Updated: Feb 9, 2022
The Voyager Golden Records, launched into space in 1977 by two Voyager probes, contains 155 images of Earth's civilizations, natural landscapes, and the sounds of 55 human languages and creatures. But since it is a 'record', we can use our knowledge of sound to analyze and interpret it a little.
What is most interesting about this gold record is not just what it covers and how it sounds, but the instructions on the back of it. Excluding the sections explaining the position of the Earth's galaxy and the atoms used to define the speed of light on Earth, the rest of the record is devoted to explaining how to understand the use of the record.
The top left of the gold record shows the speed at which the record is to be played. If you have seen a vinyl player, you will notice that the speed is usually selectable and it is stated on the record what speed the record should be played at in order to get a normal sound. The speed of rotation is indicated on this gold record by a series of decimal conversions and multiplying by the speed of light to give a value of approximately 3.6 seconds, which means that it takes 3.6 seconds for the needle to make one revolution on the gold record. The diagram below, using the same solution, shows the duration of the record, 54 minutes 22 seconds. This gives us the correct speed of play for the record.
The content of the gold record contains information on the earth's ecological sounds and languages, which can be heard in the way described above, but the most complicated part is probably how the photographs are stored on the record. This is the process of digitizing and re-encoding the images. The images and music that we play on our computers today are also analogous to signals that are digitized and then decoded into images and sounds, which are just a series of zeros and ones before they are decoded.
Back then, scientists first pixelated all images, each pixel being 4 bits, and 4 bits could display 16 binary results, each binary straight representing a greyscale of color. The top right waveform also has vertical and horizontal lines representing the 1 and 0 values. The lower part of the display shows the length of time it takes to sample the waveform, which is also converted to a sample interval of about 8 milliseconds. The graphs below the waveform display are used to verify that the decoding process is correct.
The main reason for this seemingly complicated decoding process is that there is no corresponding decoding program, as opposed to playing a CD or DVD, where the decoding program is already built into the player so that the information can be decoded and reproduced so easily. This kind of use of sound-carrying information is not uncommon in music equipment, and in the early days of digital discs there was a track that was used to drive the timecode sound information, which at first glance sounded like electronic noise, but this was because the machine had its own decoding process to decode the sound information, not for human ears. This is because the machine has its own decoding process for decoding sound information, not for human hearing. Tech Electronic's digital effects have also used this technology, allowing users to carry digital information through the sound by playing the information file on their mobile phone and then using the pickups on the instrument to transfer the information to the effects to change the parameters directly.
For those interested in the decoding of sound information, there is a detailed decoding guide by the Verge Science team from abroad. You can also listen to this classic gold record on Soundcloud.