- Select all the audio clips.
- Open the Audiosnap palette (shotcut A).
- Choose Auto-stretch in the mode drop-down to the right of Clip Follows Project in the AS palette, and then click the Clip Follows Project button.
- Nothing will happen immediately, except maybe a re-draw of the waveforms, but as you start making tempo changes, the audio clips will follow them.
- Since the M:B:T ruler is the fixed visual time reference in SONAR, and the Now time cursor speed changes with tempo, you still won't see anything happening, but audio will audibly follow tempo changes along with any MIDI, which follows inherently.