Audio

     

 

 Audio is another very important component of multimedia, because in many cases sound can substantially reinforce our understanding of information presented in other ways, and in some cases sound is the only way to provide the desired information. In the multimedia application meant for educating small children, voice explanation can be added to the animation clip for describing what is being shown, and pointing out what to look for that makes a horse's gallop different from a horse's walk. Similarly an animation clip can show the horse neighing and neighing sound can be added to effectively convey the type of sound horses make.

Analog and Digital Audio: 

Audio information travels in natural medium in the form of sound waves, which are analog in nature. For the computer to be able to understand audio information, sound waves must be converted from analog to digital form. Transducer is a device capable of changing signals from one form to another. For example of a transducer, which convertssound waves into electrical signals. Conversely loudspeaker is an example of a transducer, which converts electrical signals into sound waves.

Information can be represented as analog signals or digit signals. Analog signals exhibit a continuous tone of smooth fluctuations, while digital signals are composed of discrete values represented by numbers. The transformation between analog and digital signals is achieved be A/D (Analog-to-Digital) conversion and D/A (Digital-to-Analog) conversion. A/D conversion transforms an analog input (such an voltage) into a series of numeric representation by digitization. D/A conversion is the reverse process, which transforms a sequence of discrete numbers back into continuous analog signal.

Hardware Requirement for Audio:

da Computer audio generally involves the following hardware devices:

1. A sound board (or sound card), which is equipped with A/D and D/A converts.

2. Some type of input device (such as microphones) is used for audio input to record a human voice or music or any type of sound in a computer. The A/D converter of the soundboard takes care of digitizing the input sound.

3. Some type of output device (such as speakers or headphones) is used for audio output to listen to a record sound. The D/A converter of the soundboard takes care of converting the sound from its digital to analog form.

4. Synthesized sound can also be generated on a computer by using keyboard (as interaction device) and sound sequencer software.

5. Sound editors are used to cut and paste sound sequences to add special effects and to create new sound sequence from existing sound sequence.

6. Audio mixers are used to combine multiple channels of sound with controls like synchronization points.

Software Requirement for Audio:

1.Audio clips: This is a library of audio clips (pre-made sound effects, music and narration) from which one can select and directly import an audio clip and use it in a multimedia application.

2. Audio file importing: The task of creating a multimedia application incorporating audio can often be greatly simplified, if the application software can import audio files in some standard formats.

3. Software support for high quality sound: If a multimedia application uses very high quality audio, to reproduce the sound effectively, it is important to have not only the necessary hardware, but also software support for both recording and playback of high quality audio.

4. Recording and Playback capability: It allows the user to control the recording and playback of an audio sequence. For example, it provides the user with option to "pause" and "replay" the sound sequence.

5. Text-to-speech conversion software: It is used to convert written text into corresponding sound.

6. Speech-to-text conversion software: It is used to convert speech into corresponding text.

7. Voice reorganization software: It is used to identify the speaker of a given voice by matching the voice with a set of voice stored in a database along with the details of the speaker of each voice.