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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.

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.

XL2 Sound Level Meter Function


Real Time Analyzer RTA

The RTA perfectly suits tasks such as opti-mization 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.

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 hand-ling.

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 multi-ple 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.


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.

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.

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:

Acoustic signal generator, required for audio systems that include voice microphones, allows the entire signal chain to be measured.

Test signal generator, required for audio systems with line inputs

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.

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.

Level RMS / THD+N

The XL2 with balanced XLR and unbalanced RCA inputs offers a comprehensive, high perfor-mance 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 -100dB, which is unmatched in handheld instru-ments.

Audio Spectrum

Spectral audio measurements are offered in the units Volt, dBu and dBV within the following mea-surement functions:


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.


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