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IMD20503 Digital Audio and Video
Bas ic o f SoundHow sound works
Analog and digital sound technologySound design
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How sound w ork sI m p o rt a n c e o f s o u nd
Sound is essential in communicating knowledge. Sound greatly enhances images and, especially, video or
animation. Sound can manipulate the mood of spectators with
background music and sound effects. Sound can provide continuity to jumpy frame cuts, but
audiences react gingerly to out-of synch dialog and
misplaced sound effects. Enhanced MM in the form of voice-overs, narrations andinstructions.
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How sound w ork sWhat i s sound?
Sound is basically a vibration. (analog) Sound is a force:emotional, perceptual, physical. It can excite feeling and convey meaning Sound is omnidirectional everywhere.
When something makes a sound, it vibrates and emitspressure waves that are received in the human ear. Thebrain interprets these as sound.
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How sound w ork sWhat i s sound?
Simple waveform can be explained as follows; Imagine a rectangular glass tank full of water.
Looking down from above imagine a vibrating object (anelectric toothbrush) being lowered at the side of the tank.
Ripples will spread out let say from left to right. Picture yourself looking through the side of the tank, with
your eyes at water level as the ripples pass before you. What you see is the repeating pattern of the waves created
by the object vibrating in the water. If we speed up the vibration, it will increase the frequency.
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How sound w ork sWaveform / Sound w ave
A waveform or sound wave gives us a measurement of thespeed of the air particles and the distance, which theytravel for a given sound.
Period is the distance between two crests, and measuredin seconds.
A number of crests (peaks) may occur within a second, sothe number of peaks that occur in one second is called thefrequency.
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How sound w ork sNoise
Unwanted sound in a recording. Always avoid noise because it makes it harder to hear the
message that you want to deliver. Examples:
Vehicles (planes, trains and automobiles) Nature (wind, rain, dogs, birds and cats) Machines (computer fans, phones) Electrical (fluorescent light, refrigerator, electrical
circuits) Recording errors (cheap microphones, unbalanced
audio signals, analog to digital conversion inside thecomputer)
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How sound w ork sCo m p o ne n t s o f w a v ef o rm
Acronym : WAVE PFH Wavelength Amplitude Velocity
Envelope Phasing Frequency Harmonics
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How sound w ork sWaveleng th
Literally, the length of the wave. The physical distance through a medium such as atmosphere,
that a soundwave travels to complete cycle.
The length of a wave is measured from one point on thewaveform to the exact point of the next repeating cycle.
It is usually applied to continuous, predictable waves whose
cycles are uniform and easily measurable.Wavelength (distance)
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How sound w ork sA m p l i t u d e
The amplitude measures the relative loudness of thesound, which is the distance between a valley and a crest.
The amplitude determines the sounds volume. Volume is measured by the amount of energy it takes to
create the sound.
The volume of sound or amplitude is measured in decibels(dB). A decibel is the smallest change in loudness that a human
ear can detect. Human hearing ranges from 1 decibel, called the threshold
of hearing, to over 120 decibels, the threshold of pain.
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How sound w ork sA m p l i t u d e
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How sound w ork sVe l o c i t y
Speed through the atmosphere. The speed or velocity in air and other gases depends on
temperature. Speed of sound increase in warm, moist air and decrease
in cold, dry air. Sounds at high amplitude might go father but travel slower
which is the opposite for lower amplitude.
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How sound w ork sEnvelope
Refers to an imaginary curve that wraps the entire waveform,generated by musical instruments
All sound posses a characteristic change in amplitude or loudness as time increases.
The features included in an envelope are attack, decay, sustain and release(ADSR).i. Attack
The sudden increase of amplitude to full sound intensity.ii. Decay occurs just after the attack, is a slight decrease in amplitude.
iii. Sustain
the main part of a note, when it plays for its longest duration or the sound is held.iv. Release
which the amplitude fades out (when lifting a finger from a key).
