Poor Measurement Quality

Understanding Quality Metrics

Signal-to-Noise Ratio (SNR)

SNR measures how much louder the test signal is compared to background noise. Higher is better.

40+ dB: Excellent—accurate measurements
30-40 dB: Good—usable for most purposes
20-30 dB: Marginal—may have issues at frequency extremes
<20 dB: Poor—retake recommended

Coherence

Coherence indicates how consistent the measurement is. A value of 1.0 means perfect consistency; lower values indicate noise or nonlinear distortion.

>0.9: Excellent
0.7-0.9: Good
<0.7: Questionable—investigate noise sources

Common Causes and Solutions

Cause: Test signal too quiet

Solution: Increase speaker volume. The measurement signal should be:

Clearly audible throughout the room
About 70-80 dB SPL at the listening position
Louder than any background noise

Protect Your Hearing

Don't make the test signal uncomfortably loud. 75-80 dB is adequate—you shouldn't need hearing protection for measurement.

Cause: High background noise

Solutions:

Turn off HVAC/fans/refrigerators during measurement
Close windows and doors
Measure at a quiet time (not during traffic rush)
Ask family members to stay quiet and still
Put pets in another room

Cause: Microphone gain too low

Solutions:

Check audio interface gain if using XLR mic
For USB mics, gain is usually automatic—verify in Settings
Test with the monitoring feature before measuring

Optimal Measurement Environment

Ideal Conditions Checklist

✓HVAC/fans off (or at minimum setting)
✓Windows and doors closed
✓No other people or pets in room
✓Measurement at night or quiet time of day
✓Test signal at 70-80 dB SPL
✓Microphone on stable stand (not handheld)
✓Complete stillness during 30-second sweep

When Good Enough is Good Enough

Don't obsess over perfect measurements. An SNR of 35 dB is perfectly usable. Small amounts of noise at 18 kHz don't matter much for room correction. Focus on getting good bass and midrange data.