Table of Waves and Sound

Waves and Sound(3C): Acoustics

Waves and Sound(3E): Sound Reproduction

Lecture Demonstrations

Instruments

PIRA classification 3D

3D20. Resonance in Strings

PIRA #

Demonstration Name

Abstract

3D20.10

sonometer

A sounding box with strings, tuning machines, and adjustable bridges.

3D20.10

sonometer

A long spruce box with three strings, tuning machines, and adjustable bridges.

3D20.11

vertical sonometer

A vertical sonometer allows tension to be applied by simply hanging weights.

3D20.14

tuning fork driven sonometer

Place a tuning fork on the bridge of a tuned sonometer and observe the motion of a small piece of paper placed on the wire at its center.

3D20.15

harmonics on a string

Pluck a string at different distances from the end or pluck while touching at various nodes.

3D20.20

modes of string oscillation on scope

3D20.20

modes of string oscillation

Use voltages generated by magnets placed across steel strings attached to an oscilloscope to view string motion.

3D20.20

sonometer

An electromagnetic pickup is used to display the waveform of the sonometer string on an oscilloscope.

3D20.21

guitar and scope

Show the output of an electric guitar on an oscilloscope.

3D20.30

bowed string

An overhead projector is modified for strobe projection and the string is bowed with a motorized "O" ring.

3D20.30

sonometer wire motion

Demonstrate the motion of a sonometer wire by stroboscopic shadow projection or using a light beam and revolving mirror.

3D20.30

string in a projector

The motion of a string is shown by placing any portion in a lantern projector limited by a slit. The difference in bowing, plucking, and striking can be demonstrated.

3D20.31

optical detection of string motion

An optical detection system for showing the position of a vibrating string.

3D20.35

resonance of strings

A tuning fork is held against a three string sonometer with one string tuned to the fork frequency. Only the tuned string will vibrate.

3D20.36

simulated piano string coupling

A classroom device that simulates the coupled motion of piano strings and theory of the device.

3D20.45

longitudinal vibrations in strings

Stroke a string attached to a diaphragm across the open end of a cylinder. By jerking, you can make it bark like a dog.

3D20.52

aeolian harp

Mount strings vertically on a rotating table to give the sound of strings excited by the wind.

3D20.52

aeolian scope

A sort of aeolian stethoscope.

3D20.60

rubber-band harp

The pitch of a rubber-band changes only slightly with great increase in length (tension).

3D22. Stringed Instruments

PIRA #

Demonstration Name

Abstract

3D22.10

violin

3D22.20

cigar box cello

A wooden cigar box serves as sounding box for a one string violin.

3D22.20

cigar box cello

A one string violin made with a cigar box body.

3D30. Resonance Cavities

PIRA #

Demonstration Name

Abstract

3D30.10

vertical resonance tube

Draw a glass tube out of a water bath while holding a tuning fork over one end.

3D30.10

veritcal resonance tube

The length of a glass tube is varied by pulling it out of a water reservoir. A tuning fork is used as a frequency source.

3D30.10

vertical resonance tube modification

Design of a clamp to hold the tuning fork and resonance tube, and a bracket for the water reservoir.

3D30.10

vertical resonance tube

A glass tube is drawn out of a water bath while holding a tuning fork over one end.

3D30.10

vertical resonance tube

Use a tuning fork to excite the air column in a vertical tube as it is pulled out of a water bath.

3D30.11

vertical resonance tube

Blow across the mouth of bottles or a adjustable air column.

3D30.12

vertical resonance tube

A vertical tube is mounted over a siren disk.

3D30.14

open tube resonance

A length of open tube adjusted by a paper extension and excited by a tuning fork.

3D30.15

resonance tube with piston

Mount a microphone on a piston that slides in a glass tube and close the other end of the tube with a speaker.

3D30.16

horizontal resonance tube

A plunger on a rod is used to change the effective length of a horizontal glass tube as a tuning fork supplies the exciting frequency.

3D30.16

organ pipe velocity nodes

Lower a ring with a membrane and sand into a pipe with a clear side to observe velocity nodes and antinodes.

3D30.17

modes of a bottle

A thorough discussion of modes of various bottles working up to a 3-D model.

3D30.19

low frequency generator

A special tip for an air jet that produces many frequencies of low intensity useful for exciting enclosed air columns.

