Introduction:
In 1986, designers at Sony began the quest to develop a sound medium that combined the benefits of the compact disc, such as sound quality and track accessibility, with the recordability of the cassette tape, in a player with unprecedented portability. They gave engineers the task of creating what would later be called the Minidisc, a wallet sized unit that could record, play, and store music on cartridge enclosed discs. Engineers integrated several technologies to produce the Minidisc, all utilizing the laws of physics. They found that:
-Laser optics would be the obvious choice for reading data.
-Magneto optic technology would be created to record information.
-To allow recordability, new disc properties had to be defined.
-Compression and acoustic principles would be incorporated to store information on a disc 1/5 the size of the compact disc.
The laser used in the minidisc player serves two purposes. Its primary role is to read digital information in a similar fashion as a CD player. Its secondary, but equally important, function is to supply focused heat to the minidisc itself during the recording process.
LASER HEAT: The minidisc recording system takes advantage of a discovery by Pierre Curie in the 1880's. He found that when iron is heated up to a certain temperature, now called the Curie point, it loses its magnetic properties. Similarly, when the minidisc laser is directed at a tiny point of the disc during recording, it heats that spot up to 180 degrees celsius, and the disc material loses its magnetic properties. A magnetic field can then be "frozen" onto that point once it moves past the laser beam, storing data. For more information on the recording process, visit...
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...o-acoustic principles, which states that the ear is more sensitive to some frequencies of sound than others. Psychoacoustics also explores the relationship between the intensity of sound (its decibel level) and its frequency. As you can see from the equi-loudness curve below, a low frequency, high intensity wave will produce the same loudness as a high frequency, low intensity wave.The masking of sound is another factor considered during the compression process. This occurs when one sound blocks another sound from being heard. For example, on a crisp fall day you would be able to hear leaves rustling in the wind until a marching band stomps by. ATRAC would omit the rustling leaves data that was masked by the band, saving storage space. Once the audible sound data is singled out, it can easily be compressed and stored with an inperceivable change in sound quality.
Schoenherr, Steven. "Recording Technology History." www.web.archive.org. Steven E. Schoenherr, 6 July 2005. Web. 2 May 2014.
...improve the sound quality was parallel compression. Having applied it, the sound became more ‘solid’ and ‘full’ (Kärkkäinen, 2011) (recordingrevolution, 2010).
fed into a DTS decoder, of which several DTS equipped consumer receivers and processors exist, you get a high quality 5.1 music format. Many people don't realize that there is a viable 5.1 music format available today with a catalog of a couple hundred popular CDs available.
A. DVD discs utilize digital technology, which is the same technology used by compact discs.
Sound travels in the shape of a wave. There are two types of sound waves, longitudinal and transverse [9]. Longitudinal waves travel parallel to the source of the wave and transverse waves travel perpendicular to the source of the wave. Sound is produced from vibrations through a medium, and travels in the form of longitudinal waves [10]. Pitch is the general perception of the highness or lowness of a sound which depends on the frequency complexity, and loudness of the sound [11]; on the other hand, in music pitch related to notes that are being played. The vibrations caused from a disturbance such as a vibrating string create areas of compression and rarefaction of the molecules in the medium that the vibrations are traveling through. Sound is only produced when these vibrations are traveling through a medium. An observer is able to hear sounds because these areas of compression and rarefaction are picked up by the observer's ears, and translated to the brain from longitudinal sound waves. Figure 5 [12] (middle-left) shows the areas of compression and rarefaction in the air in a hollow tube caused by the vibrations from a tuning fork. Compressions are areas of with a high density of molecules; whilst, rarefactions are areas with a low density of
I call this machine, the phonograph. The phonograph is constructed using a metal cylinder, tinfoil, and two diaphragm-and-needle units. The two needles are necessary for the machine to work; one needle records sound and the second takes the sound and plays it back. When using the machine,
How a record player works is quite simple. A motor is somehow connected to a solid disc so that the disc is rotated at a constant speed. On top of the rotating disc (platter), The record is placed on top, with a slip mat in between. The slip mat can serve two functions. In the past to hold the record in place so that it would not rotate independently of the platter. Now, however, the slip mat serves a much different function. Instead of holding the record in place, the slip mat is now used to reduce the friction between the spinning platter and the record. This way a DJ can scratch (manually move the record, usually at high speeds) the record while the platter continues to spin underneath. Once the record is rotating, a stylus glides along the grooves and picks up the vibrations, these are then converted into audible sound.
