ITEC 715

1
ITEC 715

• Computer Foundations for Instructional Multimedia

Week 7
2
ITEC 715
Recall from Last Week

• E-learning Design Document (EDD) Critiques
• Scripting from your EDD ? Aiming for an 85 (/-
  about 5) match to between the design specified
  in the EDD and the script built from it

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ITEC 715
Scripting from Your EDD

• In many production environments, IDs write
  structured scripts. Typically, this means
  scripts are written inside multicolumn script
  tables, one table per page-type (possibly with a
  header table preceding each content table)

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ITEC 715
Scripting from Your EDD

• Advantages of structured scripts include
• Structured content has a defined space for every
  piece of content and information that is required
  to build the page, and thus minimizes the chance
  that the ID will forget to put in something whose
  absence would slow down the production pipeline
• Structured content can be processed by computer
  programs to automate some or all of the build
  process

5
ITEC 715
Scripting from Your EDD

• You wont be using a structured script in the
  class, though
• Instead, simply type your final copy directly
  into PowerPoint. Lay out your final graphics or
  place holders for your animations, videos, media
  controls and other buttons. Place the script for
  any audio associated with a page in the
  PowerPoint Notes section
• In other words, your script for this class will
  be a PowerPoint deck

6
Audio Production for Instructional Multimedia
Module 1 Digital Audio Fundamentals
Sound
Sound is a compression wave in the air. You hear
it because your ears convert the changing air
densities into signals that your brain interprets
as sound. If you were to graph the compression
and rarefaction cycles of a sound wave, youd end
up with something that looks like the picture at
the lower right.
1 wavelength
Diagram source Principles of Digital Audio, 2nd
Edition by Ken C. Pohlmann (1989)
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Audio Production for Instructional Multimedia
Module 1 Digital Audio Fundamentals
Visually Representing a Sound Wave
Usually, when drawing a graph of a sound wave,
the vertical direction represents amplitude and
the horizontal direction represents time. All
sound requires time, so that axis is fairly self
explanatory. But amplitude, which is a measure
of the relative compaction or rarefaction of the
air, is less familiar.
Amplitude (usually in dB) ?
Time (usually in seconds) ?
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Audio Production for Instructional Multimedia
Module 1 Digital Audio Fundamentals
Frequency ? Pitch
Human hearing 20 Hz 20,000 Hz
High frequency Low frequency
Amplitude ? Loudness
Human hearing 0 dB 120 dB
Soft Loud
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Audio Production for Instructional Multimedia
Module 1 Digital Audio Fundamentals
Module 1 Review
Sound compression waves in the air Human
Hearing Frequency range 20 Hz 20 KHz
Dynamic range 0 120 dB Frequency ? Pitch
Amplitude ? Loudness/Volume Sample Rate ?
Highest Freqency Bit Depth ? Dynamic
Range Nyquist Theorem ? Must sample at 2x the
sounds highest frequency
10
Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Module 2 Recording with Audacity
11
Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Microphone
Now that you understand the fundamentals of
digital audio, youre ready to start making some
digital recordings of your own. To do so, youll
need two things (at minimum) a microphone and
some digital audio recording software. A limited
number of mics are available for checkout from
SFSUs Cahill Lab, Burk Hall 319. If you want to
buy one, a relatively decent, inexpensive
microphone that will work well for this purpose
is the Radio Shack Hands-Free Tie-Clip
Omni-Directional Electret microphone (part
number 33-3013), pictured at right.
Necessary Equipment A Microphone
12
Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Audacity Software
Youll also need some software to digitize the
signal from our microphone. The software youll
be using is called Audacity. Audacity is free
software, available for all three popular home
computer operating systems Linux/Unix, Windows,
and Mac OS X. Audacity is already installed on
the computers in this classroom. To get Audacity
at home, download it from http//audacity.sourcefo
rge.net/
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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Making a Recording
Your goal is to record sound so that its loudest
portion comes as close as possible to the top and
bottom of your work window (the 1.0 and -1.0
lines), but no farther.
Too Soft
OK
Too Loud
Sound source Its Just A Thing by Kurt Elling
from The Messenger (1997)
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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Clipping
Remember that amplitude values you can measure
are directly related to how many bits youve
devote to each measurement. If your sound level
is so high that you run out of bits trying to
measure it, you get clipping. Waveforms with
clipped peaks sound distorted. Generally, this
is something you want to avoid.
Clipping
Sound source Its Just A Thing by Kurt Elling
from The Messenger (1997)
15
Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Room Tone (cont.)
Rooms of differing sizes and differing
configurations have different-sounding room
tones, but since you cant have sound without air
(remember sound is density changes in air), room
tone will always be present when you make
recordings indoors.
noise floor
True silence
noise
signal
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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Making a Recording
Go to beginning
Play

