1.
Chapter 5
Sound
9/20/2018

2. Overview Introduction to sound. Multimedia system sound.
Overview
Introduction to sound.
Multimedia system sound.
Digital audio.
MIDI audio.
Audio file formats.

3. Overview MIDI versus digital audio.
Overview
MIDI versus digital audio.
Adding sound to multimedia project.
Professional sound.
Production tips.

4.
Power of Sound
Vibrations in the air create waves of pressure that are perceived as sound.
Sound waves vary in sound pressure level (amplitude) and in frequency.
‘Acoustics’ is the branch of physics that studies sound.
Sound pressure levels (loudness or volume) are measured in decibels (dB).
Humans hear sound over a very broad range

5. Sound Sound is energy, caused by molecules vibrating
Sound
Sound is energy, caused by molecules vibrating
Too much volume can permanently damage your ears and hearing
The perception of loudness depend on the frequency

6. Using Sound in Multimedia
Using Sound in Multimedia
You need to know
How to make sounds
How to record and edit sounds on the computer
How to incorporate sounds into your multimedia project

7. Multimedia System Sounds
Multimedia System Sounds
System sounds are assigned to various system events such as startup and warnings, among others.
Macintosh provides several system sound options such as glass, indigo, laugh.
In Windows, available system sounds include start.wav, chimes.wav, and chord.wav.
Multimedia sound is either digitally recorded audio or MIDI (Musical Instrumental Digital Interface) music.

8. Multimedia System Sounds
Multimedia System Sounds
Windows system sounds are .WAV files in the Windows\Media directory
MS Office includes additional sounds
You can add your own sounds by including them in the Windows\Media directory and selecting them from the Sound Control Panel

9.
MIDI vs. Digital Audio
MIDI ( Musical Instrument Digital Interface) is a communications standard developed in the 1980’s for electronic instruments and computers.
It allows instruments from different manufacturers to communicate.

10.
MIDI vs. Digital Audio
MIDI data is NOT digitized sound- it is music stored in numeric format
Digital audio is a recording, which depend on your sound system
MIDI is a score and depends on both the quality of the instruments and the sound system
Quality depends on end user’s device rather than on the MIDI device and is device dependent.

11. Making MIDI Audio Creating a MIDI score requires:
Making MIDI Audio
Creating a MIDI score requires:
Knowledge of music and some talent
Ability to play a musical instrument
Sequencer software
Sound synthesizer
Built into PC board
Add-on for MAC
MIDI can synthesize over 100 instruments

12. Making MIDI Audio You will need: Sequencer Software (Smart Score)
Making MIDI Audio
You will need:
Sequencer Software (Smart Score)
A Sound synthesizer ( built into PC sound board, an add on for MAC)
MIDI keyboard or device
Ability to play the piano and music theory background
or a hired “expert”

13.
MIDI
A MIDI file is a list of commands that are recordings of musical actions, that when sent to a MIDI player results in sound
MIDI data is device dependent
MIDI represents musical instruments and is not easily used to playback spoken dialog

14.
MIDI Audio
MIDI is a shorthand representation of music stored in numeric form.
Since they are small, MIDI files embedded in web pages load and play promptly.
Length of a MIDI file can be changed without affecting the frequency of the music or degrading audio quality.
Working with MIDI requires knowledge of music theory.

15.
Digital Audio
Digital audio represents a sound stored in thousands of numbers or samples.
Digital data represents the loudness at discrete slices of time.
It is NOT device dependent and should sound the same each time it is played
It is used for music CD’s

16.
Digital Audio
The three sampling frequencies most often used in multimedia are CD-quality 44.1 kHz, kHz and kHz.
The number of bits used to describe the amplitude of sound wave when sampled, determines the sample size.
Digital audio is device independent.
The value of each sample is rounded off to the nearest integer (quantization).

17. Preparing Digital Audio
Preparing Digital Audio
Balance file size versus quality
Set recording levels
Edit the recording

18. Preparing Digital Audio
Preparing Digital Audio
Balance file size versus quality
To calculate file size in bytes:
Mono: sampling rate  duration of recording in seconds  (bit resolution  8)  1
Stereo: sampling rate  duration of recording in seconds  (bit resolution  8)  2

19.
Digital Audio Editing
Once a recording had been completed, it almost always needs to be edited.
Basic sound editing operations include: trimming, splicing and assembly, volume adjustments and working on multiple tracks.

20.
Digital Audio Editing
Additional available sound editing operations include format conversion, resampling or downsampling, fade-ins and fade-outs, equalization, time stretching, digital signal processing, and reversing sounds.

21.
MIDI vs. Digital Audio
MIDI data and digital audio are like vector and bitmapped graphics:
Digital audio like bitmapped image – samples original to create a copy
MIDI – like vector graphic- stores numeric data to recreate sound

22.
MIDI vs. Digital Audio
MIDI data is device dependent; digital audio is not
MIDI sounds (like vector graphics) are different on different devices;
Digital sounds are identical even on different computers or devices.