3D30.20

open and closed tubes 256/512

3D30.20

resonance tube 256/512

A tube is cut to length to resonate at 256 Hz when closed and 512 Hz when open.

3D30.21

conical pipes

Corrections for the effective length of open and closed circular pipes are given. A conical pipe discussion with several interesting demonstrations is listed.

3D30.35

Corrugaphone

3D30.35

Hummer tube

The complete explanation on singing corrugated pipes.

3D30.35

freq tube dash pot

A freq tube is attached to coffee can moved up and down in a pail of water.

3D30.35

freq tube

Open tubes of corrugated plastic are whirled around.

3D30.40

Helmholtz resonators

A set of spherical resonators made of spun brass.

3D30.40

Helmholtz resonators

A small vane is rotated when placed near the small opening of a resonating Helmholtz cavity.

3D30.40

acoustic resonator

This picture appears to be of a Helmholtz resonator.

3D30.40

Helmholtz resonators

Two resonators are matched to two tuning forks.

3D30.41

tuning a resonance box

The hole size of a resonance box is adjusted to maximize resonance with a tuning fork.

3D30.43

Fizeau resonance box

A toothed wheel is used to produce a high pitched sound and an adjustable resonance box with a sensitive flame detector is used to determine speed of sound.

3D30.45

ploop tubes

Stoppers are removed from a set of tubes of varying length.

3D30.45

ploop tubes

Pull stoppers out of test tubes filled with water to different depths.

3D30.50

Ruben's tube

The standard Reuben's tube.

3D30.50

Ruben's tube

A gas filled tube with flames from a row of holes along the top and a speaker at one end.

3D30.50

Ruben's tube

Directions for building a Ruben's tube. Picture, Diagrams.

3D30.50

Ruben's tube

Drill a line of holes along a downspout and drive one end with a loudspeaker and introduce gas in the other. Flames indicate nodes and antinodes.

3D30.50

Ruben's tube

A horn driver is used as a sound source.

3D30.55

Rubens tube comment

A comment on AJP 53,1110 (1985).

3D30.55

Rubens tube flame structure

An examination of the structure of the flames in the normal mode (flame maxima at pressure nodes).

3D30.55

Ruben's tube nodes

The pressure is measured at each flame hole and the results are that the flames are larger at the pressure antinodes.

3D30.55

Ruben's tube nodes

A comment on a note that the tube can be operated with flame maxima at either pressure node or pressure antinode.

3D30.60

Kundt's Tube

Sawdust in a tube makes piles when driven by rubbing a rod attached to a disc.

3D30.60

Kundt's tube

Standard Kundt's tube: glass tube with cork dust, stroke a rod to excite air in tube.

3D30.60

Kundt's tube

Stroke a rod to excite cork dust in a tube.

3D30.61

horn driven Kundt tube

Investigation of striations in an electrically driven Kundt tube.

3D30.61

Kundt's tube

The cork dust in Kundt's tube is excited by a horn driver.

3D30.62

Kundt's tube

A variation of Kundt's tube with an organ pipe made with one side of rubber or cellophane and sprinkled with sand while laid on its side.

3D30.63

Kundt's tube on the overhead

A Kundt's tube is modified for use on the overhead projector.

3D30.64

evacuate Kundt's tube

Show the effect of pressure variation on the speed of sound by partially evacuating the Kundt's tube.

3D30.65

hot wire Kundt's tube

Cooling of a glowing wire down the center of a tube indicates standing waves.

3D30.65

horizontal resonance tube - wire

A nichrome wire stretched down the middle of a glass tube and heated electrically will glow to show standing waves.

3D30.65

hot wire pipe

Blow a whistle at one end of a tube with a hot wire running down the axis to show areas of low and high luminosity.

3D30.66

Kundt's tube - impedance measurement

Use the oscilloscope to show variation of impedance in the driving coil with changes in tube length.

3D30.69

pressure distribution in a cavity

Liquid deformation on the bottom of an acoustic cavity shows the time-dependent pressure distribution in a standing sound wave.

3D30.70

hoot tubes

A Bunsen burner heats a screen in the bottom of a large open vertical tube.

3D30.70

hoot tubes

Large glass tubes sound when a wire mesh at one end is heated with a Bunsen burner.

3D30.70

hoot tubes

A Bunsen burner heats a screen in the bottom of a large open tube.

3D30.70

hoot tubes

Singing tubes excited by hot gauze.

