Allcomputers include a sound card, it may be integrated on the motherboard or asound card in an expansion slot, before their creation PCs could only make abeep sound. The minimum that a sound card will have is four components whichare the analogue-to-digital converters (ADC), digital-to-analogue converters(DAC), ISA or PCI interface to connect the sound to the motherboard, and inputand output connections for speakers and microphone. While some sound cards usea coder/decoder chip known as CODEC that performs as an ADC and DAC in one. When a user speaks or plays sound into a microphone, an ADCworks by translating the analogue waves into digital data by takingmeasurements of the sounds waves at recurrent intervals.
The speed andfrequency of these measurements are called the sampling rate which is measuredin kHz and the more kHz, the more accurate reconstructed sounds will be. TheDAC works the opposite way by reconstructing the original sound, with a highsampling rate the playback can be almost identical to the original. Totransport sound waves through wires causes distortion, which reduces the soundquality – this reduction is measured by two factors, the total harmonicdistortion (THD) as a percentage, and signal-to-noise ratio (SNR) measured indecibels – the measurement of the magnitude of a sound on a scale.
The smallerthe values of THD and SNR, the better the sound quality. More advanced sound cards have more features and a fewsimilarities to GPUs as it is PCB expansion card that can also have its ownspecialised microprocessor – digital signal processor (DSP), which performscalculations for ADC instead of using the CPU to process the data. They mayalso have their own memory to process data faster, the same way a Graphics carddoes. Sound cards may also have additional connections that are housed within abreakout box, including: speaker connections for 3D/surround sound,Sony/Philips digital interface (S/PDIF) which is an FTP (file transferprotocol) used to transfer audio data through an optical or coaxial connectionfor input and output, musical instrument digital interface which is used toconnect synthesizers or electronic instruments to computers, and finally –FireWire or USB which connects digital audio or video recorders to a soundcard. Video games (and movies) use surround sound and 3D sound toreflect the dynamic sound of where the player is located in a game withdirectional sounds that create an immersive, realistic audio experience withthe use of surround sound headsets or home theatre systems.
Some computer’smotherboards, especially in laptops, have an integrated a DPS which may support3D sound or users can purchase external sound controllers which improve thesound quality. There is usually an option within games, movie players, musicplayers, etcetera, that provides the option of mono or stereo. In mono(monaural) sound, only one channel is used, this means the sound that comes outfrom more than one speaker is all the same.
Meanwhile, stereo uses two or morechannels so that the sound coming out of varying speakers is not the same, thiscreates surround sound and makes sound directional.