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Sound - PowerPoint PPT Presentation

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Sound . By John Sullivan For Multimedia I. Sound Contents. Sound Digital Sound Multimedia The Web Audio Software Creating Music CDs. Sound. How you use the power of sound can make the difference between an ordinary multimedia presentation and a professionally spectacular one.

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By John Sullivan


Multimedia I

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Sound Contents

  • Sound

  • Digital Sound

  • Multimedia

  • The Web

  • Audio Software

  • Creating Music CDs

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How you use the power of sound can make the difference between an ordinary multimedia presentation and a professionally spectacular one.

Sound is perhaps the most sensuous element in multimedia.

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Sound continued

Renowned Japanese film director, Akira Kurosawa, famous for his work in a visual medium, nonetheless has this to say about he medium “The most exciting moment is the moment when I add sound ….[Then] I tremble” (Alten, 1994, p.4.).

A multimedia developer should be aware of sound at all times in order to successfully accomplish the information-conveying and aesthetic goals of a multimedia production (Tannenbaum, 1999).

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Sound 3

For convenience, sound may be classified in three categories:

  • music

  • speech

  • other sounds

    Example: Laurie Smith Project 1

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The Power of Sound

Sounds vary in sound pressure level (amplitude) and in frequency or pitch. Amplitude refers to loudness of sound.

Acoustics is the branch of physics that studies sound.

  • Sound pressure levels (loudness & volume) are measure in decibels (dB)

  • Decibels is a measurement on a logarithmic scale. When you make sound 100 times more intense, the increase in dB is not hundredfold, but only 20 dB.

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When something vibrates in the air by moving back and forth

(cone of a loudspeaker), it creates waves of pressure.


These waves spread like the

ripples from a pebble tossed into

a still pool and when they reach

your eardrums, you experience the

changes of pressure, or

vibrations, as sound.

The ripples propagate at about 750 mph, or Mach 1

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Sound Frequency

Range of frequencies from the low end of the spectrum (20hz to 40hz) to a high end of (20 Kilohertz)

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Analog to Digital

  • Digitization is the process involved in transforming an analog signal into a digital one.

  • Two steps

    • First analog must be sampled

    • Second is quantization

      • Quantization

      • Code- Word

  • Why?

    • Analog transformations introduce distortions and noise

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Digital Sound

  • With digital sound you can edit, process, and retrieve sound data with more accuracy than analog.

    • Sampling rate - measured in samples per second

    • Sample size is the amount of information stored

    • The three most used sampling frequencies

      • Studio Quality – 88 kHz, 16 bit

      • CD Quality – 44.1 kHz, 22.05 kHz, 8 or 16 bit

      • Radio Quality – 22 kHz, 8 bit, mono

      • Telephone Quality – 11 kHz, 8 bit, mono

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Sound Waves & Sampling








Higher sampling rate

Low sampling rate

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Sampling and File Size

For Mono at the same sampling rate divide by 2

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Audio Interchange File Format - AIFF, AIF

Musical Instrument Digital Interface (MID, MDI, MFF)

is an internationally accepted file format to store MIDI data

Resource Interchange File Format (RIFF)

developed by Microsoft and contains digital and MIDI


RA – Real Audio

Sound (SND) - apple

Roll (ROL) -developed by AdLib, Inc. for their sound cards

Midi-like data and Yamaha FM synthesizer info

Wave (Wav) - windows by Microsoft as subset of RIFF

Sun Audio (AU) - Sun Microsystems

Voice (V0C) Sound Blaster

File Formats

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Motion Picture Expert Group (MPEG)

  • MPEG – 1: intended for the storage of VCR-quality audio video sequences on CD-ROMs at 1.2 Mbps

    • MP3 music files are MPEG Audio Layer IIIstandard that is a digital audio compression algorithm that achieves a compression factor of about twelve while preserving sound quality. It does this by optimizing the compression according to the range of sound that people can actually hear.