3D30.70

hoot tubes

Hints for making a singing tube work with only flame excitation.

3D30.70

singing pipes

Two metal tubes and a glass one.

3D30.71

hoot tube

Insert a fisher burner in a tube.

3D30.72

hoot tubes

The gauze in a hoot tube is held at the bottom of the tube and the flame is lit above it.

3D30.73

Rijke Tube - electrical heating

Construction of electrically heated Rijke tubes, tuning a T shaped tube.

3D30.74

variable hoot tubes

3D30.75

Knipp tubes

Knipp tubes are a special form of singing tube made by holding a short length of glass tube in the closed end of a larger tube. Picture. Ref. F.R.Watson, "Sound"p.214.

3D30.77

hot chocolate effect

Tap on a tall cylinder full of water and then repeat with hot water so there are lots of bubbles. The pitch descends three octaves and rises as the bubbles float up.

3D30.77

hot chocolate effect - comment

A few explanations from a physical chemist.

3D30.77

hot chocolate effect

Tap on the bottom of an empty glass, a full glass (higher pitch), and a glass full of tiny bubbles (pitch raises as glass clears. Methods of generating bubbles with beer and hot water. More.

3D32. Air Column Instruments

PIRA #

Demonstration Name

Abstract

3D32.10

tin flute

Open and close holes on a tin flute to find pressure nodes and antinodes.

3D32.10

organ pipes with holes

Show open and closed pipes of various lengths and one with holes bored in the side to give the diatonic scale.

3D32.10

resonance tubes (three lengths)

Blow air out of a flat nozzle across a set of three different length tubes.

3D32.13

shrieker

Insert a 1/2" dia. tube 12" long into a bottle of water and blow across.

3D32.15

slide whistle

Use a high quality sliding whistle made for band.

3D32.15

variable pitch whistle

A whistle with a sliding piston.

3D32.15

slide whistle

The variable length organ pipe.

3D32.16

bird call

Directions for making a bird call. Diagram.

3D32.20

organ pipes with holes

3D32.24

Organ_Pipes

A collection of open, closed, and variable length organ pipes.

3D32.25

Open and Closed End Organ Pipes

Three organ pipes, open and closed.

3D32.27

"C" bazooka

A 1.314 m brass tube sounds the note "C" when blown with the lips.

3D32.30

slide whistle

3D32.35

demonstration trumpet

Interchangeable mouthpiece, leadpipe, cylindrical section, and bell allow one to show the function of the various parts of the brass instruments.

3D32.36

hose in the bell

With a garden hose in the bell of a trombone (flush with the end), the tones are: 3:5:7:9:11 and without the hose: 2:3:4:5:6.

3D32.40

demonstration trumpet

3D32.40

PVC instruments, etc.

Very good instructions on making various instruments out of PVC. Also using a computer with a synthesizer to study scales.

3D40. Resonance in Plates, Bars, Solids

PIRA #

Demonstration Name

Abstract

3D40.10

glockenspiel

A small xylophone can be played to demonstrate the musical scale.

3D40.10

xylophone

A small xylophone.

3D40.10

xylophone bars

Use a microphone and oscilloscope to display the waveforms of various notes on a xylophone.

3D40.11

rectangular bar oscillations

Strike a three foot rectangular bar on different faces and on the end. Listen to the different frequencies.

3D40.12

high frequency metal bars

Hold a metal rod at the midpoint and strike at the end. Two rods an octave apart are shown.

3D40.15

musical sticks

A set of wood sticks play a major scale when dropped on the lecture table.

3D40.15

musical sticks

A set of wood sticks is cut so they sound the musical scale when dropped.

3D40.15

musical sticks

Directions for making musical sticks.

3D40.15

musical sticks

A set of sticks give a complete scale when dropped.

3D40.16

musical nails

3D40.20

singing rod

Hold a long aluminum rod at the midpoint and stroke with rosened fingers.

3D40.20

singing rod

A long aluminum rod will sing when held at the center and stroked with a rosin coated leather.

3D40.20

singing rods

Hold a long aluminum rod at the midpoint and stroke with rosined fingers.

3D40.21

singing rod

Stroke a 1/2" x 72" aluminum rod while holding at nodes to produce different harmonics.

3D40.23

bow the vertical rod

A long thin rod attached to a short thick rod clamped vertically is bowed and plucked while held at various positions.

