Since Fig. 6 indicates the existence of fixed and angle-dependent components in the measured impulse responses, and since such angle-independent component is strongly suppressed by baffling in the cabinet enclosure, it is desirable to eliminate this fixed component from the measurements. For this purpose, an iterative algorithm was developed which models the two components separately.

Let denote the number of impulse-response samples in each
measured impulse response,and let denote the number of angles
(`-180:15:180`) at which impulse-response measurements were
taken. We denote the impulse-response matrix by
.
Each column of
is an impulse response at some horn angle.
(Figure 6 can be interpreted as a plot of the *transpose* of
.)

We model as

diag

where is the arrival-time delay, in samples, for the horn
output in the th row (the delays clearly visible in Fig. 6 as
a function of angle). These arrival times are estimated as the
location of the peak in the cross-correlation between the th
impulse response and the same impulse response after converting it to
minimum phase [11]. The diagonal matrix
diag denotes a Each column of the matrix contains a copy of the estimated horn-base leakage impulse-response:

The estimated angle-dependent impulse-responses in
are modeled as
linear combinations of *fixed* impulse responses, viewed
(loosely) as *principal components*:

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