REPORTED BY : CAITLIN SUMI L. DE LEON

The interdisciplinary that focuses on the study of properties of sound, especially its transmission, is called ACOUSTICS. A scientist who works in this field is an ACOUSTICIAN while someone working in the field of acoustics technology is called an ACOUSTICAL or an AUDIO ENGINEER. The science of acoustics relates the production and transmission of sound to our sense of hearing.

The differences between sounds are caused by three factors, namely: intensity, pitch, and tone.

TONE refers to the sound quality. It depends on the combination of different frequencies of sound waves. It is the tone of a vibrating medium that distinguishes it from another source. For instance, a symphony orchestra in Indonesia called GAMELAN is composed of more than 50 musicians playing different kinds of percussion instruments. Playing at the same time, one could identify through its tone the sounds created by each of the instruments.

Imagine Eric Clapton doing an intimate concert during Valentine's Day. As he strums a string, the energy from his finger is transmitted to the guitar string. When the whole string oscillates, we hear a low pitch called FUNDAMENTAL. It has to be noted that aside from the fundamental, the string producing many more pitches.

OVERTONES are parts of the string that are characterized by frequencies higher than the fundamental. HARMONICS, on the other hand, are those vibrating parts in whole number multiples of the fundamental. A frequency of two times the fundamental will sound one octave higher and is referred to as second harmonic. Since the fundamental is one times itself, it is also known as the first harmonic.

PITCH refers to our subjective impression about the "highness or lowness" of a tone, which is related to the frequency of the tone. The sensation of the pitch depends upon the frequencies of the waves received by the ear. A LOW-FREQUENCYvibrating source produces a sound of low pitch while a HIGH-FREQUENCY vibrating source produces a sound of high pitch. Sound waves of the same frequency are said to be in same pitch.

The human ear has an audible range of 20 to 20,000 Hz. Some animals like dogs, birds, and other mammals are more sensitive to sounds because they can hear sounds at even higher frequencies. Sounds that exist below the audible range (below 0.001 Hz-16 Hz) are calledINFRASONIC while those that are too high for us to hear (20,000 Hz above) are called ULTRASONIC.

The INTENSITY of the sound wave refers to the amount of energy that is transported past a given area of the medium per unit time. The greater the amplitude of vibrations of the particles of the medium, the greater the rate at which energy is transported through it, and the more intense that the sound wave is. Based on a DECIBEL SCALE, the smallest audible sound (near total silence) is 0 decibel (dB).

Sound wave is produced by vibrating object. This object could be any musical sound or anything like a ruler that has the ability to oscillate. When the frequency of forced vibrations on the object's natural frequency, a dramatic increase in amplitude happens. This is called RESONANACE. The term literally means "resounding or sounding again"

In order for something to resonate, there should be a force to pull it back to its original position and enough energy to keep it vibrating. This phenomenon can be demonstrated using a pair of tuning forks adjusted to the same frequency placed about one meter apart.Striking one of the forks will create vibrations into the other fork. The motion of the fork is sometimes called SYMPATHETIC VIBRATION.

Resonance is important in musical instrument as it causes the production of sound in these materials. Consider the resonance that occurs in a guitarstring.

Since the collapse of the Tacoma Narrow Bridge in November 7, 1940, this resounding property of materials has been a big consideration in designing buildings and infrastructures. Based on the theories generated from bridge's collapse, now popularly known as "Galloping Gurdy" a 35 mile per hour wind excited the bridge's transverse vibration mode, with an amplitude of 1.5 feet. The bridge then began to oscillate in simple harmonic motion. The amplitude increased and the bridge began to twist until it eventually collapsed after three hours.

In layman's term, the word NOISE means any unwanted sound. In acoustics, NOISE is defined as disturbance, especially a random and persistent disturbance, that obscures or reduces the clarity of a signal. It is characterized as being a periodic or having a non-repetitive pattern. We have learned that waveforms display various characteristics.

As can be seen, two distinct sound wave are produced by two different activities. So the tuning fork has a pure sound thus, it is represented by the regular form of wave, it has a fixed number of vibrations per second. On the other hand, the sound produced by the hammer is irregular and spiky in shape thus noise is produced in this activity.

As there are so many activities that produce irregular patterns of sound waves, noise pollution became one of the major environmental problems that the government and each citizens are facing at present, the word NOISE came from the word NAUSEAS meaning seasickness. Pollution, is the introduction of substances or energies that causes instability, disorder, or discomfort to the ecosystem. Noise pollution is also referred to as the environmental noise.

1. Industrial sources –are those from various industries and machineries working at very high speed and sound intensities.

Some examples are flying aircrafts, bulldozers and trucks

2. Non Industrial sources - includes the noise created by transport traffic, police siren, and whistle and ETC.

1. Noise can lead to deafness. Exposure for more than 8hrs a day to sound in excess of 85 decibels is potentially hazardous

2. Noise disrupts sleeps and causes insomnia.

3. Numerous have documented the heart related, respiratory, neurological, and other physiological effectscaused by noise pollution.

4. Experiments pointed out the fact that noise pollution decreases work efficiency.

5. Noise pollution damage the nervous system of animals. Animals loose their minds and become dangerous.

6. Noise pollution causes poor quality of crops.7. As noise carries energy as transmitted by irregular wave patterns, it can weaken the edifice of buildings, bridges and monuments.

1. Reduction at the source.2. Interruption of transmission paths.3. Protection of the receiver.