Measurement microphone – use, function & tips
What is a measurement microphone?
The measurement microphone is the heart of any room acoustic measurement. It serves as a reference for precisely determining the characteristics of an unknown room. Due to the high demands placed on their transmission characteristics, measurement microphones are almost always condenser pressure transducers. Their power supply requires special power supplies, which typically provide a polarization voltage of 200 volts. Less expensive models use electret condenser capsules, which operate at lower voltages.
Structure and variants of measurement microphones
Measurement microphone capsules are available in four standard diameters: 1 inch, ½ inch, ¼ inch, and ⅛ inch. They are offered in free-field equalized and diffuse-equalized versions. With the appropriate impedance converter, high-quality models achieve linear transmission well into the ultrasonic range. Some models are even capable of recording infrasound.
Typical applications of measurement microphones
Measurement microphones are primarily used in room acoustics optimization, sound reinforcement technology, and research. Typical applications include measuring the frequency response of a room, determining reverberation times, and calibrating loudspeaker systems. A defined sound source such as a sine sweep is usually used for calibration.
Why is choosing the right measurement microphone crucial?
Choosing the right measurement microphone significantly influences the accuracy of your measurements. Professional measurement microphones impress with their extremely linear frequency response and minimal distortion. Especially when optimizing recording studios, home theaters, or concert halls, a calibrated, certified measurement microphone is recommended to obtain reliable and internationally comparable results.
Application of a measurement microphone in practice
In practice, the measurement microphone is positioned at ear level and precisely aligned. Together with acoustic measurement software such as Room EQ Wizard (REW) or ARTA, various points in the room are measured to visualize resonances, room modes, and acoustic weaknesses. Based on this data, targeted acoustic optimization measures such as bass traps, diffusers, or absorbers can be planned.
Measurement microphone as an indispensable tool
A high-quality measurement microphone is key to a thorough analysis of room acoustics. Anyone who wants to create optimal acoustic conditions—whether in a recording studio, home theater, or hi-fi living room—should not forego professional room measurements.
FAQ – Frequently asked questions about measurement microphones
Which measurement microphone is suitable for beginners?
For beginners, inexpensive models like the MiniDSP UMIK-1 or the Behringer ECM8000 are suitable. These microphones offer sufficient accuracy for basic room acoustics analysis and are also easy to connect via USB or XLR.
How do you correctly calibrate a measurement microphone?
Ideally, a measurement microphone is calibrated to a defined sound pressure level using a calibrator. Additionally, software calibration files (e.g., SPL or frequency response calibration) should be used to refine the measurement results.
What is the difference between free-field and diffuse-equalized microphones?
Free-field equalized microphones are designed for direct sound source measurements, while diffuse-equalized microphones are optimized for evenly distributed sound fields (e.g., reverberation measurements). The choice depends on the specific application.
What is a measurement microphone?
A measurement microphone is a specially calibrated microphone for the objective recording of sound. It is used for room acoustics analysis, loudspeaker measurement, and frequency response evaluation, and is characterized by a frequency response that is as linear as possible.
Which microphone should be used for measurement?
A calibrated omnidirectional measuring microphone is used for the calibration. These microphones capture sound as faithfully as possible from all directions and are ideally suited for acoustic measurements.
Where should the measuring microphone be placed?
The measuring microphone is usually placed at ear level at the listening position. For room or loudspeaker measurements, measurements can also be taken at multiple positions to obtain a more realistic overall picture.
Is it possible to record with a measuring microphone?
Technically, this is possible, however, measurement microphones are not optimized for musical recordings. They deliver a very neutral sound without any tone-shaping characteristics and are therefore usually unsuitable for vocals or instruments.