Voice user interface

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A voice-user interface (VUI) makes spoken human interaction with computers possible, using speech recognition to understand spoken commands and questions, and typically text to speech to play a reply. A voice command device (VCD) is a device controlled with a voice user interface.

Voice user interfaces have been added to automobiles, home automation systems, computer operating systems, home appliances like washing machines and microwave ovens, and television remote controls. They are the primary way of interacting with virtual assistants on smartphones and smart speakers. Older automated attendants (which route phone calls to the correct extension) and interactive voice response systems (which conduct more complicated transactions over the phone) can respond to the pressing of keypad buttons via DTMF tones, but those with a full voice user interface allow callers to speak requests and responses without having to press any buttons.

Newer VCDs are speaker-independent, so they can respond to multiple voices, regardless of accent or dialectal influences. They are also capable of responding to several commands at once, separating vocal messages, and providing appropriate feedback, accurately imitating a natural conversation.[1]


A VUI is the interface to any speech application. Controlling a machine by simply talking to it was science fiction only a short time ago. Until recently, this area was considered to be artificial intelligence. However, advances in technologies like text-to-speech, speech-to-text, Natural Language Processing, and cloud services, in general, contributed to the mass adoption of these types of interfaces. The commercial success of voice-only interfaces such as Apple's Siri, Amazon's Alexa and Google Home broadened the concept to the mainstream.[2] VUIs have become more commonplace, and people are taking advantage of the value that these hands-free, eyes-free interfaces provided in many situations.

VUIs need to respond to input reliably, or they will be rejected and often ridiculed by their users. Designing a good VUI requires interdisciplinary talents of computer science, linguistics and human factors psychology – all of which are skills that are expensive and hard to come by. Even with advanced development tools, constructing an effective VUI requires an in-depth understanding of both the tasks to be performed, as well as the target audience that will use the final system. The closer the VUI matches the user's mental model of the task, the easier it will be to use with little or no training, resulting in both higher efficiency and higher user satisfaction.

A VUI designed for the general public should emphasize ease of use and provide a lot of help and guidance for first-time callers. In contrast, a VUI designed for a small group of power users (including field service workers), should focus more on productivity and less on help and guidance. Such applications should streamline the call flows, minimize prompts, eliminate unnecessary iterations and allow elaborate "mixed initiative dialogs", which enable callers to enter several pieces of information in a single utterance and in any order or combination. In short, speech applications have to be carefully crafted for the specific business process that is being automated.

Not all business processes render themselves equally well for speech automation. In general, the more complex the inquiries and transactions are, the more challenging they will be to automate, and the more likely they will be to fail with the general public. In some scenarios, automation is simply not applicable, so live agent assistance is the only option. A legal advice hotline, for example, would be very difficult to automate. On the flip side, speech is perfect for handling quick and routine transactions, like changing the status of a work order, completing a time or expense entry, or transferring funds between accounts.


Early applications for VUI included voice-activated dialing of phones, either directly or through a (typically Bluetooth) headset or vehicle audio system.

In 2007, a CNN business article reported that voice command was over a billion dollar industry and that companies like Google and Apple were trying to create speech recognition features.[3] It has been years since the article was published, and since then the world has witnessed a variety of voice command devices. In addition, Google created a speech recognition engine called Pico TTS and Apple has released Siri. Voice command devices are becoming more widely available, and innovative ways for using the human voice are always being created. For example, Business Week suggests that the future remote controller is going to be the human voice. Currently Xbox Live allows such features and Jobs hinted at such a feature on the new Apple TV.[4]

Voice command software products[edit]

Both Apple Mac and Windows PC provide built in speech recognition features for their latest operating systems.

Microsoft Windows[edit]

Two Microsoft operating systems, Windows 7 and Windows Vista, provide speech recognition capabilities. Microsoft integrated voice commands into their operating systems to provide a mechanism for people who want to limit their use of the mouse and keyboard, but still want to maintain or increase their overall productivity.[5]

Windows Vista[edit]

With Windows Vista voice control, a user may dictate documents and emails in mainstream applications, start and switch between applications, control the operating system, format documents, save documents, edit files, efficiently correct errors, and fill out forms on the Web. The speech recognition software learns automatically every time a user uses it, and speech recognition is available in English (U.S.), English (U.K.), German (Germany), French (France), Spanish (Spain), Japanese, Chinese (Traditional), and Chinese (Simplified). In addition, the software comes with an interactive tutorial, which can be used to train both the user and the speech recognition engine.[6]

Windows 7[edit]

