# Sound

## Sound Waves

### In the case of sound, the medium is the material that the sound is travelling through, which in most examples will be either in air or water. ## Visualising a Sound Wave

### The image below shows a sound wave as represented by an oscilloscope:- ## Amplitude and Frequency, Pitch and Volume

### 2. Pitch- How high or low a Sound is . In Physics, Pitch is defined as Frequency. ## Volume and the Decibel Scale

### In Physics, the loudness of a sound is measured using the unit - Decibel (dB). The diagram below shows the Decibel scale, with some example sounds:- ## The Speed of Sound

### The speed of sound can be calculated in two different ways within the school. Both are based on the speed calculation seen previously:- ## Measuring the Speed of Sound (Manually)

### By observing a loud distant event, it is possible to measure the speed of sound. This is due to the difference between the speed of light and the speed of sound. The speed of light is so large that for basic experiments in National 5, it can be assumed that light travels instantaneously between places. By observing a distant loud event, the light would reach you before the sound would, allowing the travel time of the sound to be measured. ### Lightning - The flash of a lightning strike reaches your eye, and several seconds later, you hear the rumble of thunder. ## Measuring the Speed of Sound (Computer Aided)

### By removing the human element from the timing by replacing it with a computer, this reaction Time can be eliminated. This will give a much more accurate value for the measured speed of sound. The equipment below can be used to measure the speed of sound in the lab:- ## Measuring Distance using Sound

### Lots of animals can use sound to understand the World around them. Certain animals can use reflected sound to build up an image of where they are, this is called Echo-Location. It is also the principle behind how RADAR and SONAR work. ### If the speed of sound is known, this time period can then be used to calculate distance, using the formula below:- ## Example 1

### In the diagram below, a Bat at point A sends out ultrasonic sound pulses towards an Insect, then detects the reflected sound waves 0.15 Seconds later. 