Environmental Noise Measurement

Environmental Noise Monitoring

The Sound Level Meter provides the dedicated solution for environmental noise monitoring in industry and communities. It measures levels and detailed spectral information in parallel and stores the data on an SD card for post-processing and reporting. A linear audio file (wav-file) may be recorded for detailed simultaneous analysis.

At a glance

  • Noise annoyance assessment
  • Rating level calculation
  • Verifying boundary noise level emission


The XL3 is a class 1 sound level meter and offers a flexible handheld instrument with accurate and reliable measurements. Data recording can be scheduled to occur at pre-determined times or automatically triggered when pre-determined levels are exceeded. The Data Explorer software automatically marks periods containing tones or impulse and calculates the rating level Lr for comparison with the applicable limits.

Measurement Functions

XL2 with M4260 Measurement Microphone

Sound Level Meter

Sound Pressure Level SPL

The Sound Level Meter monitors the noise pollution to verify any annoying or excessive noise. All sound levels such as actual, Lmin, Lmax, Leq and the sound exposure level LAE are simultaneously measured and logged with frequency weighting A, C, Z and time weightings Fast, Slow and the optional Impulse.

The event recorder functionality triggers the measurement by programmable level thresholds or manually by the external input key pad. (optional with Extended Acoustic Pack).

Rating Level Lr

The Sound Level Meter measures environmental noise according to the ISO 1996 standard. The Rating Level Lr is used as a measure to evaluate long-term annoyance of noise. This is calculated from the A-weighted equivalent continuous sound level LAeq with various adjustments:

Lr = LAeq + KI + KT + KR + KS
KI Adjustment for impulsiveness
KT Adjustment for tones and information content (survey and engineering method)
KR Adjustment for the time of the day
KS Adjustment for special situations and noise sources

These adjustments are standardized and differ between countries. The Data Explorer software automatically determines periods with impulsive or tonal noise and calculates the rating level Lr. 

Percentiles (optional)

Measures statistic sound levels in wideband and the real time spectrum 0,1% - 99,9%.

Application Examples:
  • Road Traffic Noise
  • Industrial Noise
  • Noise Pollution Level LNP = Leq + (L10 - L90)

Remote Measurement (optional)

Allows querying the measurement data online via the USB interface. Thus customers may integrate the XL3 into their noise monitoring application.

Outdoor Measurement Microphone

Outdoor Measurement Microphone

The Outdoor Measurement Microphones offer a weather-protected measurement solution for the Sound Level Meter allowing acquisition of environmental noise data in outdoor applications. The corrosion-free polymer housing, wind screen, waterrepellent membrane and bird spike provide excellent protection from rain, wind, dust and perching birds.

The Outdoor Measurement Microphones M2230-WP and M2340-WP fulfill the Class 1 requirements according to IEC 61672 and ANSI S1.4 for horizontal and vertical sound incidence. For compliance with horizontal sound incidence a spectral correction is employed in the associated Sound Level Meter. The Outdoor Measurement Microphone M4261-WP fulfills the Class 2 requirements accordingly.

The outdoor microphones consist of a measurement microphone and the applicable weather protection:

  • M2230-WP: M2230 + WP30-90/ -150 Weather Protection
  • M2340-WP: M2340 + WP30-90/ -150 Weather Protection
  • M4261-WP: M4261 + WP61 Weather Protection


  • Class 1 and Class 2 Outdoor Measurement Microphones for horizontal and vertical sound incidence according IEC 61672 and ANSI S1.4
  • Excellent protection from rain and dust (IP54), wind and perching birds
  • Built from corrosion-free materials
  • Removable top section for easy microphone calibration
  • Standard tripod mount, optional pole mount

Effective outdoor protection

The 90 mm or 150 mm wind screen protects the measurement microphone from rain and dust while reducing wind-induced noise. The seamless design of the water-repellent membrane under the wind screen ensures perfect protection from rain and dust.

System self-test 

The Outdoor Measurement Microphone M2340-WP is system self-test (CIC) enabled. Automated self-tests may be performed by NoiseScout, the unattended noise monitoring solution, in combination with the Sound Level Meter. This ensures reliable operation and precise measurements.

