NTi Audio

Frequently Asked Questions

Can I perform Class/Type 1 measurements with the Sound Level Meter held in my hand?

Yes, by placing the microphone away from the instrument, thereby ensuring that the sound field to the microphone is not affected by reflections from your body.

Holding the XL2
The correct placement of the microphone

Shielding, Absorption & Reflections

An operator holding any sound level meter in his/her hand, with the microphone connected directly to the instrument, will interfere with the measurement by shielding, absorbing and reflecting the sound. For Class/Type 1 measurements, the microphone must be placed away from such interfering objects and surfaces as these will influence the measured sound levels. For example, the sound level measured 0.5 m from a plane reflecting wall can be up to 3 dB higher than if there is no wall.

Type Approved XL2-TA Configuration

The XL2-TA Sound Level Meter is therefore type approved in the configuration with the M2230 Measurement Microphone detached from the XL2-TA using an ASD Cable. This configuration allows you to perform class 1 measurements by avoiding interference from the instrument housing and the human body standing behind the microphone. The advantage of this configuration is that the operator can monitor the XL2-TA screen whilst performing class/type 1 measurements in accordance with IEC 61672, IEC 61260 and ANSI 1.4, because the microphone is isolated from both the XL2-TA and the operator.

Non-NTi Audio Sound Level Meters

Sound level meters with microphones permanently attached to the instrument create a disadvantage because the instrument itself is required to be placed on a tripod for class 1 measurements in accordance with IEC 61672 and ANSI 1.4. The operator must maintain a minimum safety distance, preventing viewing or operation of the instrument during the measurement.

Basic Measurement

Measurements with less-stringent accuracy requirements can be carried out by simply holding the sound level meter in your hand with the microphone connected directly to the instrument.

Wind & Rain

The measurement has to be performed in dry conditions with a wind speed of less than 5 m/s.


Yes, you can perform Class 1 measurements with the XL2-TA Sound Level Meter held in your hand, by placing the measurement microphone in a mic stand and attaching with the ASD Cable.