LMS partners with G.R.A.S. to offer a large range of high quality measurement microphones for industrial acoustics applications.
TEDS microphones
TEDS measurement microphones are combined sets consisting of high-precision condenser microphones and preamplifiers. TEDS is a standardized technology that enables the microphone to be recognized by any smart-transducer compatible input module. When connected, the analyzer will derive information like type, serial number and sensitivity, which will be read by the application software.
Various applications
The microphones are designed according to IEC 61094, Class 1, and thus fulfilling the highest standards for reliability and precision. All G.R.A.S. microphones and pre-amplifiers are made of stainless steel to ensure long life and high protection in use. The microphone unit has a 5 year warranty against defective materials and workman-ship. Should a microphone unit be damaged, it is specially designed to be repaired. G.R.A.S. offers repair and calibration services through local distributors.
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Intensity measurement is a practical tool for locating and ranking sound sources and determining the emitted sound power. The method is based on the simultaneous determination of sound pressure and particle velocity using two closely spaced, face-to-face measurement microphones. The probe is also named a pressure-pressure probe and is especially designed to measure the sound intensity of complicated sound sources as well as to minimize the influence of the sound field.
The probe is equipped with two ½” pre-polarized intensity microphones which meet the requirements of the IEC 61043 standard for a Class 1 intensity probe and are carefully phase-matched to ensure maximum measurement accuracy. Together with the two CCP preamplifiers the probe is directly compatible with LMS’ 4 mA ICP® input modules.
The frequency range is determined by the distance between the two intensity micro-phones. The probe comes with a selection of spacers that enables diagnostics from 50 Hz to 10 kHz. These spacers are easily interchanged without having to dismantle the probe.
The Intensity Probe Type 50AI-L is a dedicated LMS probe with built-in USB-remote control. Its well-known, four-button interface allows for single-handed operation of the application software and gives the opportunity to keep focus on the object being measured.
TEDS measurement microphones are combined sets consisting of high-precision condenser microphones and preamplifiers. TEDS is a standardized technology that enables the microphone to be recognized by any smart-transducer compatible input module. When connected, the analyzer will derive information like type, serial number and sensitivity, which will be read by the application software.Various applications
| Application | 46AE | 46BE | 46AQ | 46BD |
| Pass-by | ■ | ■ | ||
| Sound Power | ■ | |||
| Array | ■ | ■ | ||
| In-room Material Testing | ■ | |||
| Exhaust Noise | ■ | |||
| Impulse Measurements (air-bag testing) | ■ | |||
| Interior Noise | ■ | |||
| Transmission Loss | ■ | |||
| In-tube Material Testing | ■ | |||
| Plate Array | ■ |
The TEDS measurement microphones are available with different properties and in the scheme are listed typical applications and their corresponding microphone types. The shown types are all pre-polarized and compatible with LMS’ 4 mA ICP® input modules. For other applications, including outdoor microphones or low noise systems please contact us.
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Reliability
The microphones are designed according to IEC 61094, Class 1, and thus fulfilling the highest standards for reliability and precision. All G.R.A.S. microphones and pre-amplifiers are made of stainless steel to ensure long life and high protection in use. The microphone unit has a 5 year warranty against defective materials and workman-ship. Should a microphone unit be damaged, it is specially designed to be repaired. G.R.A.S. offers repair and calibration services through local distributors.
