Research
What Information Did I Come Up With?
When trying to figure out what material will block out sound, we need to know what sound actually is. Sound waves are a “wave” of disturbance in the form of vibrations that transmits energy from a source that causes these vibrations, such as a person’s vocal cords or the ringing of a telephone (TechTarget). Frequencies are one way we measure sound waves, sound waves can come in very low frequencies of 20 Hertz (20 Cycles Per Second) to 20,000 Hertz (highest a human can hear). For a rule of thumb, the highest sound a piano can make is 4186 Hertz (Dangerous Decibels).
Now, how exactly can we hear sound? We hear sound from the sound waves that travel through the air going into our ear canal, they then reach the eardrum. The eardrum merely keeps elements such as water from coming in. After it passes through the eardrum, the sound waves travel through the middle ear bones (or ossicles) into the inner ear. In the inner ear (also called the cochlea from its latin root cochlea or greek root kokhlias, both meaning snail) there are thousands of hair cells, which change the vibrations of the sound waves into electrical signals which get sent to the brain through our hearing nerves, (the cochlear, vestibular, and vestibulocochlear nerves). The brain then determines what the sound is. (Dangerous Decibels)
Now comes the speed of sound, the normal speed of sound is 340.29 m/s (which is about 0.21313 miles per second). Then, because of further advancements in technology, we now have audio players! What is an audio player? An audio player is a device used to play a certain series of vibrations, (also known as music) which is then amplified so that we can hear it. An audio player, such as an MP3 player, a digital form of technology, which plays sound stored in numerical form. Before that, there were LP records and cassette tapes, which used analog technology. Analog technology means that the music is physically or magnetically stored. Music might be twice as loud and have been stored on a plastic groove that was twice as deep as its normal size. (Woodford) The sound then gets amplified by speakers that are made up of a cone, an iron coil, a magnet, and housing (the case). When the speaker receives an electrical input from the device, it sends that electrical current through, causing the iron coil to move back and forth, which vibrates the outer cone at the same frequency, thus amplifying the original sound produced. (Computer Hope) Another way of amplifying sound is when the tiny movements inside the microphone of a coil of wire inside a strong magnet are turned into small electrical impulses, which are then further amplified by an electronic system. (Amplification of sound) Sound gets produced by vibrations, and these vibrations travel in waves called traveling longitudinal waves, which are what we usually hear. These sound waves consist of areas of higher and lower pressures called compressions and rarefactions (Hollis).
Another type of audio player is a turntable, which plays a standard vinyl record, a type of gramophone record that was popular in the 1950s to the 1990’s. A turntable uses a sapphire or diamond needle that rides along the grooves in the record, thus creating music (Record Collectors Guild).
Other types of audio players include a phonograph and an MP3 player. An Mp3 player gets its name from the types of files it stores, MP3 files. MP3 files are files specifically for storing music digitally (Woodford). Phonautographs are similar to a turntable in some ways. A phonautograph scratches on a line coated with a certain material called lampblack, it then amplifies the sound through a horn. The turntable is very similar to this and seems to be an updated version of it (Morton).
Now, sound is measured by a specific scale, often called the Decibel meter. The Decibel meter is a scale that shows how much energy is in sound waves of different levels of hertz. Sound waves at 80-200 decibels carry so much energy that it can actually damage your ears (Woodford).
A hertz is another unit of measurement that measures frequencies in cycles per second (Previously called CPS) (Tech target). Another way of measuring this is called SPL (Sound pressure level) and is measured in Decibels (Instructables).
There are four different eras of sound: the Acoustic era, the Electrical era, the Magnetic era, and the Digital era. The Acoustic era includes everything before 1925, the Electrical era includes everything from 1925 to 1945, the Magnetic era occurred between 1945 and 1975, and the Digital era is everything in music from 1975 to present day (Schoenherr).
The man who was the first to actually discover sound waves was Leonardo Da Vinci, and there are two distinct types of airwaves: electromagnetic waves and mechanical waves. Electromagnetic waves are the opposite of mechanical waves. Electromagnetic waves are waves that can travel through space/a vacuum, while mechanical waves require something else to transport energy to. Sound waves are examples of mechanical waves while light waves are examples of electromagnetic waves (the Physics Classroom).