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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 a.m.: a deafening shrill begins. For five earsplitting seconds the power plant steam whistle at the University of Kansas sounds. The sound is 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 hour of class time.

According to the student newspaper The Daily Kansan, the whistle was not only used to replace the untimely and inconsistent ringing of bells with a standard schedule of marked time, but 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, too, was one of those students 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. It was so unique that it was never misunderstood, and is so reliable that it is always trusted.

The Importance of Audition

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

Figure 12-1. Control of volume level is usually still performed by hardware keys due to its importance. This makes it an interesting control as it is always pseudomodal. The user enters the mode by using the keys, which loads a screen, layer, or other widget to indicate the volume change. Related controls, silence and vibrate, are associated with this mode as well.

Auditory Classifications

Audible sounds and notifications have become so commonplace today that we have learned to understand their meaning and quickly decide whether we need to attend to them in a particular context.


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

Alerts and Notifications

Alerts are not used to signal immediate action due to safety. Instead, they are used to capture your attention to indicate that an action may be required or to 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 their contextual meaning. Examples of alert and notification sounds include:

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. Mobile error tones are often buzzers to indicate:

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. Examples of voice notifications include:

Feedback Tones

Feedback tones occur immediately after you press a key or button such as a dialer. They confirm that an action has been completed. These may appear as clicks or single tones. Feedback tones can occur when you:

Audio Guidelines in the Mobile Space

Figure 12-2. Voice inputs can help users in situations where visibility is limited or nonexistent, but they have to be part of a complete voice UI. Don’t just perform one or two steps of a process and then require the user to read and provide feedback on the screen.

Signal-to-Noise Ratio Guidelines

People will use their mobile devices in any environment and context. In many situations, they will rely on the device’s voice input and output functions during use. See Figure 12-2. But, whether the person is inside or outside, her ability to hear certain speech decibels apart from other external noises can be quite challenging. Here are some guidelines to follow when designing mobile devices that rely on speech output and input:

Speech Recognition Guidelines

In addition to the signal-to-noise guidelines in the preceding section, you must under- stand how users recognize speech. The following guidelines will assist you when designing Voice Notifications:

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

Accessibility Resources

Here are useful resources on audio accessibility. Included is information on types of as- sistance technologies companies are using in mobile devices today.

The Importance of Vibration

Figure 12-3. Vibrate on most devices is coarse, and is provided by a simple motor with an off-center weight. Here, it is the silver cylinder between the camera and the external screen; the motor is mostly covered by a ribbon cable. It is mounted into a rubber casing, to avoid vibrating the phone to pieces, but this also reduces the fidelity of specific vibrate patterns, if you were to try to use it for that purpose. The figure on the right shows the motor assembly on its own.

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 the largest organ in our body is our skin, which 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.

When designing mobile devices that incorporate haptics, be familiar with the following information:

Common Haptic Outputs on Mobile Devices

Many mobile devices today use haptics to communicate a direct response to an action:

Haptic Concerns

Using haptics appropriately is a great way to provide users with additional sensory feedback. However, you still need to be aware that:

Patterns for Audio & Vibration

Using audio and vibration control appropriately provides users with methods to engage with the device other than relying on their visual sense. These controls can be very effec- tive when users may be at a distance from their device, or are unable to directly look at the display but require alerts, feedback, or notifications. In other situations, a visually im- paired user may require these controls because they provide accessibility. We will discuss the following patterns in this chapter:


Voice Input

Voice Readback

Voice Notifications

Haptic Output

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