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I try to use a USB microphone such as this or this on raspbian (tested on Linux raspberrypi 4.1.18, 4.9.41 and 4.9.59). It is in the list of lsusb Bus 001 Device 005: ID 0d8c:013c C-Media Electronics, Inc. CM108 Audio Controller Bus 001 Device 004: ID 046d:c52b Logitech, Inc. Unifying Receiver Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

and in the list of arecord --list-device **** 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

When capturing, I can only get a high background noise with a very low voice sound. I changed gain level from 100% to 70% with alsamixer and alsaclt without any change. In a noiseless environment, arecord --device=plughw:1,0 --duration=10 -vv atest.wav gives record at 61% (!?):

Recording WAVE 'atest.wav' : Unsigned 8 bit, Rate 8000 Hz, Mono
Plug PCM: Rate conversion PCM (48000, sformat=S16_LE)
Converter: linear-interpolation
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
###############################+                   | 61%

What is the tip to make it usable?

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