Flat waveform, noisy sound in Ubuntu hardy heron

[Reploid]

Hi folks.

I am using Audacity 1.3.4-beta on ubuntu hardy heron.

Recording with my Senheiser headset works fine in windows with the sound recorder.
Windows recorded files can be played back just fine in Audacity.
But recording with Audacity doesn't give me decent sound, it sounds noisy, and it looks as if the wavepatterns have been cut off with a pair of scissors.

I have tried to lower the input sound in alsamixer, and it lowers the red meter toolbar, and the amplitude upon recording is lowered, but the waveform is still flat, and sound is still crap.

Thus, I am not sure what the cause of this problem might be, it doesn't look like the "clipping" described in the wiki.

Any help would be greatly appreciated!

[steve]

It probably is clipping, but not as severe as is generally shown.
You are most likely overloading either the microphone, or the microphone input.

When you turn down the level in ALSA mixer "capture" control, it is reducing the level of the signal that is sent to Audacity, but the "damage" (distortion) has already been done.

Turn up the capture control to max (100%) - this will allow you to record up to "full scale" in Audacity.
Depending on how badly it is distorting, either talk more quietly, or turn off the 20 dB boost for the microphone input. If the recording is a bit too quiet with the "microphone boost" switched off, you can amplify it after your recording is complete.

Do try to avoid your breath hitting the microphone as this will mess up the recording quite badly. Also, remember that the "mic in" on a computer is not generally designed for high quality recording, and usually they are little better than telephone quality.

(My guess is that turning off the "boost" will fix it).

[Reploid]

Thanks, Steve. But where do I switch the mic boost off?

[steve]

In your mixer applicateion (for example ALSA mixer)

[Reploid]

Steve, I can't find any "mic boost" option in my alsamixer, nor under alsamixer-gui. I must be blind, because I have been playing around with it for some time. Have a look at a picture from my alsamixer, under the Capture tab:

[steve]

Good heavens , is that the only controls you have in Alsa mixer? My one has got dozens of sliders and switches (well a lot more than that anyway).

It looks like only basic functionality is supported by your Linux soundcard driver. You could ask your sound card manufacturer for a Linux driver (laughs out loud ironically).

More realistic solutions, you could search Google for Linux help for your particular soundcard, or get a new soundcard. I use a SoundBlaster Live Value, which if you can still find one (they are old) give good results, work well with Linux, and are cheap.

[Reploid]

Dozens of sliders under the "capture" options? I have more under "all," but they don't seem to help. Anyway, thanks a lot for your help, steve. If the soundcard drivers and lack of customization with the linux drivers is the reason behind the clipping, at least that explains why I couldn't find a solution by searching. I'll probably get myself a supported USB interface for my laptop anyway.

Funny how people can hear me just fine in skype, though.

[steve]

Funny how people can hear me just fine in skype, though.

Ah, that changes things - you didn't mention that before. Can you post a screenshot to show what you mean by "it looks as if the wavepatterns have been cut off with a pair of scissors" so that I can see what you mean.