Year 12 Recording and Reproducing Sound in Practice

Year 11 Sound Starter

Years 7 – 10 Sounds Sensational

A comprehensive resource for the NSW physics course

The page opens with a very effective animation showing the phase change at an open end from a pressure point of view.

Test your own hearing

Detailed instructions.

Decibels

Uses "P" for Power and 'p" for pressure, but not "I" for intensity so it could be confusing for some students, nevertheless a very thorough website. It also introduces "sones".

Microphone handbook No 1

12 pages of text on different types of microphones.

Microphone handbook No 2

A Shure website with files on an audio guide for music educator that covers everything from recording to live sound reinforcement and will help you choose equipment for a variety of applications;A music studio guide that describes particular microphone techniques and placement, it also includes tips on how to pick up a natural tonal balance, help reject unwanted sounds, and create special effects;W hat happens when a high impedance microphone is connected to a low impedance input?"; Common questions regarding microphone sensitivity ratings and dB SPL input levels; Shure is often asked "How far away will my microphone pick up?" or "Which microphone has the best reach?" Both questions are based on a misunderstanding of how microphones work. This bulletin attempts to debunk the myth of microphone reach;

The Soundry

This is an interactive and educational web site about sound. Covering everything from the most basic concepts of what sound actually is to the specifics of how humans perceive it, the Soundry aims to promote enthusiasm and knowledge of sound. The site was created by US high school students as a ThinkQuest contest entry.

Acoustical Society of America

This site features an Education section that has an extensive list of career sites, as well as some interesting material on the historical development of the wave theory of sound. There are many university sites listed with only a few relevant links to secondary physics.

Street Mozart

A video of a roller skater rolling between two rows of filled bottles, gently hitting them to produce a tune by Mozart.

Tacoma Narrows Bridge collapse

A four minute video on Youtube with occasional commentary.

Ruben's Tube

Standing wave of flaming gas jets, some play music through the tube as well, but in such cases the flames are just a visual volume indicator. None of the videos show the pressure antinodes at the closed ends as they don't have holes there.

Chladni Plate

Several Chladni figures produced by a bow on a square steel plate.

Effect of baffle board

An effective demo, once seen is easily copied at school.

Longitudinal wave applet

Longitudinal wave applet with many aspect to be varied.

Forced Oscillations (Resonance)

This applet by Walter Fendt features a mass on the end of a spring, but with an oscillating driving force at the top of the spring. You can vary the spring constant, the size of the attached mass, the attenuation factor and the frequency of the driving force. You can also show the elongation of the driving force and the mass at the bottom over time. The other graphs on phase, etc. are too complicated for Year 12'. The application has limited use to Sound, but if the attenuation is set to zero, and a few frequencies are chosen carefully then the effect can be dramatic.

Standing Longitudinal Waves

This applet by Walter fendt shows pmoving articles in a column forming standing waves. You have the choice of both ends open, one end open or both ends closed. You can also show the funadamental and overtones up to the 5th. The length of the tube can be varied, and the wavelength and frequency are also displayed. Unfortunately the column has the letters A, N under the positions of the displacement antinodes and nodes, and the applet also shows variation from the displacement point of view, which could be potentially confusing. It is possible to show the air particles on the screen without showing the nodal pattern.

Reflection and Refraction of Waves by Huygen's principle

The applet by Walter Fendt very effectively describes reflection and refraction of waves. It features several stages. First, a straight wave front approaches a boundary at an angle, 2nd as the wave front progressively hits dots on the boundary, circular waves are created on both sides of the boundary, 3rd A repeat of stage 2, but with a line connecting the fronts of reflecting circular waves, and same for the refracting waves, 4th A repeat of stage 3, but with an overlay of the incident, reflected and refracted rays, showing the various wavefronts at right angles to the direction of their ray, 5th this is followed by a series of incident wave fronts. The indices of refraction can be changed, as well as the angle of incidence. There is a text box to explain each stage. Total Internal Reflection can also be demonstrated. A most impressive applet.

Interference of two circular Waves

This applet by Walter fendt shows the nodal and antinodal lines formed by the circular waves from two point sources. You are able to vary the spacing between the sources and the wavelength. You are also able to move a point around the interference pattern and read off the path difference. Slow motion and pause/resume options are also available.