➢ Any sound-- music, voice, narration ➢ An important element in multimedia. ➢ Without sound, the presentation will be dull.

1. CHAPTER – 5
Audio
Amir Ibrahim
Nov-2021

2. ●
What is Audio?
●
Types of Audio
●
Principles of Digitization
●
Purpose of Audio
●
The Role of Audio
●
Mono vs. Stereo
●
Audio File Format
●
Important Terms
●
Audio editing softwares
Topics

3. ➢ Any sound-- music, voice, narration
➢ An important element in multimedia.
➢ Without sound, presentation will be dull.
Audio

4. Types of Audio

5. ➢ The sound that we hear everyday is in the form of analog.
➢ A form of signals that moves in a continuous wave.
➢ Sound is recorded over a microphone = analog sound.
➢ This kind of sound or analog signals cannot be transmitted through a
computer.
ANALOG AUDIO

6. Wave Characteristics
➢ Frequency:(Pitch) Represents the
number of periods in a second and is
measured in hertz (Hz) or cycles per
second.
➢ Human hearing frequency range: 20Hz
to 20kHz (audio)
➢ Amplitude: The measure of
displacement of the air pressure wave
from its mean. Related to but not the
same as loudness
ANALOG AUDIO
Time
Amplitude
One Period
Air
Pressure
One particular frequency component

7. ➢ Computer recognizes sound in digital format.
➢ Computer will process data into electronic form and not from the physical
movement in the air.
➢ The sound used in multimedia applications are in digital form.
➢ Comprise of the binary code is represented by 0 and 1.
➢ When the analogue wave enters the computer, it will be digitized or in
technical term, has been sampled.
DIGITAL AUDIO

8. ➢ Sampling: Divide the horizontal axis (time) into discrete pieces. (a)
➢ Quantization: Divide the vertical axis (signal strength - voltage) into
pieces. (b)
➢ For example, 8-bit quantization divides the vertical axis into 256 levels. 16
bit gives you 65536 levels.
➢ Lower the quantization, lower the quality of the sound.
Principles of Digitization
(a) (b)

9. Principles of Digitization
9 Li & Drew
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Sampling 3-bit quantization
➢ Sampling rate: Number of
samples per second
(measured in Hz)
➢ E.g., CD standard audio
uses a sampling rate of
44,100 Hz (44100
samples per second)
➢ 3-bit quantization gives 8
possible sample values
➢ E.g., CD standard audio
uses 16-bit quantization
giving 65536 values.

10. ➢ Increases the multimedia attraction. It adds excitement.
➢ more real and memorable.
➢ Can capture attention.
➢ as a guide for the users.
➢ to enhance the interest while maintaining the attention.
➢ to attract the users
➢ to influence user’s emotional and thoughts
➢ to increase the understanding of complex contents through audio
explanation
Purpose of Audio

11. ➢ Warnings and reminders.
➢ Background Music.
➢ Sound effects.
➢ Narration
➢ Data that is related to sound
The Role of Audio

12. Mono vs. Stereo

13. Mono vs. Stereo

14. Mono vs. Stereo

15. ➢ Sound or music can be recorded in a variety of formats.
➢ Most of these audio file formats involve compressing the audio files.
➢ Types of File Format:

.aiff

.au

.wav

.midi

.mp3
Audio File Format

16. ➢ MP3 file is the sound part of MPEG files.
➢ Allows various sampling rates and bit rates.
➢ Most popular sound format for music - High quality and good
compression(Small file size).
➢ Popular for sound transmission on the Internet.
➢ Capable of storing additional textual information such as the subject,
artist's name and comments.
MP3 (Motion Picture Expert Group Layer 3 format)

17. ➢ This audio format is developed by IBM and Microsoft.
➢ The main and popular audio format in the Microsoft Windows operating
system environment.
➢ Can supported by all computers running Windows and by all the most
web browser (except Google Chrome)
wav(Windows Audio Waveform)

18. ➢ Is a format audio for electronic music device like synthesizer and PC
sound card.
➢ Its doesn't contain sound, but digital music instruction (notes) that can
be played by electronic device (like PC's sound card)
➢ MIDI files are small
➢ MIDI is supported by all the most popular web browser.
MIDI (Musical Instrument Digital Interface)

19. ➢ Is a audio format file standard used for storing sound data for PC and
other electronic audio device.
➢ Most commonly used on Apple computer system.
➢ AIFF files generally end with .AIF or .IEF extension
➢ Doesn't support data compression – tend to large.
AIFF (audio interchange file format)

20. ➢ The real audio format was developed for the Internet by real media.
➢ The format file for real audio are .rm and .ram
➢ Its support video format.
➢ Allows streaming of audio with low bandwidth.
RealAudio (.rm / .ram)

21. ➢ The real audio format was developed for the Internet by real media.
➢ The format file for real audio are .rm and .ram
➢ Its support video format.
➢ Allows streaming of audio with low bandwidth.
RealAudio (.rm / .ram)

22. ➢ Amplitude (loudness) : The amplitude of a sound wave is the measure
of the height of the wave.
➢ Clipping : is a form of waveform distortion that occurs when an
amplifier is over-driven and attempts to deliver an output voltage or
current beyond its maximum capability.
Important Terms

23. ➢ Tempo : The speed of music or any sequence of sounds.
➢ Pitch : tells us how shrill or deep the sound is . of a sound depends on
the frequency while loudness of a sound depends on the amplitude of
sound waves.
Important Terms

24. ➢ Audacity – The best free audio editing software.
➢ Adobe Audition – The best music editing software.
➢ FL Studio – The best for electronic music production.
➢ Sound Forge – The best music editing software for Windows users.
➢ Avid Pro Tools – The best professional audio editing software.
➢ Logic Pro X – The best music editing app for Mac.
Audio editing softwares

25. End of chapter - 5
Nov - 2021