The iPhone is a really perfect starting point for diving into user interface sounds. First off, it’s one of the highest selling products in history (over 250 million, or 422M+ if you count all iOS devices), so chances are you’re very familiar with its sounds. Secondly, smartphones have, for better or worse, become extensions of our bodies. Sound is used to maintain that tether when our phone is out of sight or hand. Lastly, the iPhone uses a pretty large number of sounds, which all fall into one of the 4 flavors of UI sounds: Realistic, Symbolic, Metaphoric, and Verbal. (The Four Flavors Of UI Sounds)
Sounds Like Real Life: The iPhone’s Realistic Sounds
The iPhone’s lock and unlock sounds fit cleanly into the category of realistic UI sounds, as they both have the sound and feel of a metal spring lock. The iPhone of course has no physical lock and is made of a relatively tiny bit of metal. But by using sounds that evoke metallic qualities of solidness and security, these attributes are transferred in our minds to the iPhone itself. The sounds subtly communicate a facet of the phone’s carefully fabricated personality, while at the same time doing their primary duty of giving the user clear feedback on their phone’s lock or unlock state. Fun fact: The wonderful design podcast 99% Invisible explains that the lock sounds are actually recorded from the opening and closing of a vice grip (Link, jump to 2:45 for the part on the iPhone).
The iPhone’s camera sound works on us in a similar way as the lock sounds. It unequivocally sounds like a real, high-quality camera taking a picture – it’s purposefully not the clunk of an old analog camera or the ca-chunk of an electric 35mm point and shoot. This camera sound gives the user important feedback (“Your photo was just taken”) and also communicates and reinforces an essential feeling of quality to the user (“This little $200 rectangle is on par with a $2500 DSLR… I’m an artist, dude!”).
I’d guess that many might consider these sounds mostly ornamental and just another example of Apple’s overuse of skeuomorphism. While it’s true that the phone doesn’t have a shutter and the “lock” is purely digital, I think that the physicality and literal reference of the sounds are masterfully chosen to powerfully but subtly enhance our perception of the product’s personality (and in turn, Apple).
Earcon-omic: The iPhone’s Symbolic Sounds
The iPhone uses many symbolic sounds in its UI – these are sounds that are chosen to represent an action, but don’t sound like that action in any way. They’re sometimes called “earcons,” if you’re looking for a catchier name.
That click you hear when you type on the keyboard is essentially a quick nod from the iPhone telling you that your tap was understood. Using a short sound to let the user know their command went through is probably the most common use of sound in user interfaces. Since glass touchscreens lack the tactile feedback of pressing down a physical key, this is one of the best available options for giving this kind of user feedback. I’ve seen Android phones that use short vibrations for a similar effect.
A sustained D6 note is played when a voice memo begins recording. When your recording is stopped, that same sound is played back twice in a quick rhythm. This sound itself doesn’t reference anything about making a recording – Apple didn’t choose to use, say, the sound of an analog button push or mic feedback – but just by pairing these arbitrary notes with the voice memo app, we learn to associate the sound with the action.
The sounds Siri makes when turning on, off, or when she (it?) understands a command are 3 different pitched notes that use the same rhythm and timbre as each other. The problem with differentiating sounds by only their pitch is that most users are not going to have perfect pitch. People can generally notice pitch differences if the sounds are heard in relatively close succession, but in the context of Siri’s sounds, I’ve found that I lose my reference of the pitches after speaking to Siri for a few seconds. This means that when I’m driving, I sometimes just can’t tell if the beep-beep means I should repeat my message, Siri does understand me, or I turned Siri off and I’m just talking to myself again… This is one of the few instances of sound on the iPhone where I think Apple could have done a much better job.
Verbal
When Siri speaks back to give you information or asking to clarify your message, this of course an example of a verbal UI sound. In addition to providing a verbal interface for the phone, you can also use Siri to speak the text of websites back to you – an incredibly important feature for visually impaired users.
Metaphoric
The iPhone also uses sounds which metaphorically describe, through qualities of the sound itself, the action you’re performing. The woosh that plays when you send an email first rises in pitch and then fades into the distance. It wouldn’t be too out of place in a Pixar movie for when a toy rocket takes off, which is kinda, sorta like what happens when your email data takes off to travel the internet.
I’ve included the mail received sound in this section so it can be heard in the context of the mail sent sound. As you may notice, this sound (a sustained, somewhat bell-like Gb note) is purely symbolic and nothing about it references the action of receiving an email.
The text message send and receive sounds also use the bending of pitch to imply momentum and direction. When I send a text, the sound slides up and away. When I receive a text, the pitch starts high and glides down to me. These two sounds also share a very similar timbre, which communicates to the user that the two actions are related. Any Mac user might also recognize that these are also the same sounds used for sending and receiving messages in iChat – a nice bit of product consistency on Apple’s part.
The power connect sound also uses the rising of pitch to also convey a forward or upward movement. Two ascending notes (C6 to F6) are used to signify your phone is connected with a cable and powering up.
The sound made when your phone is locked and you get a text is different than when you’re already in the Messages app and recieve a text. It’s the most musical sound the iPhone uses, and even though it’s is used in other Apple products – I used to have it associated with iTunes completing a CD rip – the sound itself does convey a little bit of happiness. Without delving too much into musical theory, the three notes played – D4, A4, D5 – follow the simple and happy root - major fifth - octave progression. Text messages can of course carry bad news, but I think that this little ditty primes us to be excited when a text comes in.
As of iOS5, the iPhone can natively post tweets through just about any application. When your tweet succesfully posts, a two note bird call is played. The sound of a bird is obviously used because of Twitter’s whole bird branding thing, which itself is a metaphor for sharing a short bursts of information like a bird’s chirp. So this sound is essentially the literal interpretation of a metaphor, with a tiny bit of brand reinforcement for Twitter sprinkled on top.
All of the iPhone’s UI Sounds: