免費又開源的 Audacity，剪聲音、去雜訊、轉檔夠用嗎

What's new in this version:

# Changes between 1.3.14 and 2.0.0
* Bug fixes
- Interface
> Fixed playback speed and synchronization problems when dragging clips or tracks between tracks having different sample rates.
> (Windows) Removed a crash risk where shortcuts could be used to record or import in one project while importing or exporting in another. 
- Imports and Exports
> Fixed crashes when changing the sample format of read-directly WAV or AIFF files using the Track Drop-Down Menu.
> Fixed a crash importing MP3 files that had duplicate metadata tags (this is a bug in current libsndfile which has been patched in Audacity; MP3 files mislabeled as WAV which have duplicate tags will still crash Audacity on Linux if Audacity has been compiled against an affected version of system libsndfile).
> Fixed an issue where excessively high or corrupted sample values in the audio could corrupt exports from the start of the problem for the rest of the file, and could corrupt the rest of the project.
> (Linux) Fixed Audacity could not be compiled against FFmpeg 0.7.x and 0.8.x. 
- Effects and Analysis
> Fixed crash on launch when using "Ambisonic Decoders (PC)" VST plug-ins and other plug-ins that enable additional floating point exceptions.
> Fixed Plot Spectrum background could be transparent on some machines.
> Bug fixes for Click Track, High Pass, Low Pass and Vocal Remover.
> Chirp, Tone and Silence generators now remember their settings. 
* Changes and Improvements
- New Interface preference to show the track name in the display (this is off by default).
- Longer default Playback preference for effects preview and preview before cut.
- Restored use of Page Up and Page Down to scroll horizontally. 
# Summary of bug fixes and new features between 1.2.6 and 2.0.0
* Bug Fixes
- Labels now accept lower case "z".
- (Windows Vista/7) Pressing Stop after recording could cause a crash.
- (Mac OS X) Fixed shortcut keys activating when typing in file open or save windows.
- (Mac OS X) Audacity 2.0.0 fully supports Unicode, which fixes an issue where Audacity could not work with folders having non-English characters in their name.
- (Linux) Playing existing tracks while recording in mono could cause recordings to be distorted or low-pitched. 
* New features
- Many effects significantly improved, especially Equalization, Noise Removal and Normalize. Vocal Remover now included plus GVerb on Windows and Mac. VAMP analysis plug-ins now supported.
- Improved label tracks with Sync-Lock Tracks feature in the Tracks Menu.
- Multiple clips per track. Tracks and selections can be fully manipulated using the keyboard. Many more keyboard shortcuts.
- New Device Toolbar to manage inputs and outputs. Timer Record feature. New Mixer Board view with per-track VU meters.
- Automatic Crash Recovery in the event of abnormal program termination.
- Fast "On-Demand" import of WAV/AIFF files if read directly from source.
- FLAC now fully supported. Added support for optional FFmpeg library for import/export of AC3/M4A/WMA and import of audio from video files.