The exported points are resampled onto a 48-points-per-octave logarithmic grid and smoothed by power-averaging over ±1/24 octave (the 1/12-octave curve) and ±1/6 octave (the 1/3-octave curve), the same convention REW uses. The reference level is the average of the 1/3-octave curve from 200 Hz to 10 kHz; flatness is the largest excursion from it in that band. Bass extension is read downward from 200 Hz on the 1/3-octave curve (−3 dB and −10 dB). Modal peaks and dips are the 1/12-octave curve against a two-octave trend below 300 Hz (+6 dB and −8 dB, a rule of thumb). The treble slope is a least-squares fit of the 1/3-octave curve from 1 kHz to 10 kHz in dB per octave.
Impulse responses: the energy-time curve is 20 log of the sample magnitude relative to the peak; the decay is Schroeder backward integration of the squared response, and EDT, T20 and T30 are the 0 to −10, −5 to −25 and −5 to −35 dB fits of it (ISO 3382), broadband. The magnitude response is an FFT of 500 ms from the peak with a Hann tail; its absolute level is unknown, so it is drawn around 75 dB.
RT60 tables: the mid-band figure averages the 500 Hz to 1.25 kHz bands and is compared with CEDIA/CTA-RP22's 0.2–0.5 s recommendation for home cinemas; the bass ratio divides the bands below 250 Hz by it.
Thresholds marked "rule of thumb" or "common practice" are exactly that. The named standards are ISO 3382 (decay definitions), CEDIA/CTA-RP22 (home cinema reverberation), the Dolby and DTS LFE bandwidth, and the Harman in-room target research; the SMPTE X-curve is mentioned as the large-room reference. Nothing here replaces a calibrator's judgement or REW's own analysis tools. Files stay in your browser.
