Category Sound

            For deep vibrations and low frequency sounds waves to travel thousands of kilometres under deep sea, there has to be some path to save them from diminishing. Else, a phenomenon like whale communication will never be complete. It is in this context that the SOFAR channel gains relevance. Technically, it stands for Sound Fixing and Ranging and allows low-frequency sound to travel great distances.

            Let’s try to understand the concept better. Some of you might know that sound waves are highly dependent on medium, salinity, temperature and density. That is, at different pressures or temperatures, the waves will travel at different speeds. At a lower temperature in water, the waves move slowly, but at a higher pressure, they speed up. This causes the phenomenon in a level of the ocean called the SOFAR layer or channel.

            The advantage of this channel is that it allows sound waves to move without dissipating much of their energy. And if there is no energy drop, it means a wave can travel longer distance. 

          The howler monkey is a large type of monkey that can be spotted in the rainforests of South and Central America. Its strange name comes from the fact that its calls are louder than any other types of monkeys.

          There are quite a few kinds of sounds produced by the howlers. This includes loud grunts, roars, and barks and of course, howls. The monkeys are most vocal at dawn and dusk. A troop’s cries give information about their size and location.

          Now you may wonder how loud howler monkeys are. In fact, they are believed to be the loudest animals in the world. When a troop gets together and start howling, barking and grunting, the sound can be heard up to 4.8 kilometres away!

          What helps them produce such loud calls is the hyoid bone. This is a structure located near the neck that looks like a horseshoe in humans, but in howler monkeys, they are larger and more cup-like. It allows the animal to produce a single roar that lasts for about 8 seconds. 

            Drums are percussion instruments that have a thick membrane or skin, stretched tightly over its hollow body. They have been used for a long time, and are played with sticks, mallets, or hands. When the instrument is struck, the skin gets pushed down. It then starts vibrating, going up and down multiple times in a second. When this vibration pushes the air, sound waves are created.

            There are many factors that affect sound production in drums. If the head portion of the instrument is large, it produces a low-pitched sound. With a large body, drums absorb higher frequency sounds, while amplifying lower frequencies. As a result, a warmer tone will be produced. If the body is small, the sound generated will be sharp and bright.

            Another important consideration is the volume of air inside a drum. The higher the volume, the lower will the notes be. A further factor is the way with which the instrument is struck. 

              Wind instruments are those musical instruments that produce sound when air is blown into or across its mouthpiece. There are a variety of them used by musicians since time immemorial. The list includes flute, saxophone, clarinet etc. Many of them look similar with long tubes of various sizes and metal keys that cover the holes when played to make notes. In general, bigger instruments produce low pitched sounds.

               Depending on the material with which they are made, wind instruments are divided into two- brass instruments and woodwind instruments. In the former, sound is produced when the player’s lips vibrate, which in turn causes air inside the instrument to vibrate too. Examples of this are horns and trumpets.

              In the case of woodwind instruments, there are different ways with which sound is generated. Let’s look at an example of the most popular one- the flute. Here, an amount of air is gradually blown through the small mouthpiece. When this column of air gets trapped within the instrument, it vibrates, and produces the beautiful sound. There are of course factors that influence the final output.

          String instruments are those which make notes by vibrating. The best examples are the guitar, violin, piano etc. To play them, one has to make the strings vibrate by striking, plucking or rubbing a bow against them.

          Generally, string instruments have something called a sound box or resonator, which amplifies the sound. Each of them, however, works in their own way. For example, a guitar produces sound when the player plucks the string, either using a finger, or a piece of plastic called plectrum. The length of the string is fixed, and controlled by the player himself.

          There are different factors influencing sound in a string instrument, and the most important ones are length, weight, and tightness. If the strings are long, the vibration created would be slower, making lower sounding notes. 

            Electronic music generally refers to music created using electronic equipment. That is, any sound created by the means of electrical signals could be called electronic.

            Production of such music involves the use of power amplifiers as well as loudspeakers. Instruments such as synthesizer and electronic organ are examples of this. In these, oscillators produce electric signals with same frequencies as musical notes. The signals are then pushed to loud speakers. Subsequently, they cause the loudspeaker to vibrate, and produce musical sounds.

            History records that the earliest electronic equipment was invented sometime in 1897. It was called the teleharmonium, believed to have been developed by Thaddeus Cahill. But since it weighed around seven tonnes, the instrument was inconvenient for use. The first practical electronic musical instrument is considered to be the theremin, invented by Leon Theremin in 1919 – 1920. Since then, many more equipments have been developed till date.