1.The sound: definition & graphic representation

DEFINITION

Sound is an hearing sensation produced by a vibration transmitted through a sound medium (solid, liquid and / or gaseous).

There are three things that are necessary for sound to exist:

A source that produces sound

2. A medium that transmits vibration.

3. A receiver: the ear and the hearing.

The Sound Waves

Sound waves are the way of propagation of a vibration in an elastic medium (a solid medium, liquid or gas). They can be represented through drawn sinusoidal waves.

PARTS OF A SOUND WAVE

CREST & trough

The section of the wave that rises above the undisturbed position is called the crest. That section which lies below the undisturbed position is called the trough. These sections are labeled in the following diagram:

amplitude

The term amplitude can have slightly different meanings depending upon the context of the situation.

Its most general definition is that the amplitude is the maximum positive displacement from the undisturbed position of the medium to the top of a crest.

In some discussions it is important to distinguish between positive and negative amplitudes. These displacements are shown in the following diagram

wavelength

This is the distance between any two adjacent corresponding locations on the wave train. This distance is usually measured in one of three ways: crest to next crest, trough to next trough, or from the start of a wave cycle to the next starting point.

frequency

Frequency is often not termed as a part of a wave, but it makes sense to introduce its meaning in this section.

Frequency refers to how many waves are made per time interval. This is usually described as how many waves are made per second, or as cycles per second.

The unit Hertz is abbreviated this way:

1 Hertz = 1 Hz

TASK 1. LABEL THE SOUND WAVE (Google Classroom)

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