Signal-to-Noise Ratio

Signal-to-noise ratio (SNR) is the difference in decibels between the peak level of the measurement signal and the steady background noise level. In room acoustic measurements, adequate SNR is critical for reliable reverberation time and clarity parameter extraction. ISO 3382-1:2009 requires a minimum SNR of 35 dB for T20 evaluation and 45 dB for T30 evaluation, with at least 10 dB above these minimums recommended. Insufficient SNR causes the late part of the decay curve to be contaminated by noise, leading to underestimated reverberation times. Swept sine techniques typically achieve the highest SNR (60–80 dB) because the measurement energy is concentrated in a narrow frequency band that sweeps through the spectrum. Improving SNR can be achieved by using a more powerful sound source, averaging multiple measurements, or reducing background noise during the measurement period.