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Sidetone: The Best Calling Feature You Never Heard Of

By Michael Fisher September 21, 2012, 11:45 am

At Pocketnow, we've recently reviewed a lot of Motorola phones. My own Moto kick started with my Atrix HD review a few months back, followed quickly thereafter by one for the Photon Q 4G LTE and Droid RAZR M. We'll no doubt get our hands on one or both of the new RAZR HD family, as well, and maybe even the RAZR i, if we're feeling like bringing a little Intel inside.

I tend to enjoy Motorola handsets, so I'm pretty happy with the increased prominence the company has enjoyed in our review lineup of late. They generally feature good build quality, solid heft in the hand, good radio performance ... and something few people ever talk about in this age of the ever-dwindling importance of the voice call.


That something is called "sidetone." It's been around since the nineteenth century, and it's the most important voice-calling feature you've probably never heard of. Motorola isn't the only company that's built it into mobile phones, but it was (at least one of) the first to introduce it into cellular telephony, incorporating the feature into the revolutionary StarTAC. Motorola has also been one of the most consistent in its implementation over the past decade or so.

So What Is It?

Merriam Webster defines sidetone as "the sound of a speaker's voice as received at his own ears."

There’s also the other, more-haughty definition.

If you've ever used a home telephone ( **young people: ** this is an artifact from the days of old, powered by copper wires strung across the countryside on wooden poles) sidetone should be a familiar concept. It's that little bit of controlled feedback you hear through the earpiece that helps your modulate your voice, speaking neither too loudly nor too softly. It's not "feedback" in the traditional sense, in that it doesn't carry an echo. It's just a barely perceptible augmentation of your own voice -about 8%, if you believe the faceless goons behind Wikipedia- coming through the earpiece.

Why Is It Important In Mobile?

A feature that's been around as long as sidetone has clearly proved its worth. The thing is, as important as it's become to landline telephony, it's an even more crucial in the mobile world. Why?

This guy knows.

The first reason is the overall user experience. Without sidetone, talking on a mobile phone feels exactly like what it is in reality: holding a piece of plastic to your ear and speaking out loud. There's no feeling of connection, no audio "interface" between you and the device; your voice just propagates outward as it would in any other situation, lost to the ether. This is a bigger deal in mobile than it is with landlines because home phones are usually confined to a room in a house, where audio conditions tend to be consistently good (unless you have children, I suppose). In mobile, the reassuring warmth of sidetone is doubly important because you could be calling from literally anywhere— a taxicab, a crowded bar, a windswept field, a trading floor, or an echoey bathroom. And if you do the latter, please stop reading and leave and never call me again.

Another reason is something I'll call "connectivity reassurance." Landline communication long ago reached such a point of extreme reliability that disconnected calls are today an almost unheard-of event, but despite the rapid evolution of cellular networks over the past decade, that's not the case with mobile phones. Dropped calls are still an unfortunate reality, as any wireless carrier will (reluctantly) admit. Sidetone helps you realize when you've dropped a call because instead of hearing your voice pleasantly redirected to your earhole at about 4% intensity (again, if you believe the scantily sourced but well-written Wikipedia entry on sidetone), you hear nothing. You hear the harsh silence of the outside world swallowing up your voice. Because you are, in fact, just talking to a disconnected piece of plastic.

“The stark emptiness of my life is overwhelming.”

That's Awesome.

I agree! The dropped-call issue is less pressing today than in ages past, with most OEMs having built handy audio notifications into their dialer software that alert you when your call fails. Still, it's a very important feature from the broader user-experience perspective, maybe akin to haptic feedback or kinetic UI scrolling in smartphones. It's just one of those nice, subtle touches that helps deliver the feel of a premium experience.

Fortunately, though voice calls have fallen from grace somewhat, we're seeing an increased focus on call quality as manufacturers continue striving to set themselves apart from the pack. From Motorola's CrystalTalk noise reduction technology, to the three-microphone noise-cancellation approach found on the iPhone 5, to (delayed) rollout of new technologies like VoLTE, OEMs and carriers are sprucing up the long-neglected voice-calling sector once again. You can bet that, in the midst of increased bandwidth and newfangled ways to keep that idling dump truck's engine noise from mucking up your call, sidetone will continue playing an important part. So next time you're on a phone call home, throw a little thanks to this ancient technology for making your mobile phone calls warmer, easier, and generally more enjoyable.

Now look away while I cite this Wikipedia article I've been dogging for the past thousand words.

Dick Tracy watch photo source: The Cool Kidz Table

Sidetone information: Merriam-Webster, DreamWave, Wikipedia


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