Input Devices – Sound
Higher Computing Systems - Peripherals Infosheet 3.7
The simplest form of input device for sound is the microphone. This involves the use of software which samples
the incoming signal. An analogue to digital converter is required to convert the electrical signals from the
microphone into ones which can be stored by the computer. This is usually done by a sound card which allows
the microphone to be attached to the computer and sound to be captured.
Sample Size
The sample size is measured in bits. The two most common sample sizes are 8 bit and 16 bit
samples. This is the size of number stored for each sample. 8 bit numbers take only one byte of
memory and 16 bit numbers take two bytes of memory on your computer. The sample size effects
the ‘granularity’ of the sound. 8 bit numbers can only have a range of 0 to 255 whereas 16 bit
numbers can range from 0 to 65535 and so can represent the sound with greater definition.
If you record a sound at 11KHz 8 bit mono for one second it will take up about 11k of disk space
whereas the one second of sound recorded at 44KHz 16 bit stereo will take up about 172k of disc space.
Accuracy
The sound card being used will be the main constraint on the accuracy of the sound sampling. The number of bits
used to store the data is typically a measure of how accurate a sound card is.
Capacity
A sound input device is unlikely to have much of its own cache. It will generally
depend on fast access hard disk space to store the sample.
Speed
The speed of conversion from analogue data to digital data will be relevant.
Cost
For a sound card the number of bits being used in the conversion process will affect the overall cost. While a
simple 8 bit sound card can be bought very cheaply a 64 bit CD quality stereo card will be far more expensive.
However, other factors will dictate a sound card’s cost. These are:
§ the number of connections available e.g. MIDI, Mic in, CD, digital out etc;
§ capablility of card e.g. wavetable synthesis;
§ on board RAM.
Examples Cost Connections Bit
Genius Sound Maker 4.1 PCI £9.50 Mic in, line in/out, Game/MIDI 32
Creative Sound blaster Live £25.00 CD, AUX, TAD, CD SPDIF, 24
MIDI/Game, mic in, line in/out
Compatibility
Sound cards can be used on most computer systems depending upon the operating system, processing power and
RAM of the computer used.
Example
Creative Sound blaster Live Minimum system requirements:
166MHz Pentium, 32 Mb RAM, PCI slot and CD-ROM drive
Supports Windows 95/98/98SE/2000/ME/XP
(25 pages)
(17 pages)
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Comments to this Manuals