Free-Field vs Pressure-Field Microphones: When to Use Which

Understanding the difference between free-field, pressure-field, and random-incidence measurement microphones is essential for accurate acoustic measurement. The choice depends entirely on the acoustic field in which the microphone is used, not on microphone quality or price.

• Free-field microphones: designed for measurement in front of the diaphragm in a plane progressive wave
• Pressure-field microphones: designed for measurement in a uniform pressure field (coupler, IEC 60711)
• Random-incidence microphones: designed for measurement in a diffuse sound field