Intensity Microphone Kit 1/2″ GRAS 40GK

Introduction

• The 40GK is an IEC 61043-compliant ½” prepolarized sound-intensity microphone pair. Read about the externally polarized equivalent [40AK].
• The microphones in the kitt are two 40GI microphones – two phase-matched free-field measurement microphones with extremely well-controlled phase characteristics for use in sound-intensity probes. This microphone pair has a free-field frequency response that complies with IEC 61043 1993 Class 1 and IEC 60651 Type 1 in the range from 20 Hz to 10 kHz.
• The 40GK kit also includes solid spacers for 12 mm, 25 mm, 50 mm, and 100 mm intensity-probe configurations, as well as adapters for the 26CB ¼” CCP preamplifier set. The 40GK is included in the GRAS 50GI CCP Sound Intensity Probe.
• 40GK is individually factory-calibrated and delivered with a calibration chart, stating its specific open-circuit sensitivity and pressure frequency response.

Typical applications and use

• The 40GI is designed for sound-intensity and sound-power measurements, as well as sound-source localization, which is why it is included in the 50GI probe in the 40GK kit. Each 40GI microphone pair is phase matched according to the phase specifications for a Class 1 Sound Intensity Probe in accordance with international IEC 61043, Electroacoustics – Instruments for the Measurement of Sound Intensity – Measurements with Pairs of Pressure Sensing Microphones, 1993.
• The quality of a sound intensity probe microphone is its ability to measure the real part of a complex sound intensity in highly reactive sound fields as well as in sound fields exposed to high levels of background noise. This ability depends largely on the phase responses of the microphone pair. The individual phase matching of each 40GI ensures that any differences in phase responses are extremely small.
• The 40GI is also used for ranking of sound sources. When mounted in the 50GI sound-intensity probe, the microphones can pinpoint the area generating the most noise, which may then require additional measurements, depending on the measurement procedures and processes used. The sound-intensity microphones reveal the weak and strong points when identifying noise sources. Sound-source ranking is useful as long as the background noise doesn’t exceed the noise source.

Compatibility

• The 40GK includes straight and right-angled adapters for ¼” CCP preamplifiers, which requires an input module that supports this technology with a BNC or Microdot connector.
• In the 50GI Sound-Intensity Probe, the 40GK pair is combined with the 26CB ¼” CCP preamplifier set.