Twice a day my mouth turns into a cavernous venue for what could be mistaken for a solo didgeridoo concert. This is when I use my electric toothbrush. It’s battery-charged, and takes close to half a day to get enough power for it to last a few weeks. I know the toothbrush is due for a charge when the light persists in blinking after I’m done brushing. I know I’m done brushing because the room, along with my mouth, goes silent. Previous to that silence, for two minutes straight from start to finish, my mouth reverberates with the sound and sensation of bristles going full speed.
When I first started using the electric toothbrush, after a lifetime with the unplugged sort, I was concerned I’d made a terrible and not inexpensive mistake. Those vibrations are my least favorite part of my thrice-annual dental visit. There’s a quiet ferocity to them, and the hum of the machine is matched by the ticklish tinging where gums meet teeth. After a short time, thankfully, I became comfortable with the brush, and now I rarely travel without it. I came, in fact, to admire the vibrations, or more specifically the use of the vibrations as a design element.
There’s a particularly ingenious aspect to the electric toothbrush’s vibrations. Every 30 seconds there is a lull, not a cesura, just the briefest of pauses. The lull is a signal. It means rotate, like we used to do in volleyball during gym class back in high school. The brush is programmed to match the quadrants of a human mouth: front top, front bottom, back top, back bottom. The lull, a split-second drop in the rotary drone, is a signal to switch quadrants. Kudos to the device’s designers, who opted to use the absence of sound as a cue, rather than adding a beep. The absence of sound is one of the great tools in a sound designer’s toolbox. It’s a difficult choice for a designer to leave something out, rather than to add something.
The lack of a beep in the brushing is matched by that battery alert. It’s risky to have something as important as battery life be gauged simply by a little light. What if you put down the toothbrush quickly after brushing? What if you place it on the counter so the light is turned away from you? What if the bathroom is brightly lit? No matter. This brush would rather you learn the hard way. One cycle back with the archaic “manual”brush is a small price to pay to be trained to keep an eye on that light in regard to your toothbrush’s battery life. The absence of the beep as an alert, for both the quadrant-swapping and the battery notification, feels like a conscious acknowledgement of the utility scenario, of the quiet period when brushing takes place: early in the morning and late in the evening. Those are times when any additional noise is especially unwelcome, in life and in consumer-product design.