• Launch Audacity
• Choose File - Preferences
• Click on the Quality tab
• Select your sample rate (you can leave everything
  else at the default values)
• Push the big red Record button
• Set your levels by speaking into the microphone
  and then seeing how hot your signal is
• When youre done recording, press the yellow
  Stop button

Record
Pause
Stop
Go to end
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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Editing a Recording Useful Audacity Tools

• Selection Tool Use this to select subsections of
  your sound. Once selected, these portions of
  your sound can be deleted, or effects can be
  applied.

2a. Magnify Tool Use this to zoom in or (with
the Shift key held down) to zoom out.
2b. Magnify/Unmagnify Tools You can also zoom in
or out using these tools.
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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Saving a Recording

• Save the Audacity Project file first by choosing
  File - Save Project As
• Finally, export the WAV file by choosing File -
  Export as WAV

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Audacity, Part 2
This Week
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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Normalizing and Digital Noise Reduction
Selection Tool

• Select the entire wave (cmd-a)
• Choose Effect - Amplify
• Accept the defaults and hit OK to normalize the
  sound (peak normalization)
• Using the Selection Tool, select a passage that
  is supposed to be silent
• Choose Effect - Noise Removal and press the Get
  Noise Profile button
• Select the entire wave (cmd-a)
• Choose Effect - Noise Removal
• Adjust the slider (usually toward less) and use
  Preview until it sounds good. Then press the
  Noise Removal button.

Noise Removal
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Audio Production for Instructional Multimedia
Module 3 Delivering Audio to Flash and the Web
Some Background Info About the Mp3 Format
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Audio Production for Instructional Multimedia
Module 3 Delivering Audio to Flash and the Web
Lossless vs. Lossy in Audio Encoding
WAV files are generally too big to deliver in an
online instructional multimedia product. Thats
why you will often want to compress your WAV
original into a smaller mp3. How does the mp3
encoding process manage to squash the size of the
sound down so much? The answer is it throws
some of the sound information away!
Relative sizes of a 1 minute sound
The mp3 file is much smaller because it throws
away some audio information.
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Audio Production for Instructional Multimedia
Module 3 Delivering Audio to Flash and the Web
Lossless vs. Lossy in Audio Encoding
There are two kinds of data compression
lossless and lossy. Compression schemes like
Stuffit and Zip are lossless. This means that
when you uncompress a file that has been
Zipped, you get back a file that is identical
to the file you originally compressed. But with
mp3s, this is not true. Some information is lost
during mp3 compression and cannot be recovered
during decompression.
Popular compression algorithms, classified as
lossless or lossy. Lossless algorithms recover an
identical copy of the original file. Lossy
algorithms do not.
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Audio Production for Instructional Multimedia
Module 3 Delivering Audio to Flash and the Web
Lossless vs. Lossy in Audio Encoding
Original 44.1 KHz / 16 bit stereo WAV file
The technical term for algorithms which have both
an encoder and decoder part is codec (a somewhat
bizarre contraction of encode / decode). Since
mp3 is a lossy codec, you do NOT want to convert
your sound into the mp3 format until you are
completely done editing it! If you edit an mp3
and want to save it back out as an mp3, youll
have to run it through the mp3 encoder again, and
every time you do that, you will degrade the
quality of your sound.
48 kbps stereo mp3 file 1st Generation
48 kbps stereo mp3 file 10th Generation
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Audio Production for Instructional Multimedia
Module 3 Delivering Audio to Flash and the Web
Exporting Mp3s Out of Audacity
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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Exporting Mp3s from Audacity

• Choose File - Preferences to pop up the
  preferences dialog, then click on the File
  Formats tab.
• Choose a Bit Rate lower bit rates result in
  smaller files but worse sound quality.
• Hit OK to save your settings.
• Choose File - Export as Mp3
• Give the mp3 file a name. Hit Save, then on the
  following dialog box, just accept the defaults
  and hit OK.

