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2WHAT IS ACOUSTICS?
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Acoustics is the science of sound, including its production, propagation, and effects. Various branches of acoustics are bioacoustics, physical acoustics, ultrasonics, and architectural acoustics. But for one to actually understand what acoustics is, one must understand its fundamental component, the sound wave.
What is a Sound Wave?
Sound itself is defined as any disturbance that travels through an elastic medium such as air, ground, or water to be heard by the human ear. In terms of physics though, sound is considered to be the waves of vibratory motion themselves, whether thy are heard or not. Sound is created through vibrations, when a body moves back and forth. These oscillations cause a periodic disturbance of the surrounding air or medium that flows outward in straight lines in the form of a pressure wave. The effects of these waves on the human ear are what we perceive as sound.
Characteristics of Waves
All waves have a period, frequency, and wavelength. The period is the time it takes for a wave to go through one complete oscillation. The frequency is the number of complete oscillations the wave makes in a second. Lastly, the wavelength is the spatial distance over which the wave makes one complete oscillation. The frequency of a sound wave is measured in hertz or Hz, the wavelength is measured in meters, and the period is a measurement of time, which is usually seconds.
Hearable Sound
Hearable sound is defined as the range between 20 - 20,000 vibrations per second. Waves below 20 vibrations per second are called subsonic sound, and correspondingly the waves above 20,000 vibrations per second are called ultrasonic.
Musical Sound
What is musical sound? Musical sound is sound that is distinguished by certain characteristics. These characteristics are pitch, intensity, and quality. Pitch is the characteristic which describes how high or low a tone is. A high or low tone depends on the rapidity in which a sound boy vibrates. The higher the vibrations the higher the pitch and visa versa. The intensity, also known as the loudness, is changed by the amplitude of the vibration. The amplitude is measured in decibels. Lastly quality, or timber, is the bases of harmonics. Harmonics deals with the different qualities given of sound waves produced by different vibrating bodies.
Interesting Fact of Sound
Have you ever wondered why sound "sounds" clearer at night? The answer has to do with sound wave refraction. It turns out that sound will refract towards cooler temperatures. Thus in the day time the air, which is the medium which sound waves travels through, is warmer and the waves are inclined to travel towards the sky, as shown in figure four. But, in the night time the air is colder near the ground and the waves refract more horizontally then vertically, as shown in figure five. Thus sound is easier to hear farther away in the night time then it is in the day. Cool stuff hu?!?!
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