Where's the Volume Control?

At the exercise place, there's a machine I like called the Cardio Wave. (Click on this URL, hover your mouse over 'photo gallery', and click the bottom picture to see the touch screen.) This machine is controlled by a touch screen that doubles as a TV set. You can have your controls and indicators all over the screen, or you can make it a pure TV (it gets about 20 cable channels), or you can mix, with the TV screen inside the control screen. When I started using the Cardio Wave, of course I overdid it, but eventually I figured out that I can use it enjoyably with the following settings: On the touchscreen, I press “quick start”, and then I set its two controls to 3.

Most people who use this sort of machine will plug their headphones into it, but I usually set the channel to news (with captions) and listen to a podcast. One day however, I really wanted to hear what the TV announcer was saying, so I plugged my headphone jack into the Cardio Wave. But before I put the buds to my ears, I wanted to make sure the volume was low. Where was the volume control? I determined that there was no physical button to press, nor dial to turn; it had to be on the touchscreen. But what would that be? There were touch buttons to change the channel, and touch buttons to set my two exercise controls.

On further inspection, I was embarrassed to discover that one of the two controls I had religiously set to '3' was the volume.