Audio files dragged to Ableton Live tracks are automatically set to conform to any tempo changes that are made to the session. Sometimes , especially if you wish to use Abletone Live as a conventional DAW you might not want tracks to "conform" to the set tempo.
Here's how you disable this feature.
Go to the top menu Live / Preferences
Then in the dialog box that appears select the side menu that says Record/Warp/Launch
Then set Auto-Warp Long Samples to Off
Now if you drag and drop an audio file to a track (not a clip) it will retain it's original speed irrespective of the tempo live is set to.