How do Smartphone Speakers Work

How do Smartphone Speakers Work

How do Smartphone Speakers Work
How do Smartphone Speakers Work
How do Smartphone Speakers Work, play your music, and project the voices of your friends and loved ones? A smartphone speaker does this, all while being only the size of a dime. To understand how this tiny marvel of engineering can do so much, we will first look at what it is made of. Most smartphones have two speakers. 

A smaller speaker near the top of the phone is used for phone conversations while a larger one at the bottom is used for playing music and other louder applications. Although this second speaker is the larger of the two, it is still ridiculously small. It weighs as much as a dime and is about equal in size. 

The smaller speaker weighs a fifth of that! Let’s focus on the top speaker as both the top and bottom speakers have the same components with identical functions. In a smartphone speaker, there are 4 key components. A diaphragm, a voice coil, a magnet, and a spider. Four additional components, two-pole plates, the plastic case, 

and the front cover, provide uniformity for the magnetic field, structural support, and protection. Let’s focus on the 4 key components and go over them in detail. The first key component is the diaphragm. It is a thin piece of rigid plastic that moves back and forth to generate sound waves. 

The diaphragm moves forward and compresses air particles generating a high-pressure wave, and then moves backward and generates a low-pressure wave. The diaphragm can do this thousand of times a second which creates cycles, or oscillation, 

of high pressure and low-pressure waves. These waves then propagate out from the speaker and when this oscillation of high pressure and low-pressure waves hits our ears, it is perceived as sound. The diaphragm creates these waves by moving back and forth, and what facilitates this movement is the second component, the voice coil. The voice coil is firmly mounted to the diaphragm and it is constructed from a coil of insulated copper wire. 

The diaphragm and coil are positioned around the third component, the magnet. In a smartphone, this magnet is made of neodymium which has a strong permanent magnetic field. Together, the coil and neodymium magnet act as a kind of miniature motor. When a current is applied to the coil, a magnetic field in the coil is generated or induced. The interaction between the coil’s temporary magnetic field and the neodymium’s permanent magnetic field causes the coil and the diaphragm to move. When the amount of current running through the coil changes, it also changes the shape of the coil’s temporary magnetic field. This in turn changes the position of the coil and diaphragm. 

Thus, when a waveform of current like this is run through the coil, the diaphragm will move accordingly, and the pressure waves generated by the diaphragm will result in the corresponding sound waves. The fourth key component is the spider. This thin piece of flexible saran wrap like plastic stabilizes the diaphragm and prevents it and the voice coil from moving side to side. The spider functions are similar to the springs of a trampoline. Both the trampoline’s surface and a diaphragm are free to move up and down, 

but not side to side. The spider, similar to a trampoline, applies to counteract tension to the direction of motion, thereby returning the diaphragm to a central position. If the diaphragm and voice coil weren’t stabilized, they could hit the magnet resulting in both getting damaged. To summarize, the diaphragm physically pushes on the air in order to generate sound waves. This diaphragm is mounted to a voice coil and is stabilized in the center by the spider. 

Finally, the voice coil and magnet operate as a miniature motor to drive the diaphragm. Working together, these 4 components generate an impressive variety of sounds from our smartphone. Branches of this episode will continue to explain: what are sound waves, how does a coil with a magnet result in such a complex motion, how do our ears perceive sound, and if the sound is a movement of air particles.

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