Genelec Frequency Response Optimisation Manual page 9

GOLDBERG AND MÄKIVIRTA
reduced after equalisation, which indicates that equali-
sation compensates well for the loudspeaker loading.
A better match across subbands of the average sub-
band median level demonstrates that equalisation has
improved the broadband flatness. The largest im-
provement is seen in the three-way loudspeakers. In
the two-way systems the equalisation has improved
broadband flatness only marginally as the subband
median levels do not show major signs of change. The
broadband flatness improvement is mainly the result
of better alignment of the LF subband with the MF
25% to 75% Percentile Difference
Level, dB
Change due to Equalisation - All models
1
0
Broadband LF
-1
-2
-3
25% to 75% Percentile Difference
Level, dB
Change due to Equalisation - Small models
1
0
Broadband LF
-1
-2
-3
25% to 75% Percentile Difference
Level, dB
Change due to Equalisation - 2-way models
1
0
Broadband LF
-1
-2
-3
25% to 75% Percentile Difference
Level, dB
Change due to Equalisation - 3-way models
1
0
Broadband LF
-1
-2
-3
Figure 4. Change in sound level deviation due to equalisation. For each subband, quartile difference and RMS de-
viation from the median. The error bar indicates the standard deviation.
AES 23RD CONFERENCE, May 23-25, 2003
MF HF
MF HF
MF HF
MF HF
AUTOMATED IN-SITU EQUALISATION
and HF subbands. This indicates that the equalisation
has not only reduced the variation inside individual
subbands but also improved the broadband flatness of
the acoustical response, translating to a reduced
colouration of the audio at the listening position.
For all loudspeakers pooled together (Figure 3), the
equalisation reduces the variance in the median level
for the LF subband. A similar outcome is noted sepa-
rately for each loudspeaker type. However, only in the
three-way systems is an improvement seen also in the
MF and HF subband variance.
RMS Deviation
Level, dB
Change due to Equalisation - All models
1
0
Broadband LF
-1
-2
-3
-4
-5
RMS Deviation
Level, dB
Change due to Equalisation - Small models
1
0
Broadband LF
-1
-2
-3
-4
-5
RMS Deviation
Level, dB
Change due to Equalisation - 2-way models
1
0
Broadband LF
-1
-2
-3
-4
-5
RMS Deviation
Level, dB
Change due to Equalisation - 3-way models
1
0
Broadband LF
-1
-2
-3
-4
-5
MF HF
MF HF
MF HF
MF HF
9