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Creating Royalty-FreeMusic with GarageBand
Background Music
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ITEC 715
GarageBand

• Other sources of royalty-free background music
  include
• Additional GarageBand Jam Packs
  http//www.apple.com/ilife/garageband/jampacks/
• Royalty-free library music (do an Internet search
  on royalty free music)
• Output of other loop editors such as Soundtrack
  (Apple), Sonys Acid (PC), and Adobes Audition
  (PC)

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Audacity, Part 3 Mixing Voice-Over Narration
with Background Music
Mixing Voice and Music
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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Voice-Over Mixing

• Write a script and rehearse it before recording!
• Launch Audacity
• Record and edit your voice track
• Save your work!
• With the completed voice track still loaded,
  choose Project - Import Audio to import your
  music track
• Next, split your stereo music track into two mono
  tracks by using the drop-down menu by the track
  name and choosing Split Stereo Track

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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Voice-Over Mixing (cont.)

• Next convert each of the 2 split music tracks
  into a mono track, again using the drop-down
  menu by the track name.
• Select the two music tracks by clicking on track
  control area (use shift-click to select the
  second track).
• Now mix these two music tracks together into a
  single mono track by choosing Project - Quick
  Mix.

NOTE If we were mixing two tracks that werent
already part of a clean stereo mix, wed want to
make sure there was no clipping in the newly
combined mono track.
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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Voice-Over Mixing (cont.)

• Use the Time Shift Tool to move the tracks
  forward or backward in time.
• You can also use the Selection Tool to highlight
  sections of the music track you dont want such
  as introductory passages from the beginning and
  delete them using Edit - Cut or the equivalent
  keyboard shortcut cmd-x
• While testing out ideas, you can adjust the
  relative levels of each track using the volume
  slider on the tracks left

Time Shift Tool
Track Volume
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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Voice-Over Mixing (cont.)

• With the voice and music track lined up as you
  want them, youre ready to start adjusting the
  relative volumes of the tracks by using the
  Envelope Tool
• Click with the Envelope Tool to create new pivot
  points for the envelope curve. Drag the line to
  adjust volumes up or down as desired.
• Let the music run for 5-10 seconds past the end
  of the narration. Use the selection tool to
  create a fade-out (Effects - Fade Out) over the
  last 5-10 seconds. Fade the same section out
  twice to get a smoother curve.

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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Voice-Over Mixing (cont.)

• Select everything after the fade-out on the music
  track and delete it
• Save the Project file at this stage with a name
  ending in -u, then save it again with the same
  name, but ending in -m instead of -u. That
  way well save our unmixed and mixed
  versions. If we discover problems later, we can
  remix without having to do all Time Shift and
  Envelope work again.

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Audio Production for Instructional Multimedia
Module 2 Recording with Audacity
Voice-Over Mixing (cont.)

• Select both tracks, then choose Project - Quick
  Mix to mix the VO and music tracks into a single
  monophonic track.
• Listen to the track to make sure that combining
  these tracks didnt cause any clipping. If it
  did, undo the Quick Mix, take each track down 3
  dB, and do the Mix again. You should re-normalize
  this final track as well.
• Save the Project file at this stage over the file
  name ending in -m.
• Choose File - Export as WAV to save the WAV file.

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ITEC 715
For Next Week

• Continue scripting your course!
• Find or create some music for your splash page
• Mix that music with a spoken welcome message. In
  this mix, the final file should begin with music
  only, at full volume. The music should then fade
  down to a softer volume when the voice comes in
  and while it is speaking. As the voice finishes,
  the music should swell up to full volume again,
  hold for a few seconds, and then fade out.
• Turn in your audio as both the Audacity Project
  file and as a 44.1 KHz, 16 bit stereo WAV or AIFF
  file
• Download and read the ITEC715-Week08.ppt slides