One of the few compulsory gadgets that every doctor carries is the Stethoscope. A sophisticated assembly constructed out of steel and plastic, stethoscope is an age-old source to diagnose cardiac problems. Popularly known as “Doctor’s Weapon”, stethoscopes have seen innumerous changes in their structure and working since their invention in 1824. Models that can be tuned with a smart phone (yes, really!) have already hit the market. Peculiarly, almost every type of stethoscope has found its space in the vast world of medical experts. There’s one for a cardiac for example, a different one for a pediatrician and yet another for a physicist. This Insight covers one of the most popular types of stethoscopes: Littmann Stethoscopes, which you may recognize as the serpentine devices hanging around doctors in movies. These stethoscopes are one of the oldest species and are still recommended for their precise results. 

How loud can you shout to make yourself heard at a distance? How large is that distance? A hundred meters, a kilometer, is that it? What if you were to talk to peopleseparated by miles, could you shout that loud and kill your lungs? Or you’d rather whisper into an adjacent ear, and be heard at some other location, no matter the distance, and perhaps irrespective of time? An electronic ear that couldhelp store and transmit your voice and sound at light speeds and even ramp it up if you are too frail? Yes, such is the microphone!But how does a microphone achieve such a feat? How does it follow our rhythmic and unpredictable sounds and change them into electrical signals?Let us find out how by peering into one such device, the dynamic microphone.

Earphones/Earbuds have been assisting mobile gadgets since the invention of walkman. Though they account for hardly a few percentage of the cost of the entire device but their evolution over the time has never been an easy challenge for the engineers. Shape, size, comfort and sound quality are the key parameters while designing an earphone.  From morning walk to making long journeys pleasant, ear phones cannot be kept out of the daily life.Technically speaking earphones falls in the category of transducers that convert electrical energy into sound energy.  Undoubtedly, over the years companies have been adding more and more complex features in the earphones to improve the listening experience of the users.  In this article we will explore more about the earphones. 

Piezo buzzer is an electronic device commonly used to produce sound. Light weight, simple construction and low price make it usable in various applications like car/truck reversing indicator, computers, call bells etc. Piezo buzzer is based on the inverse principle of piezo electricity discovered in 1880 by Jacques and Pierre Curie. It is the phenomena of generating electricity when mechanical pressure is applied to certain materials and the vice versa is also true. Such materials are called piezo electric materials. Piezo electric materials are either naturally available or manmade. Piezoceramic is class of manmade material, which poses piezo electric effect and is widely used to make disc, the heart of piezo buzzer. When subjected to an alternating electric field they stretch or compress, in accordance with the frequency of the signal thereby producing sound.  

Transducers are devices which convert energy from one form to other. A microphone is a transducer which converts sound energy to electrical signals. It works opposite to a speaker. Microphones are available in different shape and sizes. Depending on the application, a microphone may use different technologies to convert sound to electrical signals. Here we are going to discuss about the Electret Condenser Microphone which is widely used in mobile phones, laptops, etc.Electret Condenser Microphone, as the name suggests is a parallel plate capacitor and works on the principle of a variable capacitance. It consists of two plates, one fixed (called the back plate) and the other moveable (called Diaphragm) with a small gap between them.  

Technically we can define speaker, as a component which converts the electrical signals into the equivalent air vibrations to  make audible sound. To understand the working of a speaker, we first need to understand the concept of sound. A sound is nothing but vibrations in air particles.  When a sound source generates a sound, it generally makes a vibration in its surrounding air particles which finally reaches to our eardrum. Sound is characterized by the parameters like frequency, speed, fluctuation, pressure, etc. The speaker works on the same concept. The speaker works on the same concept. It produces vibrations in air particles in order to generate a sound. Let’s have a look to its outside formation