Category Sound

How does Recording happen?


 To record sound, the pattern of vibrations in the air must be turned into a form that can be stored. The gramophone was the first sound-recording device. To record, the sound was made to vibrate a needle, which cut a wavy groove in a foil surface. To play back, the needle moved along the groove, making a diaphragm vibrate to reproduce the sound. In the electric gramophone, introduced in the 1920s, the vibrating needle created an electrical signal, which was amplified to drive a loudspeaker.

The first type of gramophone was the phonograph, invented in 1877 by the American inventor Thomas Edison.

Tape recording was developed in the 1940s. To record on to tape, the electrical signal from a microphone is sent to an electromagnet, which creates a pattern in the tiny magnetic particles that coat the tape. This pattern recreates the signal as the tape plays, and the signal is amplified before going to a speaker.

Most sound recording is now done digitally. A microphone turns the sound into an analogue electrical signal, which is then digitized more than 44,000 times a second to create a long string of binary numbers. The binary numbers can be stored in a computer’s memory or disc drives, or on a compact disc (CD). On a CD, the binary digits 0 and 1 are represented by flat areas or shallow pits in the surface. In a CD player, these are detected by a laser as the disc spins and reflected to a light-sensitive device. Electronics rebuild the original electric signal, which is amplified and sent to speakers. Computer CD-ROMs and DVDs work in the same way.

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How would you distinguish between Pitch and Volume of Sound?


Sound has two important features. One is pitch. A low-pitched sound is deep, like a roll of thunder or a booming big drum. A high-pitched sound is shrill, like a snake’s hiss or the tinkle of a triangle. Pitch depends on the frequency of sound waves – the number of waves per second. High-pitched sounds have high frequencies.

Some sounds are so high-pitched that our ears cannot detect them. They are known as ultrasounds. Many animals, like dogs and bats, can hear ultrasounds.

The second important feature of sound is its loudness or volume. Some sounds are so quiet that we can only just hear them, like a ticking watch or the rustling of leaves. Other sounds are so loud, like the roar of engines or the powerful music in a disco, that they may damage the ears. Sound volume, or intensity, is measured in units called decibels (dB). Sounds of more than 80-90 decibels can damage our hearing.

            An ultrasound scanner beams very high-pitched sound waves into the body. The echoes are analyzed by a computer to form an image, the baby in the womb.

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What do you know about Sound?


One of the most familiar forms of energy in daily life is sound. We hear natural sounds like birdsong and wind. We hear the noise of vehicles and machines, and sounds such as speech and music from radios, televisions and stereo systems. We also rely on sounds to communicate when we talk to others.

Sounds are made by objects that vibrate (move to and fro rapidly). As an object vibrates, it alternately pushes and pulls at the air around it. The air is squashed and stretched as the molecules of the gases in air are pressed close together and then pulled farther apart. These are regions of high and low air pressure. They pass outwards away from the object in all directions. They are called sound waves.

Sound waves start as the energy of movement in the vibrations. This is transferred to the energy of movement in air molecules. As the sound waves spread out they widen and disperse, like the ripples on a pond after a stone is thrown in. So the sound gradually gets weaker and fades away. However if there is a hard, smooth surface in the way, such as a wall, then some sound waves bounce off it and come back again. The bouncing is known as reflection and we hear the returning sound as an echo.

Sounds also travel as vibrations through liquids, such as water, and solids, such as metals. The atoms or molecules are closer together in liquids than in air, and even closer still in solids. So sounds travel through them much faster.

            An object that vibrates to produce sound waves is a sound source. A bow rubs over the cello’s string and makes it vibrate. The vibrations pass into the air and also to the cello’s hollow body making the sound louder and richer.

The speed of sound varies depending on the substance it travels through. Atoms in steel are closer than molecules in air, so the vibrations of sound move faster and further.

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What does the word bass mean?

          Like treble, bass too describes a range of sound in terms of tone quality as well as musical notes. But they are opposite voices.

          Bass defines tones of low frequency, pitch and range from 16-256 Hz. Hence, it forms the lowest part of the harmony in songs. If we increase the bass up in a note, we get a deeper sound. On the other hand, if we volume up a treble, we get a higher sound.

          In choral music, bass is provided by adult male bass singers, while in an orchestra, the lines are played by the double bass and cellos, bassoon or contrabassoon, low bass such as the tuba and bass trombone, and the timpani or kettledrums. In popular music, the bass part or the ‘bassline’ provides a rhythmic support to the band.

           The main bass instruments used by musicians are keyboard bass and bass drum. 

Why is it said that a tuning fork gives a clear example of natural frequency?

