written by
Kyle Forinash and Wolfgang Christian
Sound: An Interactive eBook consists of 33 interactive simulations which require the reader to click buttons, move sliders, etc. in order to answer questions about the behavior of waves and sound in particular. There are also dozens of links to YouTube videos and other online resources that pertain to the topics being covered as well as suggestions for laboratory exercises and sound clips for understanding the fascinating subject of sound and music. The goal is to create an engaging text that integrates the strengths of printed, static textbooks and the interactive dynamics possible with simulations to engage the student in actively learning the physics of sound. Brief introductions to physics concepts are provided as they are needed (and can be skipped if they are familiar to the reader). There is a little bit of algebra involved but not much.
44 supplemental documents are available
Introduction to Sound
Sound: An Interactive eBook consists of 33 interactive simulations which require the reader to click buttons, move sliders, etc. in order to answer questions about the behavior of waves and sound in particular. The goal of this book is to create an engaging text that … download 205kb .zip Last Modified: December 19, 2017
Basics: Work and Energy
In this chapter various physics concepts and definitions needed for the study of sound, acoustics and musical instruments are presented. download 1096kb .zip Last Modified: January 24, 2019
Basics: Molecular Basis of Matter
This simulation shows particles interacting with a slight attraction which will cause them to stay connected with each other to form a a solid at low temperature. But if they have enough thermal energy they will begin to move around each other to act like liquid. … download 1011kb .zip Last Modified: January 17, 2018
Vibrations
All sound starts with something that vibrates. The reed in a clarinet vibrates, the vocal cords in a singer's throat vibrate, the air flowing over the mouthpiece of a flute oscillates, and the speaker cone on your stereo or in an ear-bud vibrates. In this chapter we … download 590kb .zip Last Modified: February 16, 2018
Resonance
Resonance occurs in an oscillating system when the driving frequency happens to equal the natural frequency. For this special case the amplitude of the motion becomes a maximum. An example is trying to push someone on a swing so that the swing gets higher and higher. … download 1285kb .zip Last Modified: February 16, 2018
Resonance Springs
This simulation shows five different masses, each attached to a spring of the same stiffness. The springs are mounted on a mechanical device that shakes the springs and attached masses. download 1253kb .zip Last Modified: February 16, 2018
Quality Factor
Many systems, including musical instruments, have a wide range of frequencies at which the system will resonate. How does this range depend on the damping coefficient? download 1249kb .zip Last Modified: February 10, 2024
Transverse Waves
Transverse waves are the type of wave you usually think of when you imagine a wave. The motion of the material constituting the wave is up and down so that as the wave moves forward the material moves perpendicular (or transverse) to the direction the wave moves. download 917kb .zip Last Modified: March 28, 2022
Longitudinal Waves
Longitudinal waves are waves where the motion of the material in the wave is back and forth in the same direction that the wave moves. Longitudinal waves are sometimes called compressional waves. Sound waves (in air and in solids) are examples of longitudinal waves. download 708kb .zip Last Modified: February 16, 2018
Other Waves
If you stretch a slinky out between two points and gently twist it at one end, the twist will travel down the slinky as a wave pulse. This is an example of a torsional wave. download 634kb .zip Last Modified: January 13, 2018
Electromagnetic Waves
This simulation shows an oscillating electron in a sending antenna on the left. Because electrons have an electric field, an accelerating electron will create a wave in the electric field around it. Magnetic fields are created by moving charges so a magnetic wave is … download 784kb .zip Last Modified: January 3, 2018
Wave Speed
There are two different speeds involved with describing a wave. In previous chapters we saw that the individual points on a wave oscillate (up and down for transverse waves, back and forth for longitudinal waves) with simple harmonic motion, just like masses on … download 1460kb .zip Last Modified: June 17, 2022
Mirrors and Reflection
In many cases waves of all types will travel in a straight line, reflecting off of objects and surfaces at the same angle that they strike the surface. This is called the law of reflection and is true for sound waves as well as light as long as the surface is smooth relative to the wavelength. download 1484kb .zip Last Modified: January 22, 2018
Refraction
