I'm setting up alexa-pi and everything was going smoothly until the final step which is running a wake word engine. I'm keep getting " 'pcm' failed." error. I've read somewhere that in order to this to work first I need to make sure that arecord -d 10 -f S16_LE -r 16000 test.wav command would record my voice input, however when I try to run it I get

arecord: main:722: audio open error: No such file or directory

Here's some of my outputs

~$ cat /proc/asound/modules 
 0 snd_bcm2835
 1 snd_usb_audio

~$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: Mic122033996 [Wireless Mic #122033996], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Also I had to put this .conf file in /etc/modprobe.d/ so alsa can see my microphone (it couldn't before)

# This sets the index value of the cards but doesn't reorder.
options snd_usb_audio index=1
options snd_bcm2835 index=0

# Does the reordering.
options snd slots=snd_bcm2835,snd_usb_audio

and here's whats wake word engine throws:

$ ./wakeWordAgent -e sensory
INFO:main: Starting Wake Word Agent
INFO:WakeWordAgent: State set to IDLE(2)
INFO:Initializing Sensory library | library name: TrulyHandsfree | library version: 5.0.0-avs.1 | model file: ../ext/resources/spot-alexa-rpi.snsr
WARNING:Library expires on: License expires on 28 Apr 2017 00:00:00 GMT
wakeWordAgent: pcm.c:694: snd_pcm_close: Assertion `pcm' failed.

2 Answers 2


Ok, I've solved my problem replacing ~/.asoundrc file with this content

pcm.!default { type asym playback.pcm { type plug slave.pcm "hw:0" } capture.pcm { type plug slave.pcm "hw:1" } }
  • I would suggest you instead just specify the device in the arecord command. Setting hot-pluggable devices as default in the asound file will cause you trouble later. From experience.
    – Hydranix
    Jan 12, 2017 at 23:36
  • Please accept your own answer with a click on the tick on its left side. Only this will finish the question and it will not pop up again year for year.
    – Ingo
    Dec 20, 2019 at 23:56

Try this command:

arecord -D hw:1,0 -d 10 -f S16_LE -r 22050 test.wav

-D sets the device specifically, otherwise it may be trying to use a non existant input device on hw:0.

You can also set your soundcard index for snd_usb_audio to index=0 and the snd_bcm2835 to index=1 but specifying the device in the command is more reliable.

Further, though maybe not required for this, make sure you have this line in your /boot/config.txt

  • Thanks, but like I said that doesn't solve my problem arecord -d 10 -f S16_LE -r 16000 test.wavshould work without specifing any devices and only then maybe I can get a wake word engine to work
    – gosu94
    Jan 12, 2017 at 21:44
  • arecord without specifying a device will try to use the default device. The default device will be whatever you have set in your /etc/asound.conf or ~/.asoundrc.
    – Hydranix
    Jan 12, 2017 at 23:32
  • See updated answer with the dtparam setting. I know on archlinux i had trouble with audio until I set that.
    – Hydranix
    Jan 12, 2017 at 23:34

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