XL2 Measurement Functions

Sound Level Meter - The Flexible Solution

The XL2 is a powerful sound level meter for events and environmental noise monitoring. Numerous measurement variations are available. Actual level, Lmin, Lmax and Leq may be measured in combination with frequency weighting A, C or Z and time weightings fast, slow and optional impulse. All results are simultaneously available.

XL2 Sound Level Meter

All acquired level information can be automatically written to the removable SD card. The XL2 also offers wav-file recording for a complete documentation of the measured sound pressure levels. Additionally you may add a voice note to each measurement saved.


  • Standards IEC 61672, IEC 60651, IEC 60804, ANSI S1.4, ANSI S1.43

  • Sound levels
    • SPL actual, Lmin, Lmax, Lpeak, Leq, gliding Leq
    • Frequency weighting: A, C, Z (=flat) simultaneously
    • Time weighting: Fast, slow and optional impulse simultaneously
    • Correction values k1, k2
    • Indicators show when sound level limits are exceeded
    • Digital I/O interface for the control of external peripherals
    • Sound Exposure Level LAE (optional)
    • Percentile statistics for Lxy (x= A, C or Z, y= F, S or EQ1"): 1 - 99%  (optional)
    • Calculated levels: LCeq - LAeq, LAIeq - LAeq, LAFT5eq -LAeq (optional)
    • Clock-impulse maximum level "TaktMax" in accordance with DIN 45645-1 (optional)
  • Spectrum Analyzer
    • 1/3 octave, 1/1 octave
    • Frequency weighting: A, C, Z (=flat)
    • Time weighting: Fast, slow and optional impulse
    • Percentile statistics for Lxy (x= A, C or Z, y= F or S ): 1 - 99%  (optional)
  • Logging to SD Card
    • All levels simultaneously
    • Short-time levels including spectrum for 1 second or longer
    • Wav-file for playback (compressed)
    • Data logging in 100 ms intervals (optional)
    • Linear wav-files with 24 bit, 48 kHz resolution (optional)
  • Remote measurement acquisition (optional)

Real Time Analyzer RTA

The RTA perfectly suits tasks such as optimization of sound systems and rooms. The XL2 measures and logs wideband values and the real time spectrum in 1/1 or 1/3 octave band resolution in accordance with IEC 61260 class 0. The sound level meter results of the wide band and RTA spectrum are simultaneously available.

XL2 Sound Level Meter

Acoustic Analyzer

FFT Analysis

The real-time FFT is the ideal tool for visualization of comb filters and narrow band effects. It measures the actual level and the averaged level Leq in three ranges over the entire audio band. The optional Extended Acoustic Pack offers an additional high-resolution Zoom-FFT up to 0.4 Hz steps in the frequency range 5 Hz - 20 kHz. The Spectral Limits Option extends the FFT Analysis with trace capturing, relative curve display and comprehensive tolerance handling.

XL2 FFT Analyzer

RT60 Reverberation Time

The XL2 measures the energy decay in the range from 63 Hz to 8 kHz by the Schroeder method in 1/1 octave bands. Automatic triggering and averaging of multiple measurements simplifies the operation and minimizes the measurement time. Use either an impulse source or an interrupted pink noise as the test signal. The optional Extended Acoustic Pack extends the RT60 measurement to a 1/3 octave resolution.

XL2 RT60 Reverberation Time


For a stereo sound image, it is important to match the polarities of the left and right speakers. The XL2 measures the polarity of cables, single speakers and speaker cabinets. The detailed result page displays the measured polarity as octave bands from 125 Hz to 8 kHz. This allows in-depth verification of the polarity - frequency relation. The polarity test signal is provided by the NTi Audio Test CD or the Minirator test signal generator.

XL2 Polarity

Delay Time

The delay function supports the accurate setup of delay lines and thus the optimization of the directionality of the signal source. The XL2 measures the delay time between the electrical reference signal and the acoustic signal from the speaker. The required delay settings are displayed automatically, allowing the audio engineer to set the measured delay time directly into the delay device in the rack.

