--- a/doc/interpreter/audio.txi
+++ b/doc/interpreter/audio.txi
@@ -25,8 +25,8 @@
 `sample' is a single output value from an A/D converter, i.e., a small
 integer number (usually 8 or 16 bits), and audio data is just a series
 of such samples.  It can be characterized by three parameters:  the
-sampling rate (measured in samples per second or Hz, e.g. 8000 or
-44100), the number of bits per sample (e.g. 8 or 16), and the number of
+sampling rate (measured in samples per second or Hz, e.g., 8000 or
+44100), the number of bits per sample (e.g., 8 or 16), and the number of
 channels (1 for mono, 2 for stereo, etc.).
 
 There are many different formats for representing such data.  Currently,