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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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2 Answers 2

Reset to default
2

Try recording at higher quality e.g.:

arecord -D plughw:1 -c1 -r 48000 -f S32_LE -t wav -V mono -v listen-usb.wav

or (which is CD quality)

arecord -D sysdefault:CARD=1 -d 10 -f cd -t wav f2.wav

The noise tends to go away. The man page for arecord gives more options.

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If you can afford the space always go for the CD quality. It otherwise has very poor quality on the RPI. I've tried many USB microphones of varying quality including Blue Snowball and all have this background static sound to some degree unless you use record at CD quality as shown in the Greenonline,FishFace post:

    arecord -D sysdefault:CARD=1 -d 10 -f cd -t wav f2.wav

Then even the cheapest usb mic sounds pretty good. I paid $6 each for my no-name USB gooseneck mics.

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3
  • 1
    You essentially repeat what's already written in the other answer. I have no problem with that, but is it really useful?
    – Dmitry Grigoryev
    Dec 9, 2019 at 13:08
  • I spent several days messing around with other recording parameters and a variety of microphones. When I tried the CD parameters, Hallelujah! I had clarity. I just wanted to emphasize that this is the way to go and not waste time.
    – Gary Feierbach
    Dec 10, 2019 at 20:03
  • Yeah, I know it sucks not to be able to upvote or comment.Since two people agree on a solution, I deem it safe to assume it's the correct one, so I'll upvote you both. However, note that you still could have posted a very different answer, even if the end solution is the same. For instance, you could have written about how to estimate noise level with Audacity, or posted a table with your test results to emphasize just how much of improvement the CD quality brings. In any case, be welcome here and assured that if you're someone who spends days trying things out, you'll gather rep in no time.
    – Dmitry Grigoryev
    Dec 11, 2019 at 8:40

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