XL2 Delay Time

Speech Intelligibility STIPA (optional)

The XL2 Analyzer measures speech intelligibility according to the latest revision of standard IEC 60268-16:2011 (edition 4) as well as older revisions. It offers ambient noise correction and automated averaging for consecutive measurements. The XL2 displays the measurement results as STI or CIS, accompanied by the individual levels and modulation indices of the seven octave bands.

The measurement results are acquired from the dedicated STIPA test signal source:
  • NTi Audio TalkBox
    Acoustic signal generator, required for audio systems that include voice microphones, allows the entire signal chain to be measured.
  • Minirator MR-PRO
    Test signal generator, required for audio systems with line inputs
  • STIPA Test CD

XL2 STI-PA Analyzer

1/12 Octave Band Analysis (optional)

The Spectral Limits Option extends the function range of the XL2 with a 1/6th and 1/12th octave RTA analyzer. The XL2 Analyzer compares spectral measurements against a tolerance band and shows exceptions in every frequency band. This passed/failed condition is further visualized by the limit button and forwarded to the I/O interface of the instrument in order to drive an external alarm device such the accessory Stack Light.

XL2 Sound Level Meter

Noise Curves (optional)

The noise curve measurement provides an objective rating of the background noise level in a room or environment. The noise curve rating of a spectrum is designated as the value of the highest noise curve “touched” by the measured octave-band spectrum. The speech interference level (SIL) and the noise curve rating are calculated in parallel. The Noise Curve function is offered with the Spectral Limits Option.

Supported noise curve measurements and standards:
  • Noise Rating (NR)
    in accordance with ISO 1996
  • Noise Criteria (NC)
    in accordance with ANSI 12.2-2008 and -1995
  • Room Noise Criteria (RNC)
    in accordance with ANSI 12.2-2008
  • Room Criteria (RC)
    in accordance with ANSI 12.2-1995
  • Preferred Noise Criteria (PNC)
    in accordance with ASA 1971

XL2 Noise Curves

Analog Audio Analyzer

Level RMS / THD+N

The XL2 with balanced XLR and unbalanced RCA inputs offers a comprehensive, high performance audio analyzer. It simultaneously measures balance, level, distortion (THD+N) and frequency. The internal loudspeaker or headphone output offers audible monitoring of either the input signal or just the residual distortion. The optimized low distortion and low noise design enable level measurements down to -112 dBu and residual distortions typically lower than -100 dB, which is unmatched in handheld instruments.

XL2 Audio Analyzer

Audio Spectrum

Spectral audio measurements are offered in the units Volt, dBu and dBV within the following measurement functions:
  • Sound Level Meter
  • FFT
  • 1/12 Octave (optional)

XL2 Spectral Audio Measurements


The scope function visualizes the waveform of the electrical input signal. It triggers to the fundamental frequency and selects the scaling of the X-axis (time) and Y-axis (level) automatically. The fundamental or most dominant frequency is displayed above the scope screen.

XL2 Scope

Sound Level Meter
Real Time Analyzer
Audio Analyzer
FFT Spectrum Analyzer
STIPA Analyzer

Contact NTi Audio

NTi Audio Contact Americas  
Brian MacMillan
+1 503 684 7050

Customer Comments

I Love It
“The XL2 is currently the world’s most versatile hand-held acoustic and audio analyser. I can do so much with it, and just love it! And in many ways, the associated Data Explorer software is much more versatile and easier to use than other leading industry equivalents.”
Glenn Leembruggen,
Acoustic Directions
, Australia

Very Simple to Use
"I must say that the instrument and the software are brilliant, and very simple to use, even for an old fogey like me."
Owen Clingan, UK

Better price with more versatility
"I am happy that you keep on developing new applications and uses for the XL2, it is quite a convenient and powerful tool. In my opinion it is a serious competition for the traditional sound level meters at a better price and with more versatility. The Type Approval is an important step forward in the acceptation of the system; even in situations where type approval is not really needed, it helps avoiding discussions on the validity of the measurements."
Ben Kok, www.benkok.com, Netherlands

XL2 Data Explorer Software
"With regards to analyzing the recorded noise data: The idea of hovering over the marker text or locking the set of them is absolutely brilliant for assessing the tonality of a marked section. I could not have thought of a better system. And the percentile calculator letting you choose any marker, filter band or level parameter is just perfect."
Jason Dixon, www.instrulabs.com.au, Australia