A wave that changes speed as it crosses the boundary of between two materials will also change direction if it crosses the boundary at an angle other than perpendicular. This is because the part of the wavefront that gets to the boundary first, slows down first. The … download 1528kb .zip Last Modified: February 12, 2020
Lenses
A wave that passes all the way through a piece of material with parallel sides leaves the material at the same angle that it entered. The wave un-bends when it exits the material by the same amount that it bent when entering but this is only true if the sides of the … download 1527kb .zip Last Modified: May 30, 2018
Dispersion
The speed of a wave can depend on the frequency of the wave, a phenomenon known as dispersion. Although this effect is often small. it is easy to observe with a prism. download 1524kb .zip Last Modified: February 16, 2018
Adding Waves
When two waves of the same type come together it is usually the case that their amplitudes add. So two overlapping water waves have an amplitude that is twice as high as the amplitude of the individual waves. This is called constructive interference and it can occur … download 1525kb .zip Last Modified: February 17, 2019
Sinusoidal Waves II
Sinusoidal waves have the property, called superposition, that their amplitudes add linearly if they arrive at the same point at the same time. This gives rise to several interesting phenomena in nature which we will investigate in this and the next few simulations. download 1529kb .zip Last Modified: March 19, 2023
Adding Sinusoidal Waves
Sinusoidal waves have the property, called superposition, that their amplitudes add linearly if they arrive at the same point at the same time. This gives rise to several interesting phenomena in nature which we will investigate in this and the next few simulations. download 1529kb .zip Last Modified: March 19, 2023
Path Difference
If two sources of waves are in phase to start with, when they reach a distant location they may be in-phase (leading to constructive interference) or out-of-phase (leading to destructive interference) depending on slight differences in the distance traveled. This … download 1517kb .zip Last Modified: February 23, 2019
Interference
This simulation shows a top view of waves interfering on the surface of a tank of water (imagine tapping the surface of a pond with the end of a stick at regular intervals). The white circles coming from the spot represents the wave crests with troughs in between. … download 1533kb .zip Last Modified: May 29, 2018
Diffraction
Sometimes waves don't travel in a straight line, even if their speed does not change (as in the case of refraction). For example, you can hear the conversation in the next room even though you cannot see the source. This is because sound waves undergo diffraction, … download 1530kb .zip Last Modified: February 20, 2019
Doppler Shift
If the wave source or receiver is moving, the waves will appear to have a different frequency. For example if you are moving towards a sound source you catch up with the next peak in the wave sooner than you would expect because you are moving towards it. This effect … download 1536kb .zip Last Modified: February 20, 2018
Pitch, Loudness and Timbre
The mechanism of human hearing does not operate as a perfect scientific instrument. In this chapter we relate a few subjective measurements of sound (things people report after hearing a sound) to objective, scientific measurements (measurements made in a laboratory … download 1859kb .zip Last Modified: February 24, 2024
Sound Texture
This simulation explores the aural texture of four basic periodic waveforms: sine, triangle, square, and sawtooth. The sine waveform has a single frequency and is the building block of other periodic waves by summing harmonics in a Fourier Series as we will see in … download 1413kb .zip Last Modified: April 16, 2023
Fourier Series
The French Mathematician Jean Baptiste Joseph Fourier showed any periodic function can be formed from an infinite sum of sines and cosines. This is very convenient because it means that everything we know about sines and cosines applies to a periodic function of any … download 1401kb .zip Last Modified: February 24, 2018
Microphone Sound Analyzer
This is an exercise using a Fast Fourier Transform to analyze sound from your computer or mobile devices microphone. download 1374kb .zip Last Modified: December 9, 2019
The Ear and Perception
We look at how the ear turns vibrations into the perception of sound. Some of the exact details of this process are still not completely understood but the general picture of how we hear is fairly well established. Once again we will see that the human hearing … download 1413kb .zip Last Modified: March 20, 2021
Beats
The phenomena of beats occurs when two notes are close together in frequencies and we perceive one note which varies in loudness. A guitar string can be tuned by comparing a note with a known pitch and tuning the string until the beats disappear. What happens if the … download 1598kb .zip Last Modified: April 19, 2023
