You can very simply record audio through terminal using the pre-installed tool arecord.

  1. Open a terminal (Ctrl+Alt+T)
  2. Run the command

    arecord filename.wav
    
  3. Your audio recording has started, press Ctrl+C to stop the recording.

  4. Your voice recording has been saved as filename.wav in your home directory.

EDIT:
If you have multiple inputs you can find them using

arecord -l

which will list hardware devices that can then be selected using the -D flag. Listing looks like...

**** List of CAPTURE Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC269VB Analog [ALC269VB Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

When choosing a particular device I used the following to select a USB headset.

arecord -D hw:1,0 -f S16_LE filename.wav    

Note that the device selection was based on the following listing which comes straight from the -l listing.

card 1: Headset [HP Digital Stereo Headset], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Try Audio Recorder.

Audio Recorder is a recording program, that allows user to record audio from various sources, and allows you to save recording in various formats.

To install, just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:

sudo add-apt-repository ppa:osmoma/audio-recorder
sudo apt-get update
sudo apt-get install audio-recorder

For Ubuntu versions higher than 15.10 there is a new ppa which can be found at https://launchpad.net/~audio-recorder/+archive/ubuntu/ppa

sudo add-apt-repository ppa:audio-recorder/ppa
sudo apt-get update
sudo apt-get install audio-recorder

Make sure your microphone is connected to your computer and well configured. Run this command: alsamixer to check your microphone level.

Also you can use sox to record your voice, it can be installed from the Ubuntu Software Center, r install it from the terminal with this command:

sudo apt-get install sox

Edit

You can also look at Ardour.

Ardour is a powerful digital audio workstation that gives you everything you need to record, edit, mix, and arrange professional audio.Ardour

To download, and more info, check out their website

Other programs to look at are MHWaveEdit, and KWave


I always prefer shell commandline, I use below command to record voice:

avconv -f pulse -i default /home/$USER/Music/$(date +"%m%d%Y_%H%M%S_$HOSTNAME")_screencast.wav

to stop it press q

UPDATE:

Ubuntu switched to FFMPEG again as of Ubuntu 15.04 "Vivid Vervet"

The above command will continue to work by replacing avconv with ffmpeg

ffmpeg -f pulse -i default /home/$USER/Music/$(date +"%m%d%Y_%H%M%S_$HOSTNAME")_screencast.wav

Another one to look for is gnome-sound-recorder, it was added in 2014. It is simple and just records input from the mic.

It is packaged 16.04 in the universe repo (named gnome-sound-recorder).