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In the previous article it was noted tha nowadays the software will play a much more crucial role in the development of Hi-Fi Audio appliances.
One understands that the information has to be compressed in order to save that extra bit which will make our transmission less heavy to pocket and patience of our intended audience. The first players took into account the repetition of information, and by avoiding retransmission of useless information managed to achieve a good compression ratio. For example consider a song that has a silence for 10 seconds, and that was sampled at 44.1kHz. Instead of transmitting 0's 440,100 times an encoding/decoding algorithm was written to tell the player "now output a zero and keep it there for 10 seconds". Such an instuction is much more efficient that the deaf-dumb and blind original digital transmission. Yet, the time went by and more economy was required. Even more complex algorithms were employed. But after a certain point, the generic compression algorithms (i.e. algorithms that are use for compression of digital information regardless of its kind be it music, pictures or just characters) were found to be making a great injustice to the particular type of information. Pictures were "broken" or lost their brightness, and sound was sounding nothing like the original, even hurting the ears of the listeners. Here came the Psycho-Acoustics. Psycho acoustics puts the human ear first while attempting to efficiently compress the information. Just consider that the human brain is able to fill the gaps between the frames in the common TV transmission... Although the eye doesnot see a continuous signal, perceives the discrete images in a cartoon that follow one another in a given rate (which varies from person to person)as a continous, smooth movement... Similarly the brain perceives audio signals in a similar manner. There are sounds that annoy it or please it more than others. Modern Signal Analysis tools (such as Fourrier Transform) were able to provide to methods that help us produce a better listening sound, to compensate for the inefficiency and the inaccuracy of the audio machines. If for example you analyse a sound to its harmonics and try to find the impact of reducing the amplitude of each harmonic in an audience, you will find - statistically - that most people are quite happy with having the Third Harmonic completely damped. Without the third harmonic the sound is more pleasing. Go To Page: 1 2
The copyright of the article Psycho-Acoustics... Sensing music.. in Audio Equipment is owned by . Permission to republish Psycho-Acoustics... Sensing music.. in print or online must be granted by the author in writing.
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