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Digital Audio. Lesson Objectives After completing this lesson, you will be able to:  Identify the various characteristics of digital audio.  Explain.

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Presentation on theme: "Digital Audio. Lesson Objectives After completing this lesson, you will be able to:  Identify the various characteristics of digital audio.  Explain."— Presentation transcript:

1 Digital Audio

2 Lesson Objectives After completing this lesson, you will be able to:  Identify the various characteristics of digital audio.  Explain the concepts of recording, copying, and converting digital audio.  Identify the features of advanced speech technologies.

3  When you speak, the sound you create is in the analog or wave format.  The sound that you hear is also in analog format.  Computers are basically digital devices. Therefore, it is necessary to convert audio from the analog format to the digital format before using it on a computer. Analog and Digital Audio

4  Digital audio technology allows you to record, edit, and play digital audio files on a computer.  Advanced digital audio technology also lets you communicate with the computer by just speaking. Analog and Digital Audio (cont.)

5 Characteristics of Digital Audio  Digital Audio file can be compressed.  Audio files are generally large.  Compressed audio files save space, allow portability, and are easier to transfer over the Internet.  When you compress audio files, the quality of the audio file is generally affected.

6  Another important characteristic of digital audio is that it can be edited on a computer by using audio editing software.  You can use audio editing software to move sections within an audio file or add effects.  You can also use audio editing software to store an audio file in different formats on the computer. Characteristics of Digital Audio (cont.)

7  Some of the common formats that you need to be familiar with are:  Wave (WAV)  MPEG Audio Layer 3 (MP3)  Windows Media® Audio (WMA) Audio File Formats

8 Wave (WAV)  This format is part of a series of standards for audio and video developed for Microsoft Windows® 95 as a universal sound file format.  It is used to store audio files in the wave audio format.  Audio files stored in this format have good audio quality.  Audio files in this format are larger when compared with other formats.

9 MPEG Audio Layer 3 (MP3)  This format was developed by Motion Picture Expert Group to allow compression of audio and video for digital distribution.  The MP3 format is a popular format that is used to store digital audio files.  MP3 files are generally smaller than WAV files.

10 Windows Media® Audio (WMA) This format was developed by Microsoft and is used to store digital audio files.

11  Digital audio allows streaming of digital audio files.  You can use a streaming audio player or a browser plug- in to play the audio file from the Internet.  The audio file is sent to your computer in a continuous stream. Audio Streaming

12 Recording, Copying, and Converting Digital Audio  The technique of recording and storing audio files in a digital format is called digital recording.  You can then copy the stored audio files to storage devices, such as recordable CDs and DVDs, in various formats, such as WAV and MP3.  You can also convert audio from a CD or a DVD to a different format before you store it on your computer’s hard disk.

13 Copying Audio Hardware  You can copy audio from storage devices, such as a computer’s hard disk, and store it on a recordable CD or DVD.  This process of copying audio to a recordable CD or DVD is referred to as burning.  You need a special hardware device, such as a CD writer or a DVD writer, to copy audio to recordable CDs or DVDs.  A CD writer allows you to copy audio only to recordable CDs whereas most DVD writers allow you to copy audio to recordable CDs and DVDs.

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15  Along with hardware, you also need software to copy audio to a recordable CD or DVD.  You can use the software to create different types of CDs. You can create data CDs, audio CDs, and mixed mode CDs.  Mixed mode CDs contain audio, video, and data files. Copying Audio Software

16 Converting Audio  You can convert audio from a CD or a DVD to a different format before storing it on a computer’s hard disk.  Example:  You can convert your favorite song from a CD to an MP3 file before storing it on the computer.  You can then play the MP3 file by using the digital devices, such as an MP3 player.

17 Converting Audio (cont.)  You must have audio conversion software, such as Microsoft Windows Media Player, installed on your computer to convert audio files.  The software changes the format of the audio and might also compress the audio so that the files take up less space on the hard disk.  You can then transfer these audio files from the computer to a portable medium, such as a PDA or a cell phone.

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19 Speech Recognition and Synthesis  Digital audio technology allows you to interact with the computer by just speaking.  This helps improve productivity and empowers challenged users to expand their ability to use computers.

20 Speech Recognition

21  Speech recognition is a technology that allows you to communicate with a computer by using only your voice to enter text and to issue commands.  To enable speech recognition, you need an audio input device, such as a microphone, a sound card, and speech recognition software that converts human speech into text or commands for the computer.  You can use speech recognition technology to interact with various programs Speech Recognition

22  The speech recognition feature is readily available in Microsoft Office XP applications such as Word.  In Word, you can use the speech recognition feature to dictate words, which are then converted to text.  You can also select menus, toolbars, and dialog box items. Speech Recognition (cont.)

23 Speech Synthesis

24 Speech Synthesis (cont.)  Speech synthesis is a technology that allows the computer to speak to you.  In speech synthesis, the computer communicates to you by converting text to digital audio.  Windows XP has a built-in feature that supports speech synthesis.  To support speech synthesis, your computer must be equipped with a sound card and speakers.  To configure the speech synthesis options on your computer, in Control Panel, double-click Speech.

25 Questions


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