These two reels along with their reel hubs are located beside each other. When an audio cassette is played, the tape rolled around the supply reel hub is transferred to the take up reel hub, which can be seen through the window located right in the middle of both reels. These spools and other related parts are held inside a protective plastic shell. The Cassette shell is a cover that holds the entire mechanism together as well as protect all other components and from the environment. The other major parts include erase head, Pressure Head, Capstan, Playback Head and Tape Guide. Erase head uses an electromagnet that operates at a constant frequency to erase any information recorded in the past on the tape. Erase head is helpful to reuse the tape to record any other sound on it. Pressure head pushes the magnetic tape against the playback head, to play the sound when inserted in the player. This tape is then pulled by a metal rod known as Capstan. The coil that detects the magnetic frequency of a tape when played, and converts the signals into a sound is called playback head. This read tape is then rolled around the take up reel, by the help of tape guide that are two rotating wheels located on the top right and left corner and guides the magnetic tape from one reel to another. These tape guide also help in fast
In 1958 the RCA which is a tape cartridge could hold up to sixty minutes of music. You would put the cartridges in the music players. The RCA could hold way more music than the records and wax cylinders. They stopped selling these in 1964 because of low sales.
With the invention of the Compact Disc (CD) in 1984 the music industry was able to increase their record revenues again surpassing $4 billion. According to the Recording Industry Association of America (RIAA), profits in 1988 increased up to $6.25 billion (Krasilovsky and Shemel, 2007). On one hand CD’s have proved to be very successful invention as it indicated that consumers are willing to pay for increased quality of goods and services. However on the other hand it had introduced issues relating piracy. Illegal reproduction of analog phonograph records was a relative harmless issue at this time, as the quality of sound would reduce by ea...
one will begin to see more and more documents being on CD-ROM and also on the
Before understanding the physics principles, one must understand the physical design that induces them. A magnetic disk is a flat, circular, rigid sheet of aluminum coated with a layer of magnetic material (can be double sided). The material usually is a form of iron oxide with various other elements added. The disk rotates upon a central axis and a movable read/write head writes information along concentric tracks (circular paths traced out by motion of the disk) on it. Multiple disks can be stacked to store more information. Typically (1985) 11 disks with 22 surfaces, of which 20 are used (minus top/bottom), are manipulated to read/write data.
...ats such as paper based and microfilm. Compare to paper based, it does not change the form of paper even how many years pass. With the proper care of the records, record center or an organization can keep the record almost thirty years until the process of destruction. However, it could not happen to an electronic record, because technologies rapidly change. There always have new software or hardware that will be upgrade and become more advance. Actually, even under the best storage conditions, digital media have a very limited shelf life, generally less than thirty years. The efforts to preserve the physical media thus provide only a short term, partial solution to the general problem of preserving digital information. Given such rates of technological change, even the most fragile media may well survive the continued availability of equipment to read those media.
There are several different storage devices that can be used to store your data. These are the magnetic storage, optical storage, and solid state storage. According to Parsons and Oja (2014), “a magnetic storage devices stores the data by magnetizing microscopic particles on a disk or tape surface” (p
Why would you compress audio? Well there is a simple reason to compress digital audio. High quality uncompressed digital audio takes a lot of space (“MP3 Info”). One minute of CD quality uncompressed audio takes around 10 MB of space and would need about 50 minutes to be transferred over a 28.8 modem. So now digital audio tries to compress digital audio so it would take up less space on a person’s computer and have better quality. The larger the compressed file the better the audio quality of the result (“MP3 Info”). ...