Mechatronic Engineer

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-------------------------Rohan’s part---------------------------------------------- Headphones are a duo of small loudspeakers that are designed to be held in close proximity to the operator’s ears. Their primary function is to allow audio to be played directly from these loudspeakers to the user’s ears allowing individuals to keep a certain amount of personal privacy whilst enjoying/working in public and simultaneously reducing/blocking surrounding ambient noises. They are powered through an external power source, which also provides the audio current which is transformed into sound energy. Headphones either utilize wires for connection to the signal source (e.g. radio, mobile phones or portable media player), or have a wireless receiver which picks up signal without the need for a cable. They have also been designed to be user-friendly and safe. ----------------------------------------------------------------------------------------- --------------------Kevin’s part----------------------------------------------------

The headphone operates via the oscillation of a mounted coil submerged in a small magnetic field. When an electric current is passed, the induced movement in the coil will vibrate in accordance to the current and produce sound. The magnets must be designed a specific strength and produce a certain amount of magnetic flux such that it can operate within the variable volume range. The coil itself and the wires which attach the main speaker cones in the headset to the power source must be made of a ductile, conductive material. It needs to be moderately ductile such that it does not fracture as stress is applied to it via induction.

The diaphragm is attached to the coil and oscillates inside a cone. Here the changing air pressures vibrate the surrounding air generating what we perceive as sound. As such, it is imperative that the diaphragm be made of a material durable enough to withstand cyclical fatigue and be strong enough to withstand cracking. It is required to have a relatively high yield strength so when it is put under the cyclical and tensile stress, the material used does not stretch or neck, which would result in distortion of sound. The diaphragm also needs to be of a specific size, )depending on the voltage delivered) such that the strain does not distort the sound.

The headband of the headphones itself must haves a high yield strength as it will constantly be stretched out to be placed on the head. The material used will need a relatively high melting point to withstand any creep, as the band will be put under tensile stress for prolonged periods of time (as it remains stretched on the head). It needs to be tough enough to withstand small forces so cracks are not formed. The headphone casing as a whole must be ergonomically friendly to the user as well as optimize maneuverability while mounted to the head.The ear muffs/buds should either fit comfortably around the ear or inside the ear canal to deliver sound directly to the ear drum. The casing acts as the overall frame and will undergo excessive use, being taken off and on the head. It is essential that this be made of a sturdy material resistant to fracture.

Surrounding the headphone section of the ear muffs should be an appropriate soft material. This is primarily used for padding for the users ears and provides an ergonomically friendly way to deliver sound. Along with being soft, the padding will need a very high yield strength as it is compressed due to the stress provided from the elasticity of the headband and the wearer’s head.

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(Wonho’s part)

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------------------------Cage’s part---------------------------------------- Headphones have become an indispensable part of our lives. To understand the materials of headphones, our group wants to discuss the speaker...
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