My Science School

            We already saw how our ears collect sounds from outside and conduct it to the inner parts. The sound waves are at first collected by the outer ear and passed through the ear canal. It then causes the eardrum to vibrate. Subsequently, these vibrations are transmitted to the cochlea by the tiny bones of the middle ear.

             Cochlea is a snail-shaped structure filled with fluid situated in the inner ear. An elastic partition runs from the beginning to the end of the cochlea, splitting it into an upper and lower part. This partition is called the basilar membrane because it serves as the base, or ground floor, on which key hearing structures sit.

              Once the vibrations cause the fluid inside the cochlea to ripple, a travelling wave forms along the basilar membrane. Hair cells sitting on top of the basilar membrane ride the wave. The movement of hair cells eventually results in the formation of electrical signals.

              The auditory nerve carries this electrical signal to the brain, which turns it into a sound that we understand.

            A treble is a tone whose frequency or range is at the higher end of human hearing. In terms of music, it refers to ‘high notes’ or is the highest part in a composition that has three parts.

            The best examples of treble sounds are the tones of guitars, piccolos etc. Both of them are important instruments. They mostly have very high pitched sounds. The frequencies range from 2.048 kHz – 16.384 kHz.

            A treble clef or a G clef is used to notate such high sounding instruments like the violin, guitar, mandolin, flute, oboe, English horn, clarinet, saxophone, horn, and trumpet.

            In sound production, treble control is used to change the volume of treble notes relative to those of the middle and bass frequency ranges.

            An amplifier is a device used to increase or strengthen the power of a signal. They can be seen in audio equipment of all kinds.

            Let’s take the example of a hearing aid. It has a microphone that picks up sounds from all around and converts them to electric signals that constantly changes in strength. Here, an amplifier takes the signals, and boosts it many times before feeding it into the tiny loudspeaker placed inside the ear canal. The sound thus produced is ‘amplified’ before it reaches the person. That means, the duty of the amplifier is to convert a small electric current into a larger one.

     

 

            Depending on their functions, amplifiers can be categorized as weak-signal amplifiers or power amplifiers. The former is designed to deal with exceedingly small input signals. They are used in audio tape players, CD players tec. History notes that the first electronic device that could amplify was the triode vacuum tube, invented by Lee De Forest in 1906.

            Loudspeakers are equipments that we all are familiar with it. By definition, a loudspeaker is a tool that converts an electrical signal into sound waves to provide the most faithful reproduction that is feasible for its design. The most widely used type of loudspeaker is the dynamic speaker. The moving coil principle commonly used today in speakers was patented by Edward W. Kellogg and Chester W. Rice in 1924.

            Depending on the range of frequencies, loudspeakers can be divided into four- subwoofers, woofers, mid-range loudspeakers and tweeters.

            

Continue reading "What is a loudspeaker?"

            Developed in the 1870s by Englishman David Edward Hughes, carbon microphones were the first reliable form of microphones. They were widely used for many years before being replaced by other types that showed better performance.

            Structurally, a carbon microphone comprises carbon granules within a small container that is covered by a thin metal diaphragm. It requires a battery to cause current flow. By compressing and decompressing the carbon, sound waves change the amount of electric current flowing through the wire. This, in turn, creates electrical waves.

            The biggest disadvantage of carbon microphones was that they had a limited frequency and would not reproduce music effectively.

            On the basis of application, microphones can be divided into different types. The three most common ones are – dynamic microphones, condenser microphones and ribbon microphones. Let’s look at them in detail.

            Dynamic microphones are the most common and durable types, well suited for live sound. They work on the principle of electromagnetic induction, but take loud signals to move the coils.

            The next type of microphones is condensers. They use electrically charged capsules that are far more sensitive than moving coils of the dynamic mic.

            There are both large diaphragm condenser mics and small diaphragm condenser mics. The former is best suited for recording vocals, while the latter is great for high frequency instruments like acoustic guitar and cymbals.

            Ribbon microphones use corrugated metal ribbons that vibrate when pushed by air. But today, they are no longer popular. There is also a microphone known as the piezoelectric microphone. It uses a crystal of piezoelectric material to produce sound.

 

            A microphone, popularly called a mic, is a device we are all familiar with. It is in fact a part of our daily life and can be seen in almost all equipment around us. For example, computers, telephones, televisions, transmitters for commercial radio, tape recorders, hearing aids and public address systems for concert halls, all of them uses microphone.

            Technically, a microphone is a device that converts mechanical energy waves or sound into electrical energy waves.

            Let us see how the device works. When we speak, sound waves carry energy toward the microphone. Inside it, there is something called a diaphragm, which moves back and forth when hit by the waves. As a result, the coil attached to the diaphragm too moves back and forth. This results in the production of electric current, which flows out from the mic to an amplifier, or a sound recording device. Subsequently, the voice of the speaker is heard a loud. This is how personal address systems, electric guitars amplifiers etc. work.