Fwd: sound stopped working after upgrade

[Mike Izbicki <mike@izbicki.me>]

>> I *think* the fundamental problem is that /dev/dsp doesn't exist.  For
>> example, when I run mplayer, I get the following output:
>
> My sound works and I do not have a /dev/dsp

That's the specific error message I was getting from mplayer though.

I also just ran the `alsaloop` program, which gave the following
output not related to /dev/dsp:
```
ALSA lib pcm_hw.c:1401:(_snd_pcm_hw_open) Invalid value for card
playback hw:0,0 open error: No such file or directory
Loopback initialization failure.
```

>> Running alsamixer shows a master channel and a capture channel, both
>> of which are set to max volume.
>
> Do they show that the channels are unmuted ?

Yes

> Do you have 1 and only 1 audio "sink" ? If not you may have a problem with pulseaudio not sending audio to the correct sink.

How do I check this?  When I run alsamixer and hit F6 to select the
sound card I get two options: default and "enter device name".

> Also check dmesg for any references to audio devices.

Running `dmesg | grep -i audio` gives no output.  (The -i makes grep
case insensitive.)