| Type | Size | Application | Normal Sensitivity | Frequency Range | Dynamic Range | Temp. Rnge |
| 46AE | 1/2” | Free-field | 50 mV / Pa | 3.15 Hz - 20 kHz | 14 dBA - 135 dB | -30° C to +70° C |
| 46BE | 1/4” | Free-field | 4 mV / Pa | 4 Hz - 80 kHz | 30 dBA - 160 dB | -30° C to +70° C |
| 46AQ | 1/2” | Diffuse-field | 50 mV / Pa | 3.15 Hz - 12.5 kHz | 14 dBA - 135 dB | -30° C to +70° C |
| 46BD | 1/4” | Pressure-field | 1.6 mV / Pa | 4 Hz - 70 kHz | 38 dBA - 168 dB | -30° C to +70° C |
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Technique and applications
Intensity measurement is a practical tool for locating and ranking sound sources and determining the emitted sound power. The method is based on the simultaneous determination of sound pressure and particle velocity using two closely spaced, face-to-face measurement microphones. The probe is also named a pressure-pressure probe and is especially designed to measure the sound intensity of complicated sound sources as well as to minimize the influence of the sound field.Sound intensity probe with pre-polarized microphones
The probe is equipped with two ½” pre-polarized intensity microphones which meet the requirements of the IEC 61043 standard for a Class 1 intensity probe and are carefully phase-matched to ensure maximum measurement accuracy. Together with the two CCP preamplifiers the probe is directly compatible with LMS’ 4 mA ICP® input modules.
Variable frequency range
The frequency range is determined by the distance between the two intensity micro-phones. The probe comes with a selection of spacers that enables diagnostics from 50 Hz to 10 kHz. These spacers are easily interchanged without having to dismantle the probe.
Dedicated remote control
The Intensity Probe Type 50AI-L is a dedicated LMS probe with built-in USB-remote control. Its well-known, four-button interface allows for single-handed operation of the application software and gives the opportunity to keep focus on the object being measured.
| Type | Application | Normal Sensitivity | Frequency Range | Dynamic Range | Temp. Range |
| 50AI-L | Sound Intensity | 12.5 mV / Pa | 20 Hz - 10 kHz | 20 dBA - 160 dB | -30° C to +50° C |
Technique and applications
For advanced sound source location in the near- and far-field we offer a range of array microphones for acoustic beam-forming, acoustic holography and focalization.
Three microphone types
Depending on the required precision, resolution and amount of channels three micro-phone types are available;
- Array microphone for large-scale multi-channel systems (Type 40PH). This type can be mounted in standard or custom made array structures.
- Traditional ¼” measurement microphone for high-precision, scientific arrays (Type 46BE). This type can be mounted in standard or custom made array structures.
- Surface microphone (Type 40PS) for making measurements on planar and curved surfaces It is especially suitable for testing in wind tunnels and for testing in confined spaces with little or no space for traditional array solutions. Its water-repellent microphone protection grid makes it robust and the flat design enables boundary layer measurements without having to destroy or change the object’s shape and properties.
All three microphone types are smart transducers with built-in TEDS that enables the application software to identify and set up the required signal conditioning as well as to position the microphone in any given array structure. They are all pre-polarized microphones and compatible with LMS’ 4 mA ICP® input modules.
ArraysThe actual shape and size of a microphone array is given by the application, the number of available input channels, the required resolution and frequency range. G.R.A.S. has a variety of standard array modules available, all optimized to reduce the disturbance of the acoustic field of interest. These modules are scalable and allows for both fixed and individual spacing of the array microphones in order to meet the requirements for definition, frequency range and application.
| Type | Application | Normal Sensitivity | Frequency Range | Dynamic Range | Temp. Range |
| 46BE | High-precision arrays | 4 mV / Pa | 4 Hz - 80 kHz | 30 dBA - 160 dB | -30° C to +70° C |
| 40PH | Large-scale arrays | 50 mV / Pa | 10 Hz - 20 kHz | 32 dBA - 135 dB | -10° C to +50° C |
| 40PS | Surface arrays | 5 mV / Pa | 100 Hz - 20 kHz | 30 dBA - 136 dB | -20° C to +80° C |
In order to maintain the highest possible data quality you will typically – before you start a measurement session – verify that your measurement chain is working according to specifications. For that purpose we offer a sound calibrator for calibrating the measurement microphones. This reference sound source generates a 1 kHz tone at 114 dB corresponding to 10 Pascal and accommodates for all the TEDS microphones described above. We also offer a sound calibrator for calibrating the sensitivity of the intensity microphones.
For verification of the phase matched response we recommend to use the dedicated Intensity Calibrator Type 51AB. It complies with IEC 61043 and includes a calibrated acoustic resistance also enabling calculation of particle velocity and intensity levels.
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