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How sound w ork sEnvelope
Attack Sustain Release
Amplit
ude
Decay
Duration
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How sound w ork sPhasing
Think of phase as the information our ears use to tell fromwhere a sound originated, because sound arrives at ourears at slightly different times.
measured in degrees (0-360) Types of phase :
In phase Out of phase
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How sound w ork sPhase
When two waveforms matcheach other and are playingsimultaneously they are in
phase. Sound waves which areexactly in phase add togetherto produce a stronger wave.
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How sound w ork sPhase
If one of the twowaveforms is playingback at slightly
different speed, theyare out of phase. It willcaused them to weakeneach other.If one waveform is
exactly 180 degrees outof phase, the waveformwill cancel each otherout and produce silence.
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How sound w ork sPhase
Sound waves whichhave varying phase
relationships produce
differing soundeffects.
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How sound w ork sFrequenc y and Pi t c h
Frequency is the number of cycles that a vibration completes inone second.
Pitch is measured by frequency.
Pitch is the relative tonal highness or lowness of a sound. As an object oscillates more rapidly, it creates a high pitch
sound, which is registered as a high frequency sound.
A low-frequency sound is produced by a slowly vibrating object,such as the thicker strings on a guitar. Frequency is measured in Hertz . The human ear can perceive a range of frequencies from 20 Hz
(Hertz) to 20,000 Hz (Also expressed as 20 KHz).
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How sound w ork sFrequenc y and Pi t c h
Comparison of frequency range
Name Low frequency High frequency Human 20 Hz 20,000 Hz
Cat 45 Hz 85,000 Hz
Dog 50 Hz 45, 000 Hz
Elephant 5 Hz 10,000 Hz
Bat 10,000 Hz 120,000 HzDolphin 1,000 Hz 120,000 Hz
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How sound w ork sOthers
Few objects produce sounds at a single frequency. Mostmusical instruments generate multiple frequencies for every
note, so that the difference between two same-pitchinstruments can be noted, e.g. a violin and a flute or a pianoand a bass.
The combinations of frequencies in an instrument is known asthe timbre .A sound wave has a main frequency and minor frequencies,
referred as overtones or harmonics .Duration measures frequency, amplitude and timbre over time.Fourier Theorem A sound wave is a combination of sinus
waves created during vibration.
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How sound w ork sCo m p l ex s o un d w a v e
A complex sound wave showing a mainfrequency and minor overtones.
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How sound w ork sO c t a v e
a musical term for doubling of frequency. in other words, the interval between a note that plays at a
given frequency and another note that plays at double this frequency.
measurement unit for pitch
Example a pitch at 20Hz is one octave from a pitch at 40Hz.
An Octave shown as two soundwaves with the same amplitude,but with different pitches. Theblack wave has a frequency doublethe red one.
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How sound w ork sShape
Indicates its tonal quality. 3 different shapes:
i) Sine Wave indicates a gentle and smooth, sweet sound
ii) Square Wave reflects a rich and full, harsh sound
iii) Sawtooth Wave indicates a piercing and colourful sound
Generally, the smoother the sound wave, the cleaner and
sweeter it sounds.
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Analo g and Dig i t a l SoundH i s t o r y
Evolution from analog to digital technology. The analog century begins with a nursery rhyme.
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Analo g and Dig i t a l SoundAnalog sound
Analog means the same as or similar to. Root words analogous and analogy, both of which
mean a similar copy. Analog signals are exact replicas of the original sound
source.
Noise exist in the recording ( not the sound source but partof the analog recording). Analog media :
Audio cassette LP record Reel-to-reel tape Broadcast television
l d l d
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Analo g and Dig i t a l SoundAnalog sound ana log m e dia
Audio Cassette
LP record / Vinyl
Reel-to-reel tape
l d l d
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Analo g and Dig i t a l SoundHow ana log rec o rd ing w ork s?
