Hi all, In my Linux machine, I connected the plantronics usb headset with mic and I see(with the help of dmesg) that this device detected. [116676.507868] usb 2-2: new full-speed USB device number 5 using xhci_hcd [116676.923445] usb 2-2: New USB device found, idVendor=047f, idProduct=c012 [116676.927091] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [116676.934252] usb 2-2: Product: Plantronics .Audio 628 USB [116676.941445] usb 2-2: Manufacturer: Plantronics [116676.945731] usb 2-2: ep 0x84 - rounding interval to 64 microframes, ep desc says 80 microframes [116677.078071] hidraw: raw HID events driver (C) Jiri Kosina [116677.159669] usbcore: registered new interface driver usbhid [116677.161686] usbhid: USB HID core driver [116677.175458] input: Plantronics Plantronics .Audio 628 USB as /devices/pci0000:00/0000:00:14.0/usb2/2-2/2-2:1.3/0003:047F:C012.0001/input/input4 [116677.234588] plantronics 0003:047F:C012.0001: input,hiddev0,hidraw0: USB HID v1.00 Device [Plantronics Plantronics .Audio 628 USB] on usb-0000:00:14.0-2/input3 [116677.281756] usbcore: registered new interface driver snd-usb-audio The following nodes are present in the /dev/snd $ ls -l /dev/snd/ total 0 drwxr-xr-x 2 root root 60 May 12 11:32 by-id drwxr-xr-x 2 root root 60 May 12 11:32 by-path crw-rw---- 1 root audio 116, 2 May 12 11:32 controlC1 crw-rw---- 1 root audio 116, 4 May 12 11:32 pcmC1D0c crw-rw---- 1 root audio 116, 3 May 12 11:32 pcmC1D0p crw-rw---- 1 root audio 116, 1 May 12 11:32 seq crw-rw---- 1 root audio 116, 33 May 12 11:32 timer What are all these devices present in /dev/snd How do I use it for playing and recording an audio? Basically first I want to gain knowledge on set of test cases I can run on ALSA and then learn ALSA kernel modules stuff including snd_usb_audio mdule. So please guide me by providing related documentation/Steps. Thanks,