Sound technology

Basics of Sound

• Sound is perhaps the most sensuous element of multimedia

• Types of sound in multimedia– speech– music– special effects– mood-setting background sounds– etc

The power of sound

Although sound is rarely the main content in a multimedia production, remember that

• Sound can make the difference between an ordinary multimedia presentation and a professionally spectacular one

• Misuse of sound can wreck your project

Sound in Multimedia

• To use sound in multimedia you will not need special knowledge about harmonics, intervals, sine waves or notation

• However, you should know the following:– How to make sounds– How to record and edit sounds on your computer– How to incorporate sounds into your multimedia

work

Digital audio

• Digital audio means digitized sound• The source can be whatever, natural or

prerecorded• Digitized sound is sampled sound: every nth

fraction of a second, a sample of sound is stored as digital information (bits and bytes)

Digital audio

• Sampling rate: how often a sample is taken• Sample size: the amount of information that is

stored about each sample• Typical sampling frequencies are 44,1 kHz,

22,05 kHz and 11,025 kHz• Sample sizes are either 8 bits or 16 bits

Editing digital recordings• Trimming: removing dead air and blank space• Splicing and assembly: remove the extraneous noises

and assemble longer recordings from many shorter ones

• Volume adustments: provide a consistent volume level

• Format conversion: convert your file to a proper format

• Resampling or downsampling: if using lower rates and resolutions, but 16-bit sampling rate (to save disk space)

Editing digital recordings

• Fade-ins and fade-outs: to gradually fade-in or –out if needed

• Equalization: modify recording’s frequency content to sound brighter or darker

• Time stretching: alter the length without changing the pitch

• Digital Signal Processing (DSP) (reverberation, multitab delay, chorus etc)

• Reversing sounds

Audio file formats

• There are dozens of them, created for different purposes over the years

• Nowadays the most used digital audio formats are mp3 (computers, portable mp3 players, some DVD players), wma (Windows-only audio format) and rm/ram (RealAudio format).

• Other formats: .aiff, .mod, .snd, .mid, .wav

Adding sound to your multimedia project

• Decide what kind of sound is needed and where you’ll use them

• Acquire source material• Edit the sounds to fit your project• Test the sounds to be sure they are timed

properly

Stereo recording

Dynamic microphone

Capacitor microphone

High sound pressure possible

General microphone

Sensitive, low sounds

Phantom power

Attenuates handling sounds Sensitive to handling sounds

Interview, song, speech, percussions, music

Effects, speech, music

Sphere Heart, cardioid Shotgun Eight