Driven String and Resonance
In this simulation a string is driven at one end by an oscillating driver. The result is that a wave will eventually form on the string. At certain frequencies the wave will become large and we refer to this resonance phenomena as a standing wave. download 1225kb .zip Last Modified: March 20, 2021
Plucked String
In this section a set of initial conditions for a vibrating string is shown. The first is the fundamental frequency of the string, the second is the second harmonic. The third and fourth initial conditions simulate plucking in the center and at a location one fourth of the way along the string. download 1152kb .zip Last Modified: December 18, 2017
Vibrating Plates
The Vibrating Plates simulation allows you to examine vibrational modes on a rectangular surface. The surface is fixed at the edges so the nodal lines occur in different places compared to a rectangle with free edges. The model assumes that the surface is very thin … download 1249kb .zip Last Modified: March 4, 2018
Sanding Waves in a Tube
This section shows a simulation that compares the fundamental, second, third and forth harmonics of standing waves on a string with standing waves in a tube. Notice that for a tube open on both ends the displacement nodes occur where the string has nodes and the … download 1461kb .zip Last Modified: January 13, 2018
Reflection of Waves at a Boundary
Waves on a string form standing waves because the wave reflects from each end of the string where there is a fixed node. How do standing waves form in a tube full of air? This section shows that waves reflect from the end of a tube and that this reflection can be of … download 1516kb .zip Last Modified: March 16, 2018
Impedance
But why do sound waves reflect from the open end of a tube or when the size of tube changes abruptly? The resistance to the movement of a wave crossing a boundary from one medium into another is called impedance and occurs for waves on a string, sound waves in air … download 1513kb .zip Last Modified: April 2, 2021
Percussion and Drumheads
This section allows you to see and manipulate the modes for a square drum head. You can change the modes using the sliders to change the mode numbers n and m. For a membrane there are nodal lines which do not vibrate similar to the nodes we saw on the string but now … download 1178kb .zip Last Modified: March 15, 2021
The Human Voice
As we know, musical instruments consist of a vibration which is amplified by resonance. The human singing voice is no different. The vocal chords are the vibrating part and the throat, mouth, nasal cavities and bronchial tubes constitute the resonance cavities that … download 1435kb .zip Last Modified: April 16, 2023
Musical Scales
The notes on a musical instruments are organized into scales and we would like to have a scale where we get the greatest number of combinations that sound good together. We also would like to standardize the scale in such a way that if we build other instruments, two … download 5375kb .zip Last Modified: April 19, 2023
Acoustics
The study of what happens to sound in an enclosed space or as the result of interactions with large objects such as buildings is called acoustics. Humans have been trying to improve the acoustics of auditoriums and other public spaces since the time of the ancient … download 1667kb .zip Last Modified: May 1, 2023
E&M: Ohm's Law
The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor. It is measured in Ohms and the relation between resistance (R), current (I) and electrical potential (V) is Ohm's law: V = IR. … download 6454kb .zip Last Modified: January 5, 2018
E&M: Currents and Magnetic Fields
In this section we study the magnetic field of either a permanent magnet or the field produced by a flow of current in a coil. Field is measured in Gauss. The compass, magnet and coil are all draggable. The earth's magnetic field can also be demonstrated. download 6489kb .zip Last Modified: January 13, 2018
E&M: Electric and Magnetic Forces
In this section we study electric and magnetic fields with different orientations to see their effects on neutral, positive and negative charges. For the electric field case the particles have zero initial velocity. In second case with a magnetic field in the … download 6726kb .zip Last Modified: April 24, 2019
E&M: Faraday's Law
If a changing magnetic field is present near a wire that is part of a circuit it will cause current to flow in the circuit. This is known as Faraday's law and is the basis for a lot of modern technology. Electric generators, traffic detectors embedded in the road, … download 6733kb .zip Last Modified: April 21, 2018
Electronics
It is not possible to record, transmit and replay sounds perfectly so that they sound exactly as they were heard originally. This chapter explains several electronic devices used in sound recording and reproduction using concepts that were introduced in previous chapters. download 17998kb .zip Last Modified: May 1, 2023
|