One typo and two style issues:
--- sndio.7.orig 2012-12-21 17:55:39.415008759 +0100
+++ sndio.7 2012-12-21 18:01:20.607018154 +0100
@@ -44,7 +44,7 @@
while doing all necessary conversions on the fly.
It can mix multiple streams or split the hardware into
multiple subdevices, to allow programs to use the hardware
-concurently.
+concurrently.
.Pp
Hardware MIDI ports correspond to serial connectors provided by the
.Xr midi 4
@@ -56,7 +56,7 @@
Software MIDI thru boxes allow one application to send MIDI data to other
applications connected to the thru box (for instance a software sequencer
can send events to multiple software synthesizers).
-There's no hardware involved: thru boxes are created by
+There is no hardware involved: thru boxes are created by
.Xr sndiod 1 .
.Pp
Additionally,
@@ -123,7 +123,7 @@
.Fl fM
option on the command line.
.It Pa option
-Corresponds to the sub-device string registered using the
+Corresponds to the subdevice string registered using the
.Fl s
option of
.Xr sndiod 1 .
@@ -140,7 +140,7 @@
First audio device exposed by
.Xr sndiod 1 .
.It Pa snd/0.rear
-Sub-device registered with
+Subdevice registered with
.Fl s Fa rear .
.It Pa midithru/0
First MIDI thru box created with
