Volume (acoustics)
Multiple realities
(covers information from several alternate timelines)
Volume controls on a Nokia mobile device, 2241
In acoustics, volume was the level of a sound. Volume could be measured in decibels.
In 2267, Leonard McCoy asked if Rodriguez was the one calling him on the communicator because he was having a hard time hearing the lieutenant. Rodriguez affirmed McCoy's identification and explained that he couldn't get very good volume on the device, making it hard for him to hear McCoy, too. (TOS: "Shore Leave")