23.
MIDI Advantages
MIDI file are much more compact and take up less memory and system resources
MIDI files embedded in web pages load and play much faster than digital
You can change the length of a MIDI file by varying its tempo
With high quality MIDI devices, MIDI files may actually sound better than digital

24.
MIDI Disadvantages
MIDI represents musical instruments not sounds and will be accurate only if your playback device is identical to the production device
MIDI sound is inconsistent
MIDI cannot be easily used to reproduce speech

25. Digital Audio Advantages
Digital Audio Advantages
Digital audio sound is consistent and device independent
A wide selection of software support is available for both MAC and PC
A knowledge of music theory is not required for creating digital audio, but usually is needed for MIDI production
Apple MAC and Window PC

26.
Choose MIDI data
If you don’t have enough RAM memory, or bandwidth for digital audio
If you have a high quality sound source
If you have complete control over the playback hardware
If you don’t need spoken dialog

27.
Choose Digital Audio
If you don’t have control over the playback hardware
If you have the computing resources and bandwidth to handle the larger digital files
If you need spoken dialog

28.
Digital Audio
You can digitize sound from a microphone, synthesizer, tape recording TV broadcast, or CD’s.
Digitized sound is sampled every nth of a second. The more often you take the sample, the better the sound.
Sample sizes are either 8 or 16 bits and common frequencies are , 22.05, and 44.1 kHz

29.
Digital Audio
To prepare digital audio from analog media, record it from a device, like a tape recorder, into your computer using digitizing software.
Balance the sound quality with your available RAM
Set proper recording levels for a good clear recording

30.
File Size vs. Quality
Audio resolution determines the accuracy with which a sound is digitized. (More bits in the sample size produces better quality and larger files)
Stereo recordings are more realistic and require twice as much storage space and playback time.
Mono files tend to sound “flat”

31. Editing Digital Recordings
Editing Digital Recordings
Apple’s QuickTime Player Pro provides for primitive playback and editing
Sonic Foundry’s Sound Forge is a more serious sound editor
These can be used to trim, splice, volume adjustment and format conversion as well as special effects

32.
Audio File Formats
A sound file’s format is a recognized methodology for organizing data bits of digitized sound into a data file.
On the Macintosh, digitized sounds may be stored as data files, resources, or applications such as AIFF (Audio Interchange File Format) or AIFC (Audio Interchange File Conversion).
In Windows, digitized sounds are usually stored as WAV files.
Both can use MIDI files (.mid)

33.
Audio File Formats
CD-ROM/XA (Extended Architecture) format enabled several recording sessions to be placed on a single CD-R (recordable) disc.
Linear Pulse Code Modulation is used for Red Book Audio data files on consumer-grade music CDs.

34. Sound for the World Wide Web
Sound for the World Wide Web
To play MIDI sound on the web
wait for the entire file to download and play it with a helper application
stream the file, storing it in the buffer and playing it while it downloads
Streaming is dependent on the connection speed
FLASH allows sound to be integrated in a multimedia presentation, controlled by buttons and saved as .mp3

35. Adding Sound to a Multimedia Project
Adding Sound to a Multimedia Project
Decide what sounds you will need and include them in the story board or cue sheet.
Decide whether to use MIDI or digital audio
Acquire source material (record/buy)
Edit the sounds
Test the sounds to be sure they are timed properly

36. Adding sound to Multimedia
Adding sound to Multimedia
CD- quality audio
Standard is ISO 10149, a.k.a. the “Red Book Standard”
Sample size is 16-bit
Sample rate is 44.1 kHz
11 seconds of audio uses 1.94 MB of space

37. Professional Sound The Red Book Standard- ISO 10149 www.hndit.com
( 16 bits at 44.1 kHz) allows accurate reproduction of all sounds humans can hear
Software such as Toast and CD-Creator can translate digital files from CD’s directly into a digital sound editing file or decompress.mp3 files into CD-Audio

38.
Professional Sound
Compression techniques reduce space but reliability suffers.
Space can be conserved by downsampling or reducing the number of sample slices taken per second.
File size of digital recording (in bytes) = sampling rate X duration of recording (in secs) X (bit resolution/8) X number of tracks.

39. Advanced Sound Management
Scripting Languages such as Open Script (Toolbook), LINGO(Director), or Action Script ( FLASH) provide better control over audio playback
Requires some programming knowledge

40.
Production Tips
Vaughn’s Law of Minimums - there is an acceptable level of adequacy that will satisfy the audience;
If your handheld microphone is good enough to satisfy you and your audience, conserve your money and energy.

41.
Production Tips
Recording on inexpensive media rather than directly to disk prevents the hard disk from being overloaded with unnecessary data.
The equipment and standards used for the project must be in accordance with the requirements.
Sound and image synchronization must be tested at regular intervals

42.
Production Tips
Audio recording - use CD’s, or VCR tapes, or DAT ( digital audio tape) tapes
Create a good database to organize your sounds, noting the counter and content
Testing and Evaluating- (delaying a fast machine if needed to sync with animation)

43. Production Tips Copyright Issues
Production Tips
Copyright Issues
Securing permission for the use of sounds and music is the same as for images
Can buy royalty-free digitized sound clips
DO NOT use someone’s original work without permission!

44. Summary
Vibrations in air create waves of pressure that are perceived as sound.
Multimedia system sound is digitally recorded audio or MIDI (Musical Instrumental Digital Interface) music.
Digital audio data is the actual representation of a sound, stored in the form of samples.

45.
Summary
MIDI is a shorthand representation of music stored in numeric form.
Digital audio provides consistent playback quality.
MIDI files are much smaller than digitized audio.
MIDI is device dependent digital audio.
MIDI files sound better than digital audio files when played on high-quality MIDI device.