            We know that all objects in the Universe have their natural frequencies. Some may be simple but some, complex. A renowned example for an object with a simple natural frequency is the tuning fork. It is an acoustic resonator that appears as a two-pronged fork with the prongs or tines formed from a U-shaped bar of elastic metal like steel. Depending on the length and mass of the two prongs, the fork produces a pitch. Generally, it is used as a standard of pitch to tune musical instruments.

            As mentioned earlier, a tuning fork has a natural frequency. When set vibrating by striking against a surface, or by an object, the fork resonates at a specific pitch and emits a musical tone once the high overtones have died out.

            Traditionally, the forks have been used to tune musical instruments. But today, electronic tuners are replacing them in applications.

            The tuning fork was invented in 1711 by British musician John Shore, who was a trumpeter and lute player. 

How does a synthesizer work?

           Synthesizers are one of the most important musical instruments today. Although they look like small electronic pianos, the uses of synthesizers are much more than one can imagine.

           Technically, it is an electronic keyboard that can generate or copy, any kind of sound. For instance, it can mimic the sound of a traditional instrument like a violin or piano, or create brand new sounds like the crunch of footsteps on the surface of Mars!

           The very meaning of ‘synthesize’ is to make something new, often by putting together things from existing pieces. This is exactly what the synthesizer instrument does. It has got a number of oscillators or sound tone generators, each of which can produce waves of different shapes. They combine the waves to make complex sounds. Depending on this combination, the sounds vary, and mimic existing instruments.

             Based on how they function, synthesizers are classified into analogue and digital.

             The changes caused by synthesizers in the field of music are unparalleled. Since the 1970s, they have been used in popular music, and today, there is no pop record made without featuring an electronic keyboard of this kind. 

Why is a mixing console an important unit?

Mixing console is a device that used for mixing and changing the volume, and dynamics of audio signals. The sources of these signals could be many- microphones used by singers, or mics picking up the beats from drums.

The device is known by different names like audio mixer, audio console, or mixer.

There are numerous applications for which a mixing console is used. For instance, it is commonly used in recording studios, public address systems, sound reinforcement systems, musical concerts, broadcasting, television, and film post-production.

Let’s look at a few of its applications in detail. When two singers are singing, say a duet, a mixing console combines signals from the two microphones into an amplifier that drives one set of speakers. Then, during a live performance, the signals from the mixer go directly to an amplifier plugged into speaker cabinets.

Almost all bands use a mixer to combine musical instruments and vocals. This mix can then be amplified through a public address system.

Radio broadcasts too use it in order to select audio from different sources like CD players, and in-studio live bands. 

Why is it said that the telephone is an important invention?

          The telephone is a communication tool that has become an integral part of human life since its invention in 1876.

          Technically, it is a device that transmits voices over a distance, using a wire or radio. The transmission is made possible by converting sound signals to electric signals.

          There are many reasons why the device is important to us. The first and foremost reason is that it enables communication without the hassle of travelling far.

             It is perhaps the cheapest mode of communication that facilitates talking to a person abroad at a relatively fair price. Hence, the device has played a major role in better socialization and interaction among people.

            Although it was originally meant for voice communication, telephones have evolved over the years. From wired phones emerged mobile phones that could be used anywhere.

Why is it said that the telephone is the end result of many other inventions?

             The telephone that we see around today was certainly not the first model developed for communication. Prior to its invention, many people had attempted to make different types of phones. However, Graham Bell’s telephone, invented in 1876 was the most successful.

             Most of the earliest models were mechanical acoustic devices that transmitted speech over a distance greater than that of normal speech.

             One important discovery during the 17th century was by Robert Hooke. He made an acoustic string phone in 1667. By the 19th century, various types of telegraphs were developed. It was after improvements of the electrical telegraph that the telephone emerged.

             There were many people who worked on this invention. However, it was Alexander Graham Bell, who won the patent for the device. 

What is meant by sound recording?

          Sound recording and reproduction refers to the inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects.

          The inscription could be electrical, mechanical, electronic or digital in nature. The earliest method of music reproduction was done through mechanical systems.

          Today, there are two main classes of sound recording technology – analogue recording and digital recording.

               Acoustic analogue recording is done with the help of a microphone diaphragm that can detect and sense the changes in atmospheric pressure caused by acoustic sound waves. It then records the waves as a mechanical representation on a medium such as a phonograph record.

              In digital recordings, analogue signals picked by a microphone are converted to a digital form by a process called digitization.

              The first all-digitally-recorded popular music album, Ry Cooder’s ‘Bop till You Drop’ was released in 1979.