Robust design / Easy calibration

The upper section of the weather protection is snap-on mounted and can thus be easily removed by hand for manual calibration of the measurement microphone.

Basic Outdoor Case

Basic Outdoor Case
The Basic Outdoor Case is a simple and efficient solution for outdoor noise monitoring. Powered either by an external mains supply or a small, high capacity battery pack the case is more than adequate for a number of days of monitoring. The robust and lightweight design protects the Sound Level Meter and accessories from a wide range of inclement weather conditions.

NTi Audio #:
  • IP43: 600 000 471
  • IP63: 600 000 473

Heavy Duty Outdoor Case

XL2 Outdoor Case

The heavy duty outdoor case is a professional solution for short- and medium term unattended noise monitoring. The case provides comprehensive protection against dust, water and impacts. Internal dimensions provide ample space for battery packs to power the Sound Level Meter.

NTi Audio #:

  • IP43: 600 000 476
  • IP65: 600 000 477
Product Data

Noise Monitoring Terminal

Noise Monitoring Terminal

The weatherproof enclosure is the tailored fixed installation solution for unattended noise monitoring. The enclosure is IP66 (without ventilation) or IP55 (with built-in fan) rated, highly secure and constructed of strong, hard-wearing reinforced fiberglass.

NTi Audio #:

  • Enclosure Large, IP55: 600 000 480
  • Enclosure Large, IP66: 600 000 486
  • Enclosure Compact, IP66: 600 000 485

Product Data

Type Approval Option

The Type Approval Option, when installed on your XL2, upgrades the instrument to the XL2-TA, the sound level meter for certified measurements. The XL2-TA, together with the M2230 or M2340 microphone and Shroud jacket, forms a type-approved sound level meter offering class 1 performance in accordance with IEC 61672:2014, IEC 61260:2014, ANSI S1.4:2014 and ANSI S1.11:2014 standard. The Type Approval Option includes the Shroud MXA01.

Type approved sound level meter configuration:

  • XL2-TA Sound Level Meter (XL2 with Type Approval Option installed)
    • Measurement Microphone M2230 or M2340
    • Shroud MXA01
    • Firmware V4.71 (AT, CH, DE)
    • Firmware V4.21 (FR)
  • NTi Audio Class 1 Sound Calibrator
  • Optional
    • Extended Acoustic Pack
    • ASD Cable 5 m, 10 m or 20 m
    • Mains Power Adapter
    • Wind Screen 50 mm or 90 mm
    • Weather Protection WP30
    • XL2 Input Keypad
    • Microphone Holder MH01


XL2 Type Approval Certificates:

Local Noise Monitoring Network

Multiple XL2 Analyzers connect with USB Device Servers via LAN or Wi-Fi within a local network for online noise monitoring. An individual Projector Software may be started for each XL2 Analyzer, thus simultaneously displaying all XL2 screens on the PC monitor. Each XL2 Analyzer can be controlled from the host PC.

XL2 Noise Monitoring Network

Individual Solution programmed by Customer

The Remote Measurement Option allows querying of the XL2 measurement data online via the USB interface. Multiple XL2 Analyzers can be implemented into a customer specific noise monitoring solution. The XL2 acts as a front end device for sound level measurements.

News Articles about Noise Measurement


Exel Set for Environmental Noise Monitoring

XL2 Kit for Environmental Noise Monitoring

  • XL2 Sound Level Meter
  • Extended Acoustic Pack for XL2
  • Data Explorer 365
  • M2230 Measurement Microphone
  • ASD Cable for XL2
  • Mains Power Adapter
  • Exel System Case

Optional as required:

Weather Protection WP30

for outdoor noise assessments

Type Approval Option for XL2

for type approved measurements and certification

Sound Calibrator

for accurate noise measurements

Remote Measurement Option for XL2

for querying measurement data online from the PC

Stack Light

for visual (pre-) warning indication

Get more Information

Contact us for a quotation or to discuss your measurement application.

Request Quotation    Call now: +1 (503) 684-7050