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I have a USB microphone.

$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

$ cat /proc/asound/cards
 0 [ALSA           ]: bcm2835 - bcm2835 ALSA
                      bcm2835 ALSA
 1 [Device         ]: USB-Audio - USB PnP Sound Device
                      C-Media Electronics Inc. USB PnP Sound Device at usb-20980000.usb-1.4, full spe

But when I run alsamixer, I get the following:

This sound device does not have any capture controls.

The problem is that the recording sound level is to low, and I want to increase the microphone sensitivity. How can I do that?

$ arecord -D plughw:1 -d 5 -vv ~/rectest.wav
Recording WAVE '/home/pi/rectest.wav' : Unsigned 8 bit, Rate 8000 Hz, Mono
Plug PCM: Rate conversion PCM (48000, sformat=S16_LE)
Converter: libspeex (builtin)
Protocol version: 10002
Its setup is:
  stream       : CAPTURE
  access       : RW_INTERLEAVED
  format       : U8
  subformat    : STD
  channels     : 1
  rate         : 8000
  exact rate   : 8000 (8000/1)
  msbits       : 8
  buffer_size  : 4000
  period_size  : 1000
  period_time  : 125000
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 1000
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 4000
  silence_threshold: 0
  silence_size : 0
  boundary     : 262144000
Slave: Hardware PCM card 1 'USB PnP Sound Device' device 0 subdevice 0
Its setup is:
  stream       : CAPTURE
  access       : MMAP_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 1
  rate         : 48000
  exact rate   : 48000 (48000/1)
  msbits       : 16
  buffer_size  : 24006
  period_size  : 6000
  period_time  : 125000
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 6000
  period_event : 0
  start_threshold  : 6
  stop_threshold   : 24006
  silence_threshold: 0
  silence_size : 0
  boundary     : 1573257216
  appl_ptr     : 0
  hw_ptr       : 0
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  • It might mean there's simply nothing about it you can tune (e.g., input level). Does it work for recording? – goldilocks♦ Jan 6 '17 at 20:17
  • Uh, what is the problem? Why do you think that this device should have some mixer control? – CL. Jan 6 '17 at 23:08
  • The problem is that the recording sound level is to low, and I want to increase the microphone sensitivity. How can I do that? – max5555 Jan 7 '17 at 8:37
  • You should modify your /etc/asound.conf, or ~/.asoundrc, and add a softvol element after the microphone. This will do software amplification of the microphone signal. – Étienne Jan 9 '20 at 10:50
1

did you increase volume in 'alsamixer'. Open alsamixer and Press F6 and select sound card. Press F4 for capture device use <> and up dow

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You should modify your /etc/asound.conf, or ~/.asoundrc, and add a softvol element after the microphone. This will do software amplification of the microphone signal.

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