03/22/2011

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Your best friend calls you and tells you he/she's really sick? How do you show you care? Sound Design and Production<br/> Audio environment<br/> Sound can be reproduced in different ways to create different audio environments. There are two main methods of reproducing sound, monophonic and stereophonic.<br/> Monophonic means that the sound only has one channel. This means that the sound is recorded using a single microphone or the sound from multiple microphones have been combined to create one output signal. The most common use of monophonic sound today is the recording, reproduction or broadcasting of speech as stereophonic sound is not required and a mono signal is often stronger.<br/> Stereophonic sound is a much more popular way of working with sound because it allows two channels to be used to create the illusion of a 3D audio environment. Left and right speakers are used and when synchronised correctly sound can appear to come from anywhere between them. There are lots of examples of effects created using stereo sound and a set of headphones. Here is a link to you tube video where someone has used the sound editing tools in Little Big Planet to create a level were sounds can seem to be coming from certain objects:<br/> <p class="asset asset-video"> <object width="560" height="340"><param name="movie" value="http://www.youtube.com/v/wJnhyNid4g0?version=3"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/wJnhyNid4g0?version=3" type="application/x-shockwave-flash" width="560" height="340" allowscriptaccess="always" allowfullscreen="true"></embed></object> </p> It doesn’t just stop at two channels. Surround sound systems can contain multiple channels and speakers placed in front, either side and behind placed specifically and phased correctly to create a whole sound field to work with. In the case of the cinema sound can be made to sound like it comes from anywhere in the room, the star wars films were the first to use this effectively making the audience feel like they were in the space battles and the ships were flying above and amongst them. Special speakers called subwoofers are even used to produce sounds on the lower boundaries of human hearing capabilities and create vibrations that you can actually feel.<br/> Audio limitations of game platforms<br/> Game platforms have huge influence in the sound design and production for video games. When games were first starting to be developed the sound was very limited by:<br/> • Memory – Sound files take up a lot of space and the size of sound files increase along with the quality. This is why the sound quality of old games is much more limited than newer ones. Storage devices for video games like cartridges, CD’s, DVD’s and Blue Ray have increased in memory size as the new generations of platforms are created. For example the first 7inch floppy disks used for early PC games like ping pong could only store around 100k. Floppy disks grew in memory and shrank in size like most memory storage devices, reaching 1.4M. SNES cartages didn’t reach more than 1M in size. The original game boy game cartridges only stored 256 KB to 8 MB. The generation of CD reading consoles had up to 700k to play with. PlayStation2 read DVD’s that could hold up to 4.7G on single sided, single layered disks. The Game Cube used a unique storage medium; they used optical disks that stored around 1.5G. Today modern consoles are reading blu ray disks that store up to 25G single layers but with the introduction of downloadable games using things like steam the size of games are only limited by the size of the buyer’s hard drive and the speed or capabilities of their internet connection.<br/> <br/> <br/> 8inch 100k Floppy Disk NES Cartridge 250G Hard Drive<br/> • Sound Cards - The sound cards determined how many different voices or channels can be processed and outputted. The older soundcards used for games also didn’t have enough power to process sound files with high bit depths or sample rates. For example the Magnavox Odyssey was only capable of 1 channel monophonic outputs but now the Xbox360 supports 48 kHz 16-bit audio, 256 channel surround sound output.<br/> • Audio output systems – This is also affected by the sound card. The old game consoles were only capable of outputting mono sound and therefore only used single speakers but advances in sound technology brought stereo and now surround sound systems can be used for our games.<br/> Audio recording systems<br/> There is analogue recording and digital recording. The analogue recording technique used to make records used the displacement of a microphone diagrams sensitive to the changes in atmospheric pressure that sound produces and created a geographic representation of that movement on the record surface. Another analogue recording technique was magnetic tape which created readable magnetic footprints representing the electrical signals created by the sounds on the surface of the magnetic sensitive tape. Digital recording means that the sound will be converted from an analogue sound wave to a numeric value, in the case of our computers a binary value. There are two main things that affect the quality of digitally recorded sounds, the sample rate and the bit depth. These are very similar to the frames per second that movies are recorded and the bit depth of a photo.<br/> - Sample rate<br/> The sample rate is similar to the frames per second of a video. Instead of referring to the amount of images that are taken per second the sample fate refers to the amount of “snapshots” of audio are taken per second. In the same way that the more pictures per second a movie is recorded the more accurate and more flowing it will look, the more samples of audio taken per second will make the sound more accurate and flowing. The sample rate directly affects the size of the sound data. Low sample rates are used in things like telephones were high quality is not needed and the amount of digital information needs to be kept to a minimum to allow for easier transportation. Sample rates below 44.1k start to noticeably deteriorate in quality to human ears because of the “nyquist frequency” formula that indicates that the sample rate must be double the desired range. Human hearing range is approximately 20khz.<br/> - Bit depth<br/> Bit depth is similar to the resolution of a photograph. It refers to the amount of bits you have to capture an audio. The amount of bits effect dynamic range, the more bits, the more possible levels, the more accurate the recording will be. The bit is the basis of how a computer works; it is either a 1 or a 0. If you have a bit depth of 8 it means you have 8 slots that can be either 1 or 0 allowing 256 different combinations (levels) to work with. Every time you add a bit depth it doubles the amount of levels. This also means that the Bit depth, along with the sample rate, directly affects the size of the file so you must balance quality with space.<br/> Most sound recording, particularly in the case of music is now done digitally and it’s not just a case of playing into a single microphone anymore. To achieve stereo or surround sound capabilities sound is recorded using multiple microphones strategically positioned around the source. Whole studios have been built to accommodate different recording atmospheres to get a desired effect.<br/> Sound file formats<br/> There are hundreds of different sound file formats, most are specific to audio editing software but here are some of the common ones along with there advantages and/or disadvantages:<br/> • .mp3 – mp3 was developed by the Moving Pictures Experts Group. These files were made to encourage music downloads, they are compressed to a tenth the size of .WAV or .AIF files but still maintain the quality of a CD. The type of compression they use however is lossy. This means that every time it is compresses or saved then it losses a bit of its quality. They are widely supported by most music players and software.<br/> • .wav – Wav stands for “Waveform Audio File Format” it was developed by Microsoft and therefore is most commonly found on windows based computers rather than Mac’s. This file format uses no compression and allows the saving of different sample and bit rates.<br/> • .aif – AIF stands for “audio interchange file format” this is apples response to the .wav file format. It does everything a .wav file format can do and is basically used to store CD audio. They use a sampling rate of 44.1khs and 16 bit depth like a CD.<br/> • .flac – flac stands for “Free Lossless Audio Codec File”. This file format uses lossless compression meaning that you won’t loose any sound quality if you save in as this file but it will still be compressed. Flac is also just as widely supported as mp3 when it comes to music players and software compatibility.<br/> <br/>