70 year evolution of sound recording.

From bottom to top: shellac 78 rpm record, vinyl 33 1/3 rpm LP record, magnetic tape cassette, digital compact disc, MP3 player, & two USB 3.0 flash drives. Besides the dramatic increase in recording time of each device is the reduction in weight. In the same order, the weight of each is: 326g/11.5oz, 118g/4.2oz, 36g/1.3oz, 23g/.8oz, 8g/.3oz.

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