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