The Microphone boom/Turntable Nor265 may be used as a stand-alone device to obtain the spatial average of sound level by moving a measurement microphone back and forth continuously. Main applications are building acoustic measurements (ISO 140-series), measurement of sound absorption in a reverberation room (ISO 354) and determination of sound power levels of sources using sound pressure (ISO 3741).

Due to the oscillating back and forth movement a normal microphone cable may be fed through the hollow main shaft without the need for slip rings thereby ensuring very low electrical noise levels are maintained. The unit may be equipped with a turntable plate or chuck for mounting of different test objects. In this configuration the main application is measurement of directional responses of acoustic transducers like microphones and loudspeakers.

The unit is manually operated by the rotary switch on the front. As delivered from the factory eight of the switch positions (1, 2… 8) corresponds to ± 90° and ± 180° sweeps with different sweep speeds.

These settings may be redefined by using remote commands if the unit is equipped for remote operation. Extended control of the device is possible by remote commands from a computer by use of the optional serial interface. This allows accurate control of angular position, speed and acceleration.

The unit is robust and constructed for years of maintenance-free operation. When a movement or sweep is started, the speed will gradually increase as specified by the acceleration instruction until the selected speed is obtained. The reversed speed-profile is used for deceleration. By specifying a higher value for the acceleration time, even a large or heavy object may be handled.

Nor265 uses a digital signal processor (DSP) to obtain accurate positioning with simple and robust mechanical design. Accuracy in speed and acceleration are ensured by the use of a precision a crystal clock. The design allows a unique combination of specifications suitable for microphone boom applications as well as a general turntable. The sound emission from the unit is very low, especially when operated at the slower speeds.

Applications

• Building Acoustic measurement in accordance with ISO 140
• Reverberation Time measurements in accordance with ISO 354
• Sound Power measurements in accordance with ISO 3740 series
• Directional response measurements of loudspeakers and microphones

Features

• Sweep of ± 90° (180°) and ± 180° (360°)
• Remote control from a PC
• Accurate positioning
• User defined sweeps
• Selectable sweep times
• Rugged design