Using Sound in Games Alex Baumann

Outline 3D Spatialization Getting and Editing Sounds Using Sounds in Games Music in Games Example Videos

3D Spatialization Sounds are given 3D spatial location relative to user Can be achieved with stereo (headphones work best) or more significantly with 5.1 or above Location of sounds is simulated by altering phase and reverberation on sounds Achieved in these systems using Fourier Transforms

3D Spatialization Sound impulses are created from sources in an anechoic room These are measured at both “ears” on a dummy head Fourier transforms of the resulting sound at ear drums is created These functions map input signal to output signal as a function of position around user

3D Spatialization Fourier functions are used to convolve sound modeled on dummy with the sound to be spatialized Quality determined by measured Fourier functions and FFT convolution Used in OpenAL by specifying locations in space OpenAL also adds the Doppler effect to moving objects

Getting and Editing Sounds Most game sounds would be either sound effects or music (also voice, etc) Both can be had from professional CDs (music or sample) or created For creating sound effects the free approach is to download free samples and edit with a free editor

Getting and Editing Sounds Free Samples: Includes tons of real world samples, all free to use and a great source of sound effects Free Editor: Includes effects to alter the sounds you download and edit them for time, etc

Getting and Editing Sounds Some sound effect tricks: Play with pitch – bringing the pitch down significantly can create complex and dark ambient textures Add reverb makes sound fuller, more ambient Use equalization to remove bass, mid or treble frequencies Layer sounds together

Getting and Editing Sounds With a microphone and a decent sound card you can record and edit your own sounds It can be difficult to get a good recording because of background noise and recording conditions I would suggest to look on freesound.iua.upf.edu first for samples

Getting and Editing Sounds Original Sound (windchime): Edited Sound (layered, same sample):

Using Sound in Games Spatialization allows use of mono (not stereo) samples Multiple versions of the same sample can be used in different 3D locations with different pitch to simulate different objects Both of these techniques would save memory and load time

Using Sound in Games Most sound effects would be triggered by actions, although background textures may be long loops Interacting with an object (i.e. hitting it) can trigger different samples, or you could change pitch and amplitude on the same sample You may have 4 different versions of a sound for how hard an object is hit, and add subtle random variations in pitch and amplitude

Music in Games Most people would probably opt to use music from CDs, but production on a computer has gotten much easier Many packages offer free music samples (with loops you can layer) Just need a somewhat low latency soundcard

Music in Games Sony offers ACID XPress for free, which is mostly loop based Propellerheads’ Reason is one of the most popular all-in-one music production suites (also cross platform) Looks like a customizable rack of real musical gear and is easy to use

Music in Games Reason is quite efficient for synthesis (pretty low CPU) and sounds good Includes synthesizers, samplers, drum machines and effects Limited feature set for professionals, but is excellent for beginners and can be used as a plug-in into larger systems

Music in Games Reason 4 Screenshots:

Videos Not gaming related, but tightly coupled between video/animation and sound…