1. Interactive Media Products - The Use of SoundAll You Need To KnowVolume 1, Issue 1Understanding the use of sound in interactive media productsWaveformsSpecial points ofSound isinterest:produced when Theory of Sound somethingvibrates. The Basics of Sound vibrating bodyRecording causes themedium Analogue versus around it to vibrate. Vibrations in air are called traveling longitudi-Digital nal waves, which we can hear. Sound waves consist of areas ofhigh and low pressure called compressions. Shown in the dia- Applicationsgram on the right is a traveling wave. The shaded bar above it Use of Soundrepresents the varying pressure of the wave. Lighter areas arelow pressure and darker areas are high pressure.AmplitudeThe amplitude is a variable characterizing an oscillation. It givesthe deflection of a physical quantity from its neutral position (0-point) up to a positive or negative value.The amplitude is expressed in a physical quantity for example,as voltage, sound pressure, etc.Amplitudes are expressed either as instantaneous values ormostly as peak values.Amplitude is the variation or displacement of a wave from itsmean value. With sound waves, it is the extent to which air parti-cles are displaced, and is experienced as the loudness of asound.FrequencySound is made up of changes in air pressure in the form ofwaves (See waveforms). Frequency is the property of sound thatmost determines pitch. The frequencies that an ear can hear arelimited to a certain range of frequencies.Decibel Levels (dB)Our ears detect changes in volume in a non-linear fashion. Adecibel is a logarithmic scale of loudness. A difference of 1 deci-bel is perceived as a minimum change in volume, 3 dB is a mod-erate change, and 10 decibels is perceived by the listener as adoubling of volume. Decibels are designated by the letters: dBExamples:0 dB is the threshold of hearingWhisper: 15-25 dBBackground noise: about 35 dBNormal home or office background: 40-60 dBNormal speaking voice: 65-70 dBOrchestral climax: 105 dBLive Rock music: 120 dB+Pain Threshold: 130 dBJet aircraft: 140-180 dB

2. Sound Generator PitchPage 2A sound generator is a vibrat-The sensation of a frequencying object which produces a is commonly referred to as theHertzsound via sound waves. Apitch of a sound. A high pitchsound generator is an objectsound corresponds to a high Sound travels through air asthat makes sounds. Thesefrequency sound wave and awaves of increasing and de-sounds may be produced in a low pitch sound corresponds creasing changes in the pres-nearly infinite number of ways, to a low frequency soundsure of the air. The number ofranging from a foot stompingwave. complete sound waves movingon the floor to a fire engine past a point is called the fre-siren. Regardless of the origin Frequency quency, which is measured inof the sound, it is always thehertz (Hz).As a sound wave movessame thing vibrations in thethrough a medium, each parti-air that make a pattern recog-cle of the medium vibrates atnizable by aural senses. Whilethe same frequency. This isthe ways to make sound aresensible since each particlenearly limitless, practically allvibrates due to the motion ofsound-generating objects fallits nearest neighbor. The firstwithin two main categories:particle of the medium beginssingle-tone and multi-tone.vibrating, at say 500 Hz, andEach of these processesbegins to set the second parti-makes a full and completecle into vibrational motion atsound pattern, but in differentthe same frequency of 500ways.Hz.Basics Of Sound RecordingMicrophones ground noise or hiss. On theother hand, a very high levelAny sound from the real world signal can cause distortion,must first be converted into anwhatever the control setting.electrical signal by means of amicrophone. All microphones Most types of analogue audiocontain some form of dia- mixer or mixing desk have aphragm that moves under the microphone input and a lineinfluence of the sound pres-input on each channel. Alt-sure waves. This is either part hough the level of each soundof a capacitor, as in a capaci- source can be adjusted bytor or condenser microphone,means of a channel fader, theor is mechanically linked to adefault gain of a channel iscoil, as in a moving-coil micro-set by additional controls,phone.usually of the rotary type.A capacitor microphone usual- Mono & Stereoly has a built-in amplifier, re-quiring a battery inside theCare must be taken to ensurethat those with mono equip-microphone or an externalsource of power. In a profes- ment can hear everything insional studio, the mixing deskyour recordings. Its very easyto create wonderful stereo,provides phantom poweralong the microphones con- containing out-of-phase com-necting cable.ponents, which cant be heardin mono. A mono output canMixers & Signal Levelsbe obtained from a stereomixing desk by simply combin-Most analogue audio devices ing the left and right handonly accept signals within achannels via a buffer amplifiergiven range. If the appliedand a 6 dB attenuator or pad.signal is too low you must turnup the volume or gain control,possibly introducing back- 3. Volume 1, Issue 1Page 3Analog Vs. Digital Sound RecordingAn analog recording is oneExamples of properties thatrecorded onto a digital storagewhere a property or character-are modified are the magneti-medium such as a compactistic of a physical recording zation of magnetic tape or the disc or hard disk.medium is made to vary in a deviation of the groove of amanner analogous to the vari- gramophone disc from aations in air pressure of the smooth, flat spiral track.original sound. Generally, theair pressure variations are first A digital recording is producedconverted into an electricalby converting the physicalproperties of the originalanalog signal in which eitherthe instantaneous voltage orsound into a sequence ofcurrent is directly proportionalnumbers, which can then bestored and read back for re-to the instantaneous air pres-sure. The variations of the production. Normally, theelectrical signal in turn are sound is transduced to ananalog signal in the same wayconverted to variations in therecording medium by a record- as for analog recording, anding machine such as a tapethen the analog signal is digit-ized, or converted to a digitalrecorder or record cutterthevariable property of the medi-signal, through an analog-to-um is modulated by the signal.digital converter and thenSound In Interactive Media ProductsSound is used in plenty ofplosions, dialogue etc. Thismedia applications such asadds to the excitement andDVD interfaces, video games,realism of the current videomobile phones etc. Concerning games on sale.DVD interfaces, sound is usedin many different ways. For Mobile phones are potentiallyone of the greatest of inven-example, the title screen mayinclude the soundtrack or tions ever created. Now withquotes of the movie to addthe new iPhone 5 released,the realization of endless pos-drama or suspense to theaudience. It also may make asibilities concerning mobilenoise when the cursor havephones seems phenomenal.However, since the first re-moved from one selection toanother. This noise happens inlease of even telephones theyplenty of other applicationshave always made a soundthat indicates someone isand is primarily used to informthe user that they have donetrying to contact them. Nowa-something. Although not a days, ringtones for mobilescan be set to almost anything.sound, DVD interfaces alsousually allow the audience to But also, different sounds orchoose the subtitled option for noises can be used for differ-ent notifications on a phone.the duration of the film. Simi-lar to DVD interfaces, videoFor example there can be dif-games regularly contain sound ferent sounds for phone calls,text messages, Twitter/in main menu scenarios, most-ly for the same reason of FaceBook notifications etc.DVDs. However, for example ashooting game will have plen-ty of sound during gameplay.Such as: gun shots, cries, ex-