A process of transduction. Transducers are the keys to sound recording and listening. A microphone, a loudspeaker and our ears are all types of
transducer. A transducer is a device that helps to change one type of
energy into another. In terms of audio, it is a device that converts sound waves
into electrical signals and vice versa.
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Analo g and Dig i t a l SoundHow ana log rec o rd ing w ork s?
A l d Di i l S d
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Analo g and Dig i t a l SoundDigi t a l sound
Digital means numbered. Using number is often a more precise way of expressing
information. The conversion of analog signals into a form that a
computer can breakdown. Digital media :
Compact Disc
DAT MiniDisc
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Analo g and Dig i t a l SoundDi g it a l so u nd d i gi t a l m e d i a
Compact Disc
Digital Audio Tape (DAT)
MiniDisc
A l d Di i l S d
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Analo g and Dig i t a l SoundH ow d ig i t a l r ec o rd in g w o rk s ?
Audio becomes digital audio when it passes from ananalog source, such as microphone or audio out of a
keyboard to you PC.
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Analo g and Dig i t a l SoundH ow d ig i t a l r ec o rd in g w o rk s ?
The recording process of a digital system takes samples ofthe analog signals as it enters the system.
In order to get good digital recording, it has to haveenough : Samples per second Bit depth to accurately reproduce the source material
Audio CD uses 44,100hz, stereo and 16 bit samples per
second.
A l d Di i t l S d
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Analo g and Dig i t a l SoundAnalog vs dig i t a l
Which is better? There are differences between analog and digital but
neither is better or worse than the other. They are simply different. But now our focus is on digital audio because :
We will use digital audio most of the time throughsoftware and hardware to create, record and processthe sound work.
The start up expenses are relatively low compared withpurchasing analog gear.
Analog systems (recording and editing) are becomingobsolete.
A l d Di i t l S d
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Analo g and Dig i t a l SoundAnalog vs dig i t a l
Today, every sound designer works in the digital arena. Many professional music recordings in the studio are
recorded on tape. Usually this recording is digitized, processes and edited in
a Digital Audio Workstation (DAW) and then sent back totape or storage medium like a hard drive.
Both the analog and digital processes are at work but thisis changing.
S d D ig
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Sou nd Des ig nWhat i s sound des ign?
What is sound design? How important it is to a visual and nonvisual experience?
Where does it all begins? Sound design is a technical/conceptually creative field. Sound Design can also be defined as: "The manipulation
of audio elements to achieve a desired effect." It covers all non-compositional elements of a film, a play, a
music performance or recording, computer game softwareor any other multimedia project.
A person who practices the art of sound design is knownas a Sound Designer .
S d D ig
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Sou nd Des ig nWhat i s sound des ign?
Area that uses sound designer :1. Theatre
Use large mechanical devices to produce sound
effects. Now, there are 2 roles of sound design in theatre :
Technical Sound Design
Design sound system Conceptual Sound Design
Design what sound to be used to create mood
and setting of the play.2. Radio Use large mechanical devices then better technology
allows sound effects to be recorded and library ofsound was created.
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Sou nd Des ig nWhat i s sound des ign?
3. Film Originally the sound effects was recorded live as
the film was being projected onto a large screen ina recording studio.
Now, sound effects track is complied of manytracks layered together and mixed to form a
dynamic soundtrack. Foley sound effects create sound effects in the
studio by Foley artists.
4. Music Involved in the creation of the overall sound of a
recording and sometimes live performance.
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Sou nd Des ig nWhat i s sound des ign?
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Sou nd Des ig nSound e ffec t s des ign in St a r Wars
Name Effects
R2D2 Half of the sound are electronic and the other half arevocalization, water pipes and whistles
Imperial walkers A machinists punch press along with the sounds of bicyclechains dropping on cement.
Light saber An old tv set along with the hum of a 35mm projecter mixedtogether.
Laser blasts A hammer hitting the wires of a radio tower.
