|Yes, you can.|
Record a 60 second file, without any sound input. Save as "blank1.wav", then repeat, saving as "blank2.wav". Go to edit > Insert File, and select blank1.wav. You'll now see the length is 120 seconds. You can repeat this as many times as needed to get the length you need (saving each time). When you are happy with the length, use this as a template for your recording.
A quicker way is to use a copy of a wav file (of appropriate length) and record over it. You may need to change the format (in the save as window) to PCM.
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