Digital Sound

Digital Sound

1. A sound card translates between the outside world's analogue information and a computer's digital information. It uses an analogue to digital convertor (ADC) to change sound into a digital format the computer can understand, and a digital to analogue convertor (DAC) to change digital information into sound that you can hear.

   • A microphone is able to convert the vibrations in the air into a voltage that is passed through a cable. The voltage is passed into a Sound Card where it is converted into data that computers can store and process. This data can then be saved as a sound file. (mp3, wav, wma) You need to be able to explain how this process works.

2. How we hear sound

   • Vibrations hit our ear drum, causing it to vibrate. The ear drum is connected to neurons in our brain. The vibration of the ear drums sends an electrical signal through the neurons and our brains interpret this signal as sound.

3. The Sampling Rate is the frequency of the samples taken. How many samples are taken each second? Measured in Hz / kHz Bit Depth is the number of different sound levels that the sample can be recorded at. This is the range of different possible volumes for the sound

4. Sampling Frequency – 44.1 kHz (Over double 22 kHz), 48kHz (Video Sound Files, DVDs), 8kHz (Telephones, VOIP Programs) Will have a big impact on the quality of higher frequency sounds (High notes), but little impact on standard frequency sound such as speech. Bit Depth – 16 bit (CD, DVD), 24 bit (Recording), 32 bit (Audio Editing) Big impact on the Quality of Audio. Very drastic effect if the audio file includes a range of both loud and quiet sounds.

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