  • MPEG – 2: targets studio quality television HDTV and multiple CD-quality audio channels at 4 to 6 Mbps

  • MPEG – 4: targets videoconferencing

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MIDI Versus Digital Audio

  • Musical Instrument Digital Interface is a communications standard developed in the early 1980’s for electronic musical instruments.

  • MIDI data is a musical score not digitized sound

  • MIDI files are:

    • 200 to 1000 times smaller than CD-quality digital audio files.

    • Good for Web pages

    • In some cases, MIDI files sound better than digital audio files

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Understanding MIDI

  • Controller - Musical instrument

    • 127 different instruments, 7 types of piano, 8 types of guitar, French horn, and 47 percussion sounds.

  • Synthesizer

  • Because MIDI systems do not record the actual sounds in the digital file, the resulting file is smaller. For example, on average 1 min of MIDI requires 30K whereas it would be 10.5 Meg for the same duration of CD-Quality digital audio (16 bit, 44 Khz, stereo)

  • Consistency in audio quality

  • Compatibility

  • Less processor speed

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Choosing Between MIDI and Digital Audio

  • USE MIDI when

    • Digital audio won’t work because of space RAM, HD, CPU

    • You do not need spoken dialog

    • You have complete control of playback hardware

    • You have high-quality MIDI sound source

  • Use digital audio when

    • You have resources

    • You need spoken dialog

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The Advantage of Digital Sound Systems

  • Advantages

    • No hiss

    • No loss of information

    • Easy access to recorded data

    • Synchronize sound with a high degree of accuracy.

  • Disadvantages

    • Sound accurate only if the MIDI playback device is identical to the device used in production

    • Cannot easily be used to play back spoken dialog.

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You Need to Know

  • How to make sounds

  • How to record and edit sounds

  • How to incorporate sounds into your work

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Editing Audio

  • Trimming - Do not just end or begin anywhere

  • Volume Adjustments

  • Format conversion

  • Fade-ins and fade-outs - enveloping

  • Resampling or down-sampling

  • Time Stretching

  • Reversing Sounds

  • Mixing audio - capability of mixing two or more audio files.

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Stravinsky’s Rite of Spring

  • Music, the organized movement of sounds through a continuum of time. Music plays a role in all societies, and it exists in a large number of styles, each characteristic of a geographical region or a historical era.

  • Music has long been a significant part of religious ritual and pageants.

  • The purpose of the inclusion of music, as with any other medium, is to enhance the effectiveness of the communication.

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Why Use Sound in a Multimedia Presentation?

  • Incorporate ambient sounds to reinforce your message

  • Add music to set the mood

  • Use sound to catch the interest (wake up) of the audience

  • Include narration effectively in training and educational applications

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Sound and the Web

  • Used for

    • set mood

    • background sound

    • to draw attention - as message (newspaper dropping)

    • hover button sound

    • speech

    • Entertainment

  • Types of Sound Files

    • .au

    • .wav

    • .midi

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Background Audio on the Web

Internet Explorer bgsound

The <bgsound> Tag

<bgsound src=“audio/welcome.wav”>

<bgsound src="Audio/w13mx11x8e.wav" loop=infinite>


<bgsound src="caribian.mid" loop=2>


Netscape embed

<embed src=music.wav hidden autostart true loop=true>


<embed src=music.wav>

Might present audio control panel

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Music Software

  • With Windows

    • Sound Recorder

  • With Sound Card

    • Turtle Beach

      Montego Bay

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  • Most developers play it safe by always making their own custom music from scratch in a sound studio, or with synthesizers

  • Others just take a risk and break the law

  • Educational Use

  • Fair Use

    • 10% or 30 seconds, which ever is shorter

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Music Galore:

THX – sound Lucas Films

PropellerHeads, Take California DecksandDrumandRockandRoll, Dreamworks Records, 1998

Microsoft Encarta, 1995

Jean Michel Jarre, First Rendez-vous, Renez-vous, Dreyfus, 1986

Laurie Smith, Project 1, 1999

Michelle Bzenk Project 3, 2000



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The End


John Sullivan