The scale doesn't matter most of the time and the label of that scale almost never matters.
In a broad sense, the user only wants volume controls with 2 settings: Off and the correct/desired volume. If the user is adjusting things up or down it's because they are trying to reach whatever the correct volume is. Most likely the situation has changed and what was previously the correct volume is not longer acceptable.
The specific correct "value" for the volume control is not known ahead of time. The user's mental model is not "Turn the radio on and set the volume to 26.7dB" or "Someone just turned a blender on, I need to set my volume to 90dB." It's closer to "I can't hear my song anymore. It needs to be louder."
Regardless of the scale chosen for the control, the feedback loop to select the correct volume is the same. Is this loud enough? No? Turn it up one notch. Repeat. They aren't going to stop at 60% or 45db or any other predetermined number so the labels don't make any difference. They are going to stop when they can hear what they want to hear.
A good system would determine what correct volume is and try to make it happen without user input. You see this with automatic volume control (AVC) systems in cars where it detects the ambient background noise and adjusts the volume to compensate so that the user doesn't have to keep fiddling with the controls.
sqrt(2)volume). On a logarithmic (or audio) pot, 50% means 50% volume.