How can an audio case issue such a powerful sound? Everything happens thanks to the speakera device located inside, capable of converting an electrical audio signal into sound waves. It is connected to a cone and consists of a metal coil and a magnet.
Do you know when the case makes “Tunz Tunz” vibrate with so much intensity? The heart of the system consists of a motor which induces the oscillation of the speaker case. This engine, with its movement back and forth, is responsible for the variation of volume and intensity of the vibrations. When the volume is increased, the oscillation becomes more intense, generating a more powerful sound. The engine is connected to a conewhich is pushed forward by the movement of the engine itself. This Movement transforms electricity into pressure wavesthat is, sound waves that travel through the air.
How a speaker is made and what it is for
The engine consists of two fundamental elements: one mobile coil and a magnet. These two components interact with each other thanks to the phenomenon ofelectromagnetismgenerating movement. Electromagnetism is a physical principle according to which a body crossed by an electric current generates a magnetic field. In the case of the engine, the coil is surrounded by a copper wire inside which electricity flows. This current flow produces a magnetic field that interacts with permanent magnet – a common magnet – creating the movement of the coil. The attraction and repulsion of the coil are influenced by the intensity of the electric current: the greater the current that crosses the wire, the stronger the magnetic field generated. In addition, inverting the direction of the current, the reversal of the magnetic field poles is also obtained. This mechanism allows the coil to swing back and forth in response to the changes in intensity and current direction. The most incredible thing is that this current flow that crosses the copper wire is a sort of “coal copy” of the registered passage. For example, in a musical recording containing instruments such as battery, bass, guitar and violins, the variation of the electric current faithfully reproduces the characteristic vibrations of each of them. It is the same mechanism as the vocal cords: we manage to emit a sound by making them vibrate, and so it is for the case, which vibrates in response to the electrical signal that comes to it. But once we have this vibration so faithful to our song, how does it propagate in the air?
The sound waves propagate in the air
One of the fundamental principles of sound reproduction concerns the functioning of the cone of the speaker, which is connected to the coil via two cables. Each vibration generated by the engine is thus transferred to the cone, which moves back and forth, generating pressure changes in the air. These variations, commonly known as sound waves, spread in the environment until we reach our ear. But how do the sound waves be perceived as music? We must start from an assumption: The air is an elastic vehicle. This means that, similarly to an elastic in tension, the air can be compressed and subsequently return to its original condition. When the sound waves spread, the air particles suffer small oscillations, moving and quickly returning to their initial position. The speakers, therefore, exert pressure on the air molecules, pushing and pulling them into an oscillatory movement that is transmitted through the atmosphere with a chain effect. This process continues to reach the human ear. In the ear the sound waves hit the eardrum, making it vibrate. These vibrations are then converted into electrical signals, which travel along the acoustic nerve to the brain. Finally, it is the brain that interprets these signals and translating them into the perception of sound, allowing us to recognize words, music and other environmental noises. This extraordinary mechanism shows how a simple physical phenomenon can be the basis of one of the most complex and fascinating sensory experiences of our daily life.
How is it possible to play sounds simultaneously?
One might think that a sound wave can represent only one sound, but how is it possible that in a song they live multiple sounds in the same wave in a simultaneously? When A single musical instrument emits a sound, generates a sound wave. However, this is not a simple wave, but one combination of multiple waves overlapping. The predominant vibration corresponds to the main note, but it is accompanied by a series of secondary vibrations. These multiple frequency layers contribute to determining the stamp of the instrument, i.e. that distinctive quality that allows you to distinguish, for example, the sound of a trumpet from that of an harp, even without seeing them. When multiple instruments play simultaneously, as happens in a piece of music, an even more complex wave is created. Each tool adds its own frequencies to the overall wave, with some frequencies that strengthen each other, while others mix making themselves less distinguishable. This complex wave form can be reproduced by speakers of any size, from the powerful speakers of an amplifier to the tiny speaker inside the headphones. Regardless of the size of the reproduction device, the physical principle behind the sound remains unchanged: the speaker vibrates in order to faithfully recreate the sound waves, allowing us to listen to the music as it was recorded. The apparent simplicity of the sound that we perceive celas, therefore, an extraordinary physical and harmonious complexity, the result of the combination of numerous frequencies that give life to the musical experience.
