Differences between revisions 7 and 8
Revision 7 as of 2011-05-01 10:29:06
Size: 10404
Editor: localhost
Comment:
Revision 8 as of 2011-05-01 10:30:12
Size: 10400
Editor: localhost
Comment:
Deletions are marked like this. Additions are marked like this.
Line 91: Line 91:
=== Common haptic outputs on mobile devices === === Common Haptic Outputs on Mobile Devices ===
Line 110: Line 110:

The Big Tooter

High atop Mount Oread, in the picturesque city of Lawrence, Kansas, stands a whistle. A whistle with quite a history composed of tradition, controversy, and headache that started about a hundred years ago. The whistle is known as the “Big Tooter”.

March 25, 1912, 9:50 am. A deafening shrill begins. For five earsplitting seconds, the power plant steam whistle at the University of Kansas sounds. A sound so loud, it can be heard from one side of the city to the other. It’s the first time the whistle is used to signal the end of each hourly class time.

According to the student newspaper, The Daily Kansan, the whistle was not only used to replace untimely and inconsistent ringing of bells with a standard schedule of marked time, it was also used to remind professors to end their lectures immediately. Prior to the whistle, too often, professors would keep students past the 55 minutes of class time, causing them to be late for their next class. With the new sound system in place, even the Chancellor had something to say.

  • “If the instructor isn’t through when the whistle blows,” said KU Chancellor Frank Strong to the student body, “get up and go.”

The Big Tooter Today

For the past 100 years, the Big Tooter has been the deafening reminder to faculty and students about punctuality and when to cover their ears. I can say I was one of those students too, who would purposely alter my walk to class to avoid that sound at its loudest range. But, despite the fact that the steam whistle was excruciatingly loud, it served its purpose as an audio alert, so unique, it was never misunderstood.

The Importance of Audition

From the example above, we see that people can benefit from specific sounds that are associated with contextual meaning. Using audition in the mobile space can take advantage of this very important concept for the following reasons:

  • Our mobile devices may be placed and used anywhere. In these constantly changing environmental contexts, the user is surrounded by external stimuli that are constant fighting with their attention capacity.
  • The device may be out of our range of site, but not our auditory sensitivity levels.
  • Using audition together with other sensory cues can help reinforce and strengthen their understanding of the interactive context.
  • The user may have impaired vision, thus requiring additional auditory feedback to assist them their needs.
  • The user may require auditory cues to refocus their attention on something needing immediate action.

Auditory Classifications

Audible sounds and notifications have become so common-place today that we have learned to understand their meaning and quickly decide whether or not we need to attend to them in a particular context.

Warnings

Audible warnings indicate a presence of danger and action is required for one’s safety. These sounds have loud decibels (up to 130 dB) and some use dual frequencies to quickly distinguish themselves amongst all of the external noise that may be occurring at that time. Most often these warning are used with visual outputs as well.

  • Railroad train crossings
  • Emergency vehicle sirens
  • Fire alarms
  • Tornado sirens
  • Emergency broadcast interrupts
  • Fog horns
  • Vehicle horns

Alerts and Notifications

Alerts are not used to signal immediate action due to safety. Instead they are used to capture your attention to indicate an action may be required or let you know an action has completed. Alerts can be a single sound, one that is repetitive over a period of time and can change in frequency.

Mobile alerts are quite common. They must be distinguishable and never occur at the same time as others. When appropriate, use visual indicators to reinforce their meanings. Use a limited number of alert sounds, otherwise the user will not retain its contextual meaning.

  • A metal detector sounding when combing the beach.
  • A sound of doorbell
  • An arrived elevator
  • A beeping crosswalk indicator.
  • The sound of a device being turned on or off.
  • A voicemail received on your mobile device
  • A low battery level notification.
  • A sound to indicate a meeting reminder.

Error tones

Error tones are a form of immediate or slightly delayed feedback based on user input. These errors must occur in the current context. Examples of mobile error tones are often buzzers to indicate:

  • Entering the wrong choice or key during input.
  • A failure of loading or synching.

Voice Notifications

Voice notifications can be used as reminders when you are not holding your device, as well as notifications of incorrect and undetectable input through voice, touch or keypad. Use syntax that makes it clear what is being communicated. Keep the voice notification messages short and simple.

  • Reminder to take your medication
  • Turn by turn directions
  • A notification to repeat your last input because it wasn’t understood by the system.