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Sou nd Des ig nSound e ffec t s des ign in St a r Wars
Name EffectsTiefighter An elephants bellow altered in various way.
Speeder bike A P-5 Mustang airplane and a P-38 Lockheed Interceptorcombined and mixed.
Luke Skywalkerslandspeeder
The sound of Los Angeles Harbor Freeway through a vacuumcleaner pipe.
Chewbacca The sounds of walruses and other animals combined together.
Ewokeselanguage
The combination and layering Tibetan, Mongolian and Nepalilanguages.
Sou nd Des ig n
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Sou nd Des ig nSt ages in sound des ign
1. Pre production Story, design document, proposal Spot for sound effects Defining sound effects and sources Sound blueprint and approval process Technical playback considerations
2. Production Sound asset collection
Inventing original sound3. Post production Sound processing
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Sou nd Des ig nPre p roduc t ion
Story, design document, proposal The sound design process starts with a working
concepts. Can be anything from a design document to the mood
of the director or producer has in mind.
Need to get a feel for what the message is going to bein the project. If it is a script, the text need to be reviewed for the
sound conceptualization.
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Sou nd Des ig nPre p roduc t ion
Spot for sound effects Spotting for sound is simply gaining some ownership
to the design document or screenplay. It is a process of literally writing down aural ideas as the
reading occurs.
The processes include: the first impression of the target sketch out rough sound map with the outcome
expected from the project. Write down as many ideas as can fit on the page
because it will save many hours of planning.
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Sou nd Des ig nPre p roduc t ion
Defining sound effects and sources Details on what the sound are and where they are to be
found such as at sound libraries and live recording. Sound designer need to be familiar with sound libraries
and recording techniques.
There are also many online sites that have freedownloadable sounds and fee-based sound for usageand collection not of high quality sound.
A good tips is to start collecting sound your own soundlibrary even if you do not need them in projects becausewe can use them in future works.
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Sou nd Des ig nPre p roduc t ion
www.soundrangers.com
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Sou nd Des ig nPre p roduc t ion
www.partnersinrhyme.com
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Sou nd Des ig nPre p roduc t ion
Sound blueprint and approval process Need to get approval for the work. Categorize the sound based on frequency ranges,
types of sound used and any other characteristic thatcan be defined.
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Sou nd Des ig nPre p roduc t ion
Technical playback considerations When creating the initial plan for the sound design,
consider : What the playback device will be? What platforms?
If it is for the Internet, the bandwidth and the averageplayback system need to be decided.
Compression formats
In film, need to consider theater or cinema standardsie Dolby, THX, DTS
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Sou nd Des ig nProduc t ion
Sound asset collection Start collecting the sound asset based on the pre-
production stage. The sounds can be from sound libraries or source
recordings.
Sound object falls into two types: Single sound Mixed sounds
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Sou nd Des ig nProduc t ion
Inventing original sound Originally recorded sounds are better, more fitting for the
scenario and more original.
2 types of sound effects: Small subject sounds
Glasses clinking, paper being crumpled, door
squeaks, footsteps, cloth movement and humannoises (sneezing, coughing). Recorded in a studio or by Foley artists.
Big subject sounds Sounds that need to be recorded outside such as
explosion, gunfire, crowds, cars, planes, trains andmachinery.
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Sou nd Des ig nPos t Produc t ion
Sound processing Altering and enhancing sounds to fit the scenario. The final stage is mixing and mastering the sound objects. In film, the re-recording process integrates all of the
elements together and mixes them into a compositesoundtrack.
Soundtrack consists of the dialogue track, music track andsound effects track.
The three entities need to be properly mixed and placed inorder to be effective.
The soundtrack should support the visual content andstoryline.
S
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Summary
How sound works Definition
Terms : WAVE PFH Analog and digital sound technology
Analog vs digital Sound design Definition
Stages in sound design; pre production, production andpost production.
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