Analogue & Digital

Analogue Sound Storage Devices

Disadvantages & Advantages Uses less bandwidth than digital sounds More accurate representation of a sound It is the natural form of a sound Because of editing limitations there is little someone can do to tinker with the sound, so what you are hearing is the original sound You get a perfect copy of the sound Susceptible to white noise Random white noise can cause distortion and signal loss When an analogue sound has been distorted by white noise it is impossible to recover There are limitations in editing Recording analogue sound on tape is expensive if the tape becomes ruined Tape is becoming hard to find It is harder to synchronise analogue sound Quality is easily lost A tape must be wound and rewound in order to listen to specific part of a sound Analogue is susceptible to clipping, where the highest and lowest notes of a sound or cut out during recording

Analogue Signal An analogue signal is a signal of continuously varying quantities. A typical representation of an analogue signal would be in the form of a sound travelling in a wave-like formation. On the terms of recording and storing an analogue sound, the signal being transmitted is modulated, such as either the strength or the sound’s frequency is amplified so that it can be added or subtracted from data. An example of this would be a telephone. As the telephone receives the analogue sound waves produced by the person speaking, those sound waves are turned into electrical vibrations that represent the original sound, before they are transmitted over the telephone line. Radio transmissions work in the same way. Computers than are used to record digital sound, use modems if the sound needs to be turned back into an analogue sound. This is mainly used to transmitted digital sounds of communication lines. However, it is easier for a computer to process digital sounds, so when the computer receives the analogue signals it is then turned back into a digital sound at the receiving end. When recording an analogue signal the sound can be recorded as a physical texture on a record, or it can be recorded as a fluctuation when it is captured on a magnetic recorder.

Analogue Distortion Analogue distortion occurs when a system cannot handle a signal pattern. In order to make the file compatible the system alters the shape of the signal. A common type of distortion is known as clipping. Clipping is when the system cannot cope with the largest levels of the signal and “clips” them off.

Digital Sound Storage Devices

Disadvantages & Advantages Cheaper recording equipment Isn’t easily distorted by white noise Any part of the sound can be viewed or accessed without accessing the entire song Easy to edit A lot of editing tools are available The sound can be edited without destroying the original copy Copies can be made Easy to transmit the data over networks It is easy to use digital signals in multimedia applications Computers are not the most reliable of resources to use, they can crash and cause the data to become corrupt or lost Data can become corrupted When the hard drive used to store the sound becomes full, the hard drive needs to be defragged There is such a vast array of recording devices and formats that it can become confusing to store a digital signal Sound quality is easily lost It is a representation of an original sound Digital sounds can cut out part of an analogue sound wave, meaning that you cannot get a perfect reproduction of a sound Poor multi-user interfaces

Digital Signal A digital sound is a method of reproducing an analogue sound. It is also a form of recording a sound via transforming pulsing sound waves into a digital signal consisting of data. The usefulness of digital audio is its ability to be stored, retrieved and transmitted without a loss of quality. The sound first begins as an analogue sound being produced raw by a source, i.e. a person speaking or an instrument playing. The sound waves are detected by the sensitivity of a microphone. This microphone then records the sound by converting it into electric vibrations which is then read as an electrical signal. The electric pulsations are processed by a computers sound card, which converts this signal into a string of data. In terms of storing a digital signal, the sound is stored on the computer’s hard drive. Incidentally, the data is then safe to access and can be digitally transferred onto a portable device, such as an MP3 Player. One the other hand if the signal needs to converted back into an analogue song, it first needs to be processed by the computers DAC sound card, which reads back the electric signal, which then plays the sound through the computers speakers. The sound returns as an analogue sound.

Digital Distortion Digital distortion occurs when there is too much input signal being sent into an audio track. This is best represented when the sound track reaches such a frequency when it begins to crackle or clicks. Digital distortion is most frequent in high frequency sounds rather than deep pitched ones, however that doesn’t mean that low pitched sounds aren’t susceptible to distortion. Since digital signals are represented in computer binary language, when there is a distortion in the signal, it simply means that there is no single being applied. In other words, the computer doesn’t have enough binary language to represent a signal that has gone over the maximum limitation.

ADC ADC is an abbreviation for analogue-to-digital converter. It is a device used to convert a signal of continuous varying quantity to a digital representation in the form of data. The opposite to this device is known as an DAC, which converts digital sound back into analogue. An ADC is an electronic device that converts analogue voltage to a string of digital data. The digital output uses a coding scheme to represent the varying quantities of the sound wave recorded, for instance a sound wave highest peak could be represented by the highest number on a digital scale, which varies depending on how accurate the digital signal is trying to be. The accuracy of the digital signal depends on the sample rate. The greater the sample rate, the more accurate the digital sound will represent the analogue sound waves recorded. A digital representation of the sound does not capture the entire sound wave produced, for instance some low sampling rates my just capture the peaks and troughs of a sound wave, meaning that any noise recorded between these two points is lost. Dithering can help to improve the quality of sound produced by an ADC converter. Dithering means that a small fragment of random sound is added to the input before it is converted.

DAC DAC is an abbreviation of digital-to-analogue converter, and it is a device that converters the binary of a digital code into an analogue signal. The reverse of this is an ADC. A DAC converts binary numbers into impulses, turning a fixed stream of data into a signal of continuous variants. Most modern audio signals are stored as digital data within a portable device, such as an iPod, however in order for someone to physically listen to that sound it needs to be converted back into an analogue signal. This is where the DAC is utilised. DACs can be found in portable music players, CD players and PC sound cards. Similar DACs can be found in digital speakers, such as USB speakers and in sound cards.