1,20 s
0.0 s (Ideal Dirac) 1.2 s (Room) 2.5 s (Hall)
-50 dB
-65 dB (Quiet) -35 dB (HVAC) -12 dB (Extreme)
3. Regression Lines & Evaluation
4. Chirp Duration (Time Doubling = +6 dB SNR):
+18 dB SNR (4 s)
True RT60
1,20 s
Measured T20 (-5..-25 dB)
1,20 s
Measured T30 (-5..-35 dB)
1,20 s
Effective SNR
50 dB
WINDOW 1 • TIME DOMAIN (OSCILLOSCOPE)
Room Impulse Response h(t) + Background Noise
Decay Tail
At RT60 = 0.0 s you hear and see the ideal anechoic Dirac delta impulse. As you increase the reverberation time, the impulse expands into a decaying pink-noise reverberation tail.
WINDOW 2 • SCHROEDER INTEGRATION (LEVEL IN dB)
Integrated Impulse Response & T20 / T30 Regression
As soon as background noise enters the evaluation range (-5 to -25 dB or -35 dB), the Schroeder curve bends upward—the measurement becomes systematically falsified or fails.
INTERRUPTED PINK NOISE METHOD (DIN EN ISO 3382)
Excitation Plateau, Cutoff (t = 0) & Reverberation Decay Tail with Noise Floor
Left (-0.8 s to 0.0 s): Stationary pink noise excites the room until an energetic steady-state plateau (0 dB) is reached.
Center (After Cutoff t = 0.0 s): After switching off the source, the sound field in the room decays according to the selected reverberation time RT60.
Background Noise Effect: Superimposed background noise (e.g. HVAC at 125 Hz) raises the noise floor and directly falsifies the T20 / T30 regression lines.
WINDOW 1 • IN-ROOM MICROPHONE SIGNAL