Feedback Tones

Feedback tones occur immediate after pressing a key or button such as the dialer. They confirm that an action has been completed. These may appear as clicks or single tones.

  • Entering phone numbers on the dialer.
  • Entering characters on the keyboard.
  • Holding down a key for an extended time to access an application like voicemail.
  • Pressing a button to submit user generated data.
  • Selecting incremental data on a tape or slider selector.

Audio Guidelines to Consider in the Mobile Space

Signal to Noise Ratio Guidelines

  • Signal to Noise Ratio (S/N) is calculated by subtracting the noise decibels from the speech decibels.
  • To successfully communicate voice messages in background noise, the speech level should exceed the noise level by at least 6 decibels (dB) (Bailey, 1996).
  • A user’s audio recall is enhanced when grammatical pauses are inserted in synthetic speech (Nooteboom, 1983).
  • Synthetic speech is less intelligible in the presence of background noise at a 10 dB S/N ratio.
  • When the noise level is +12dB to the signal level, the consonants m,n, d,g, b, v, and z are confused with one another

When the noise level is +18dB to the signal level, all consonants are confused with one another. (Kryter, 1972).

Speech Recognition Guidelines

  • Words in context are recognized more when they are used in a sentence rather than being isolated especially during background noise.
  • Word recognition increases when using common and familiar words to the user.
  • Word recognition will increases if the user is given prior knowledge of the sentence topic.

Audio accessibility in the mobile space

When designing for mobile as with any device, always consider your users, their needs, and their abilities. Many people who use mobile devices experience visual impairments. We need to create an enriching experience for them as well.

Recently, companies are addressing accessibility needs as standard functions in mobile devices. Before this, visually impaired users were forced to purchase supplemental screen reader software that work on only a few compatible devices and browsers. These are quite expensive starting around $200-$500.

Accessibility Resources

  • Apple has integrated VoiceOver into their iPhone, iPod, iPad devices. For more information on Apple’s accessibility commitment, visit their site at http://www.apple.com/accessibility.

  • Companies such as Code Factory have created Mobile Speak, a screen reader for multi OS devices. See their site at http://www.codefactory.es/en.

  • For additional information on accessibility and technology assistance for the visual impaired, I recommend viewing the American Foundation for the Blind’s website. www.afb.org.

The Importance of Vibration

Depending on our users needs, their sensory limitations, and the environment in which mobile is used, vibration feedback can provide another powerful sensation to communicate meaning.

Since our largest organ in our body is the skin that responds to pressure, we can sense vibrations anywhere on our body. Whether we are holding our device in our hands, or carrying it in our pocket, we can feel the haptic output our devices produce.

  • Haptic sense can provide support when the visual and auditory channels are overloaded.
  • The touch sense is able to respond to stimuli every bit as quickly as the auditory sense and even faster than the visual sense (Bailey, 1996).
  • In high noise level areas or where visual and auditory detection is limited, haptics can provide an advantage.

Common Haptic Outputs on Mobile Devices

  • A localized vibration on key entry or button push.
  • A ringtone set to vibrate.
  • A device vibration to indicate an in-application response, such as playing an interactive game i.e, the phone might vibrate when a fish is caught, or when the car your steering accidently crashes.

Haptic Concerns

  • Using haptics can quicken the process of draining battery life. Provide the option to turn haptic feedback on and off.
  • Use haptics when appropriate. Too much might reduce the user’s attention to the stimuli and ignore the response.

Patterns for Audio & Vibration

Using Audio & Vibration control appropriately provides users methods to engage with the device other than relying on their visual sense. The following patterns in the chapter will be discussed.

  • Tones– Non-verbal auditory tones must be used to provide feedback or alert users to conditions or events, but must not becoming confusing, lost in the background or so frequent that critical alerts are disregarded.

  • Voice Input – A method must be provided to control some or all of the functions of the mobile device, or provide text input, without handling the device.

  • Voice Readback – Mobile devices must be able to read text displayed on the screen, so it can be accessed and understood by users who cannot use or read the screen.

  • Voice Notifications – Provides users conditions, alarms, alerts and other contextually-relevant or timebound content without reading the device screen.

  • Haptic Output – Vibrating alerts and tactile feedback should be provided to help assure perception and emphasize the nature of UI mechanisms.

Audio and Vibration (last edited 2011-12-13 19:39:41 by shoobe01)