In addition to all the features provided in Windows Vista, Windows 7 provides a wizard for setting up the microphone and a tutorial on how to use the feature.[7]

Mac OS X[edit]

All Mac OS X computers come pre-installed with the speech recognition software. The software is user independent, and it allows for a user to, "navigate menus and enter keyboard shortcuts; speak checkbox names, radio button names, list items, and button names; and open, close, control, and switch among applications."[8] However, the Apple website recommends a user buy a commercial product called Dictate.[8]

Commercial products[edit]

If a user is not satisfied with the built in speech recognition software or a user does not have a built speech recognition software for their OS, then a user may experiment with a commercial product such as DragonNaturallySpeaking for Windows PCs,[9] and Dictate, the name of the same software for Mac OS.[10]

Voice command mobile devices[edit]

Any mobile device running Android OS, Microsoft Windows Phone, iOS 5 or later, or Blackberry OS provides voice command capabilities. In addition to the built speech recognition software for each mobile phone's operating system, a user may download third party voice command applications from each operating system's application store: Apple App store, Google Play, Windows Phone Marketplace (initially Windows Marketplace for Mobile), or BlackBerry App World.

Android OS[edit]

Google has developed an open source operating system called Android, which allows a user to perform voice commands such as: send text messages, listen to music, get directions, call businesses, call contacts, send email, view a map, go to websites, write a note, and search Google.[11] The speech recognition software is available for all devices since Android 2.2 "Froyo", but the settings must be set to English.[11] Google allows for the user to change the language, and the user is prompted when he or she first uses the speech recognition feature if he or she would like their voice data to be attached to their Google account. If a user decides to opt into this service, it allows Google to train the software to the user's voice.[12]

Google introduced the Google Assistant with Android 7.0 "Nougat". It is much more advanced than the older version.

Amazon.com has the Echo that uses Amazon's custom version of Android to provide a voice interface.

Microsoft Windows[edit]

Windows Phone is Microsoft's mobile device's operating system. On Windows Phone 7.5, the speech app is user independent and can be used to: call someone from your contact list, call any phone number, redial the last number, send a text message, call your voice mail, open an application, read appointments, query phone status, and search the web.[13][14] In addition, speech can also be used during a phone call, and the following actions are possible during a phone call: press a number, turn the speaker phone on, or call someone, which puts the current call on hold.[14]

Windows 10 introduces Cortana, a voice control system that replaces the formerly used voice control on Windows phones.


Apple added Voice Control to its family of iOS devices as a new feature of iPhone OS 3. The iPhone 4S, iPad 3, iPad Mini 1G, iPad Air, iPad Pro 1G, iPod Touch 5G and later, all come with a more advanced voice assistant called Siri. Voice Control can still be enabled through the Settings menu of newer devices. Siri is a user independent built-in speech recognition feature that allows a user to issue voice commands. With the assistance of Siri a user may issue commands like, send a text message, check the weather, set a reminder, find information, schedule meetings, send an email, find a contact, set an alarm, get directions, track your stocks, set a timer, and ask for examples of sample voice command queries.[15] In addition, Siri works with Bluetooth and wired headphones.[16]

Amazon Alexa[edit]

In 2014 Amazon introduced the Alexa smart home device. Its main purpose was just a smart speaker, that allowed the consumer to control the device with their voice. Eventually, it turned into a novelty device that had the ability to control home appliance with voice. Now almost all the appliances are controllable with Alexa, including light bulbs and temperature. By allowing voice control Alexa can connect to smart home technology allowing you to lock your house, control the temperature, and activate various devices. This form of A.I allows for someone to simply ask it a question, and in response the Alexa searches for, finds, and recites the answer back to you.[17]

Speech recognition in cars[edit]

As car technology improves, more features will be added to cars and these features will most likely distract a driver. Voice commands for cars, according to CNET, should allow a driver to issue commands and not be distracted. CNET states that Nuance is suggesting that in the future they will create a software that resembles Siri, but for cars.[18] Most speech recognition software on the market today only have about 50 to 60 voice commands, but Ford Sync has 10,000.[18] However, CNET suggest that even 10,000 voice commands is not sufficient given the complexity and the variety of tasks a user may want to do while driving.[18] Voice command for cars is different from voice command for mobile phones and for computers because a driver may use the feature to look for nearby restaurants, look for gas, driving directions, road conditions, and the location of the nearest hotel.[18] Currently, technology allows a driver to issue voice commands on both a portable GPS like a Garmin and a car manufacturer navigation system.[19]

List of Voice Command Systems Provided By Motor Manufacturers:

Future uses[edit]

Pocket-size devices, such as PDAs or mobile phones, currently rely on small buttons for user input. These are either built into the device or are part of a touch-screen interface, such as that of the Apple iPod Touch and iPhone Siri Application. Extensive button-pressing on devices with such small buttons can be tedious and inaccurate, so an easy-to-use, accurate, and reliable VUI would potentially be a major breakthrough in the ease of their use. Nonetheless, such a VUI would also benefit users of laptop- and desktop-sized computers, as well, as it would solve numerous problems currently associated with keyboard and mouse use, including repetitive-strain injuries such as carpal tunnel syndrome and slow typing speed on the part of inexperienced keyboard users. Moreover, keyboard use typically entails either sitting or standing stationary in front of the connected display; by contrast, a VUI would free the user to be far more mobile, as speech input eliminates the need to look at a keyboard.

Such developments could literally change the face of current machines and have far-reaching implications on how users interact with them. Hand-held devices would be designed with larger, easier-to-view screens, as no keyboard would be required. Touch-screen devices would no longer need to split the display between content and an on-screen keyboard, thus providing full-screen viewing of the content. Laptop computers could essentially be cut in half in terms of size, as the keyboard half would be eliminated and all internal components would be integrated behind the display, effectively resulting in a simple tablet computer. Desktop computers would consist of a CPU and screen, saving desktop space otherwise occupied by the keyboard and eliminating sliding keyboard rests built under the desk's surface. Television remote controls and keypads on dozens of other devices, from microwave ovens to photocopiers, could also be eliminated.

Numerous challenges would have to be overcome, however, for such developments to occur. First, the VUI would have to be sophisticated enough to distinguish between input, such as commands, and background conversation; otherwise, false input would be registered and the connected device would behave erratically. A standard prompt, such as the famous "Computer!" call by characters in science fiction TV shows and films such as Star Trek, could activate the VUI and prepare it to receive further input by the same speaker. Conceivably, the VUI could also include a human-like representation: a voice or even an on-screen character, for instance, that responds back (e.g., "Yes, Vamshi?") and continues to communicate back and forth with the user in order to clarify the input received and ensure accuracy.

Second, the VUI would have to work in concert with highly sophisticated software in order to accurately process and find/retrieve information or carry out an action as per the particular user's preferences. For instance, if Samantha prefers information from a particular newspaper, and if she prefers that the information be summarized in point-form, she might say, "Computer, find me some information about the flooding in southern China last night"; in response, the VUI that is familiar with her preferences would "find" facts about "flooding" in "southern China" from that source, convert it into point-form, and deliver it to her on screen and/or in voice form, complete with a citation. Therefore, accurate speech-recognition software, along with some degree of artificial intelligence on the part of the machine associated with the VUI, would be required.

See also[edit]


  1. ^ "Washing Machine Voice Control". Appliance Magazine.
  2. ^ Tank, Nikita. "Voice User Interface (VUI) – A Definition". Botsociety Blog.
  3. ^ Borzo, Jeanette (8 February 2007). "Now You're Talking". CNN Money. Retrieved 25 April 2012.
  4. ^ "Voice Control, the End of the TV Remote?". Business Week. Retrieved 1 May 2012.
  5. ^ "Windows Vista Built In Speech". Windows Vista. Retrieved 25 April 2012.
  6. ^ "Speech Operation On Vista". Microsoft.
  7. ^ "Speech Recognition Set Up". Microsoft.
  8. ^ a b "Physical and Motor Skills". Apple.
  9. ^ "DragonNaturallySpeaking PC". Nuance.
  10. ^ "DragonNaturallySpeaking Mac". Nuance.
  11. ^ a b "Voice Actions". Google.
  12. ^ "Google Voice Search For Android Can Now Be "Trained" To Your Voice". Retrieved 24 April 2012.
  13. ^ "Using Voice Command". Microsoft. Retrieved 24 April 2012.
  14. ^ a b "Using Voice Commands". Microsoft. Retrieved 27 April 2012.
  15. ^ "Siri, The iPhone 3GS & 4, iPod 3 & 4, have voice control like an express Siri, it plays music, pauses music, suffle, Facetime, and calling Features". Apple. Retrieved 27 April 2012.
  16. ^ "Siri FAQ". Apple.
  17. ^ https://www.businessinsider.com/amazon-echo-and-alexa-history-from-speaker-to-smart-home-hub-2017-5
  18. ^ a b c d "Siri Like Voice". CNET.
  19. ^ "Portable GPS With Voice". CNET.

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