Measurement Microphone Placement: Where to Put the Mic

Move a measurement microphone 30 centimeters in any direction and the frequency response can change by 5-10 dB at specific frequencies. Room modes, reflections, and speaker directivity create a complex sound field where the measured response is highly position-dependent. Proper placement ensures that your measurement represents the acoustic conditions that matter for your purpose.

For PA system tuning, the primary measurement position should be at the mix engineer location (typically 60-70 percent of the distance from stage to rear wall). This is where the engineer makes mix decisions, so this is where the system response must be accurate. Place the mic at seated ear height on a stand, at least 1 meter from any surface.

Secondary positions should represent the extremes: front row, rear row, and far sides. These positions show how the system response varies across the audience area. Equalize based on the average of all positions, not the primary position alone.

ISO 3382 specifies measurement positions for room acoustic assessment. Use at least 3 measurement positions for rooms under 300 square meters and 5 or more for larger spaces. Positions should be distributed across the seating area, at least 1 meter apart and at least 1 meter from any surface. Vary the source and receiver positions for each measurement.

When using your phone as a measurement microphone, identify the microphone port location (usually on the bottom edge). Point this toward the sound source. Do not cover the port with your hand. Mount the phone on a tripod or microphone stand adapter for stability and repeatability. If hand-holding is unavoidable, extend your arm to keep your body behind the phone, reducing body reflections that color the measurement above 2 kHz.