ATI NG-1 User Manual

NG-1

AUDIBLE NOISE GENERATOR

OPERATING AND MAINTENANCE MANUAL

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NG-1 AUDIBLE NOISE GENERATOR

Pink Noise is a type of random noise which has equal energy (power) in each octave (2Xf) band of frequencies as contrasted to white noise which has equal energy per Hz. Our ears tend to perceive both pitch and loudness on an octave scale and will recognize sounds of equal energy per octave as having equal loudness. Although an octave centered at 1kHz is 1000Hz and an octave centered on 100Hz is only 100 Hz, our ears integrate the energy equally in these two bands to determine perceived loudness. Pink noise sounds as if it has relatively uniform loudness at all pitches whereas white noise sounds very bright and lacking in low frequencies.

The ATI NG-1 Pink Noise Generator is a useful tool for level matching of multiple microphones in teleconferencing rooms and A/V installations. The NG-1 output is first set to a desired reference level in the range of 60 to 94dB SPL at one foot by ear or using a low cost sound level meter such as a Tandy (Realistic) #33-2050. Multiple microphones can then all be set for equal broadband output by placing the NG-1 in front of each microphone, in turn, on-axis at precisely one foot and adjusting the microphones level control. Gating thresholds for automatic mic mixers can also be set by reducing the NG-1 output by a fixed amount (say 20dBO from the initial reference level using the sound level meter and trimming the hold-in threshold adjustment.

Mid-band room response peaks and valleys can be measured using either a real time analyzer or with a tuned audio voltmeter having octave or 1/3 octave response driven by the output of the sound level meter. Although the internal electronics of the NG-1 provides smooth pink noise response from 20Hz to 20kHz, the small loudspeaker limits the effective acoustical response to a five-octave range from 300Hz to 10kHz. Smooth ten octave pink noise can be supplied to external amplifiers and loudspeakers through the OUTPUT phone jack; inserting a %" phone plug into the output jack disables the internal speaker.

The NG-1 can be AC line or battery powered using the supplied plug-in 9VDC/2OOmA power supply or a 9V alkaline batter mounted inside the case and accessed by removing four rear screws. Remove the battery if the unit will not be used for an extended period to avoid corrosion damage.

The NG-1 incorporates a timer for pulse operation that interrupts the noise output for one second out of every four seconds so that the resulting signal picked up by the microphone can be readily distinguished from background acoustic and electronic noise. Select STEADY or PULSE mode with switch S2.

The NG-1 can provide PINK or WHITE noise by means of the selector switch S3.

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