replace in opening quotations

node173.html

@@ -86,8 +86,8 @@ Block diagram for narrow-band noise suppression by companding.</CAPTION>
 A
 <A NAME="12582"></A><I>compander</I>
 is a tool that amplifies a signal with a variable gain, depending on the
-signal's measured amplitude.  The term is a contraction of ``compressor" and
-``expander".  A compressor's gain decreases as the input level increases, so
+signal's measured amplitude.  The term is a contraction of "compressor" and
+"expander".  A compressor's gain decreases as the input level increases, so
 that the
 <A NAME="12584"></A><I>dynamic range</I>,
 that is, the overall variation in signal level, is reduced.  An expander does