Tape loops of the transient responses were played back into a transfer
function analyzer (TFA). The input and response signals were
processed by using the tracking filters in the TFA to filter and ratio
the response to the input signal, thereby estimating the frequency
response between the input signal and the response signal. This
method proved to be impractical due to signal-to-noise problems.
However, it triggered the investigation of other methodologies
including Fourier analysis.