That was the coolest thing, hearing the female voice saying 'Initializing startup sequence, and Initializing shut-down sequence' or something like that. Think that the voice is a knoppix thing though I'm pretty sure you could do it on just about anyone linux computer and have it play just about any sound file. If the computer is off, turn it on, then immediately insert the Knoppix CD/DVD. To play for time, press the Pause/Break key immediately after turning your computer on. On many PCs and laptops, this will pause the BIOS, giving you more time to insert the CD/DVD. Then press the Pause/Break key again to resume startup.

1. Ogg Sound Effects
2. Downloadable Ogg Sound Files
3. Knoppix Startup Ogg Sound Files Free

You will need a sound file in the .ogg or .wav format. Rename the file into desktop-login.ogg( wav ) and place it in the
/usr/share/sounds folder. Rightclick and choose New Window As Administrator in order to be able to place the file there :
In System Settings ( Applications > System Settings ) go to Startup Applications > Add.



Name : Login sound
Command : /usr/bin/canberra-gtk-play --id='desktop-login'

Then Add....
Download sounds from here.
More sounds : http://www.zedge.net/ringtones/0-7-1-startup%20sound/( download with Save Link As... ).
Knoppix sounds.
Free online audio convertor : http://audio.online-convert.com/Categories: Linux
Codecs and formats aren't an issue anymore in Linux, especially in user-friendly distributions like Ubuntu and Linux Mint. Although Flac is a superior format to MP3, it isn't supported by devices (or players) as widely as MP3. Converting .flac files to .ogg or .mp3 is a simple affair with the correct applications installed.
Depending on your Linux distribution setup, users will have to install Lame MP3 encoding library and an audio converter using your package manager of choice. The screenshots below depict Ubuntu Software Center in Ubuntu Unity

Ogg Sound Effects

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Downloadable Ogg Sound Files

Knoppix Startup Ogg Sound Files Free

1. Using Ubuntu Software Center, search for the LAME MP3 Encoding Library. The package itself allows you to convert a variety of sound formats to MP3 via command line. If you're comfortable with following simple commands in a Terminal, then you're all set.
2. For users who prefer a graphical interface, Sound Converter is the simplest utility available for the Gnome desktop (and works perfectly in Unity too). Search for Sound Converter and install the application using the Ubuntu Software Center. Related plugins are offered for installation - the popular gstreamer multimedia set of plugins (scroll to view the check boxes). Gstreamer plugins have long-been used in open source for supporting a variety of codecs and containers so they're highly recommended.
3. Launch Sound Converter. By default, Sound Converter will convert to the open source format .ogg so click Edit and Preferences before starting any conversion tasks.
4. Under Format, select .mp3. If needed, change output folder location and other preferences. Click Close.
5. On the main Sound Converter window, click Add Folder or Add Files. Click Convert to begin converting .flac files or other audio formats to .mp3.