4188 1/2-Inch Free Field Microphone
Type 4188 is designed for free-field measurements where an economy microphone with medium sensitivity is required. Being prepolarized, Type 4188 can be used with both CCLD and classical preamplifiers.
- Medium class sound level meters
- Equipment complying with IEC 61672 class 1
- Random-incidence measurements
- Portable sound measuring equipment
- Being prepolarized, Type 4188 is especially well suited for battery-operated equipment or for operation in environments with high humidity.
USE OF FREE-FIELD MICROPHONES
At higher frequencies, reflections and diffraction cause a pressure increase in front of the diaphragm of a microphone. If not corrected for, this would result in an increased output voltage. A free-field optimisation means that the frequency response of the microphone has been designed in such a way that the free-field response at 0 degrees incidence is flat. This microphone is optimised for use with the protection grid in place.
Free-field microphones are commonly used for sound measurement in an anechoic chamber or far away from reflecting buildings, etc. Another area for free-field microphones is for general electroacoustic measurements like loudspeaker and microphone measurements.
Type 4188 is suited for use in IEC 61672 class 1 Sound Level Meters and for general acoustic measurements where a robust and stable free-field microphone with an upper frequency of 12.5 kHz is sufficient. When used with Random Incidence Corrector DZ-9566, Type 4188 can also be used for random-incidence measurements according to ANSI standards.
A press-fitted, stainless-steel diaphragm and a special way of mounting the back-plate make Type 4188 especially robust without sacrificing the excellent long-term stability – Type 4188 will withstand the 1 m drop test of IEC 60068-2-32.
Type 4188 is available in TEDS combinations with either classical or CCLD preamplifier. The TEDS microphone is considered one unit and has been sealed in a clean environment. The TEDS is programmed with the loaded sensitivity of the actual cartridge and the data is therefore readily available. The default TEDS template is according to IEEE P1451.4 but TEDS to IEEE 1451.4 is available on request.
Capacitance: 12 pF
Dynamic range: 15.8 – 146 dB
Frequency range: 8 – 12500 Hz
Inherent noise: 14.2 dB A
Lower limiting frequency -3dB: 5 Hz
Optimised: Free field
Polarization voltages: 0 V
Pressure coefficient: -0.021 dB/kPa
Sensitivity: 31.6 mV/Pa
Temperature coefficient: 0.005 db/ºC
Temperature range: -30 – 125 C
Sound field: Free-field
Input type: Classic
Microphone type: Free field