 dB 25-140 dB 20-142 dB

Display

240×320 full-color display 128×64 OLED 240×320 color screen

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