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Unformatted text preview: Unit 2. Lesson 1. Introduction to Marine Mammals and Acoustics Lesson Objectives: • Introduce basic acoustic principles and the movement of sound through air and water. • Students will gain an understanding of the importance of the study of acoustic oceanography. • Students will gain an understanding of why and how marine mammals use sound. Vocabulary: sound, acoustics, medium, amplitude, pitch, frequency What is Sound? Sound has many definitions. The most familiar one is a noise, vocal utterance, or musical tone. Although most ideas of sound center on something that is heard by the human ear, it can have many other definitions. For example, it can mean secure and reliable. It can also mean a relatively narrow passage of water between larger bodies of water and also a body of water between the mainland and an island. Much can be learned from studying sound. The military uses sound to locate ships and submarines in the water, researchers use sound to study the ocean floor, biologists use it to track marine mammals and study the ocean floor (topography). Sound is used to help make medical diagnoses. Ships used sound to avoid obstacles under the surface of the water. The study of sound is called acoustics . ©PROJECT OCEANOGRAPHY FALL 2000 SOUNDS OF THE SEA Introduction to Basic Acoustics Acoustics is the science that deals with the creation, spreading and delivery of energy in the form of vibrational waves in air, water or other medium . Sounds begin as a vibration that is transferred through a medium in a series of waves. Sound waves travel with certain intensity called amplitude. When the amplitude of a sound increases, the intensity of the sound increases, as does the amount of energy that is transferred. Another property of sound is pitch, which is highness or lowness of a sound. The pitch depends on the frequency of the sound waves, or how many waves pass a given point per second. The higher the frequency, the higher the pitch, and the lower the frequency, the lower the pitch. An example of pitch is the roar of a lion and the chirp of a bird. A lion’s roar is a low pitch, while the bird is a high pitch. An understanding of acoustics is necessary to understand the sounds produced by fish and marine mammals in the ocean, how fast and far sound can travel, noise pollution, how energy moves as sound, and the things that interfere with sound signals. How Does Sound Move? The movement of sound is in waves. Amplitude, frequency (f), and wavelength are properties used to characterize waves . Every sound has a unique set of wavelengths and frequencies, which are related to velocity, or the speed at which sound travels. Sound or acoustic energy travels best through solids and liquids....
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- Spring '11
- compressional wave, ©Project Oceanography