Finished (:D) fig_invariance_log_hp.pdf.

Added movable label string to time_bar().

main.tex

@@ -47,6 +47,12 @@
 % \newcommand{\eref}[1]{\mbox{\cref{#1}}}
 % \newcommand{\eref}[1]{\mbox{Eq.\,\ref{#1}}}
 
+% Subplot lettering:
+\newcommand{\figa}{\textbf{a}}
+\newcommand{\figb}{\textbf{b}}
+\newcommand{\figc}{\textbf{c}}
+\newcommand{\figd}{\textbf{d}}
+
 % Math shorthands - Standard symbols:
 \newcommand{\dec}{\log_{10}} % Logarithm base 10
 \newcommand{\infint}{\int_{-\infty}^{+\infty}} % Indefinite integral
@@ -625,23 +631,25 @@ the signal for reliable song recognition.
     \includegraphics[width=\textwidth]{figures/fig_invariance_log_hp.pdf}
     \caption{\textbf{Intensity invariance by logarithmic compression and
                      adaptation is restricted by the noise floor.}
-                     Envelope $\env(t)$ is transformed into logarihmically
-                     compressed envelope $\db(t)$ and further into
-                     intensity-adapted envelope $\adapt(t)$. Indicated time
-                     scale is $5\,$s for both \textbf{a} and \textbf{b} (black
-                     bars).
-                     \textbf{a}:~Ideally, if $\env(t)$ consists only of song
-                     component $\soc(t)$ rescaled by $\sca$, then $\adapt(t)$
-                     is fully intensity-invariant across all $\sca$.
-                     \textbf{b}:~In practice, $\env(t)$ also contains
-                     fixed-scale noise component $\noc(t)$, which limits the
-                     effective intensity invariance of $\adapt(t)$ to
-                     sufficiently large $\sca$.
-                     \textbf{c}:~Ratios of the SD of each representation in
-                     \textbf{b} at a given $\sca$ relative to the SD of the
-                     representation for $\sca=0$ (solid lines). The same ratios
-                     for the ideal $\adapt(t)$ in \textbf{a} are shown for
-                     comparison (dashed line).
+                     Synthetic input $\filt(t)$ consists of song component
+                     $\soc(t)$ scaled by $\sca$ with (\figc{} and \figd) or
+                     without (\figa{} and \figb) additive noise component
+                     $\noc(t)$. Input $\filt(t)$ is transformed into envelope
+                     $\env(t)$, logarithmically compressed envelope $\db(t)$,
+                     and intensity-adapted envelope $\adapt(t)$.
+                     \textbf{Left}:~$\env(t)$, $\db(t)$, and $\adapt(t)$ for
+                     different scales $\sca$.
+                     \textbf{Right}:~Ratios of the standard deviation of
+                     $\env(t)$, $\db(t)$, and $\adapt(t)$ relative to the
+                     respective reference standard deviation for input
+                     $\filt(t)=\noc(t)$.
+                     \figa{} and \figb:~Ideally, if $\filt(t)=\sca\cdot\soc(t)$, then
+                     $\adapt(t)$ is intensity-invariant across all $\sca$.
+                     \figc{} and \figd:~In practice, if
+                     $\filt(t)=\sca\cdot\soc(t)+\noc(t)$, the intensity
+                     invariance of $\adapt(t)$ is limited to sufficiently large
+                     $\sca$. Shaded area indicates saturation of $\adapt(t)$ at
+                     $95\,\%$ curve span.
                      }
     \label{fig:inv_log-hp}
 \end{figure}