3D40.24

regenerative feedback in rod

A detector at one end, speaker at the other, and an amplifier in between provides a regenerative feedback system for exciting a rod in the fundamental frequency.

3D40.24

speed of sound in a rod

Stroke a loud rod to get a squeal, tune a oscillator and speaker to get rid of beats, and calculate the velocity.

3D40.24

speed of sound in a metal wire

Wire is stretched tightly and stroked with a wet sponge.

3D40.24

velocity of sound in a rod

A rod clamped in the middle is excited by a coil at one end tuned until a Lissajous pattern is formed on an oscilloscope with the signal from a microphone placed at the other end.

3D40.24

singing rod

A rod is excited electromagnetically at one end and the motion is detected in the same manner at the other end for quantitative studies.

3D40.27

singing rod

Find Young's modulus by finding the sag in a rod and then compare the frequency of the fundamental mode with theory.

3D40.30

Chladni plate

Strike or bow a horizontal metal plate covered with sand while touching the edge at various nodal points.

3D40.30

Chladni plate

A brass plate clamped horizontally in the center is bowed while the edges are touched to provide user selected nodes. Banding sand shows patterns of oscillations.

3D40.30

Chladni plates

Bow the Chladni plate while damping at node locations with a finger.

3D40.30

Chladni plates

Excite the Chladni plates with a cello bow. Picture.

3D40.30

Chladni plate

A horizontal metal plate covered with sand is struck or bowed while touching the edge at various nodal points.

3D40.30

Chladni plates

Bow circular and square Chladni plates.

3D40.30

Chladni plates

A plate is driven by magnetostriction in the 10 to 30 Khz range.

3D40.31

Chladni plates

Sprinkled sand shows standing waves on a circular metal plate driven at the center by an oscillator.

3D40.31

Chladni plates

Drive a Chladni plate from the center.

3D40.32

Chladni Plate: Violin

Directions for making a loudspeaker driven Chladni plate for the overhead projector.

3D40.32

Chladni plates

Chladni plates are driven from above by a loudspeaker. Pictures.

3D40.33

thick Chladni plate

A circular disc of 1/2" aluminum exhibits a single pattern.

3D40.34

Chladni plates

After some interesting historical and general comments, nonflat plates (cymbals, gongs, etc.) are examined.

3D40.35

2-D flame table

Two-dimensional rectangular and circular flame tables, extensions of the one-dimensional Rubens tube, are shown in some lower order modes

3D40.35

flaming birthday cake

Flames from a two dimensional array driven by a speaker show many resonant modes.

3D40.36

2D flame table analysis

An analysis of the two dimensional flame table.

3D40.40

Chladni figures - tympani head

Drive a timpani head with a loudspeaker.

3D40.40

standing waves on a drum

A speaker drives a circular rubber membrane under tension while illuminated with a strobe.

3D40.40

standing waves in a drum

A circular rubber membrane with a pattern is illuminated with a strobe and driven from below by a 12" loudspeaker. Pictures.

3D40.40

drumhead

A speaker drives a drumhead.

3D40.41

vibrations in a circular membrane

The eigenfrequencies of (21) agree closely with the theoretical values. Air damping is removed by using a wire mesh driven magnetically.

3D40.45

bubble membrane modes

Use a large right angle PVC fitting.

3D40.45

soap film membrane modes

Light from a slide projector is reflected off a soap film with a black cloth and speaker behind.

3D40.45

bubble membrane modes

A simple technique to drive bubble membranes of various shapes with a speaker.

3D40.50

musical goblets

Rub the edge of a goblet with a wet finger.

3D40.50

glass tumbler

Rub a finger dipped in vinegar around the top of a crystal goblet.

3D40.51

standing waves in a bowl

A 15 l flask is cut in half to form a bowl which is bowed to produce standing waves. Suspended ping pong balls indicate nodes and loops.

3D40.51

bowing the bowl

Suspend four pith balls so they touch the edge of a bowl and bow between two of the balls.

3D40.52

"whispering" waves in a wineglass

A thorough discussion of surface waves in vessels, including ethylene glycol in a trifle dish.

3D40.52

wineglass acoustics

A study of wineglass acoustics.

3D40.53

wine glass waves, etc.

Seven questions about wine glass waves are answered. Pictures of a glass harmonica and a Chinese "water spouting basin".

3D40.55

Breaking Glass with Sound

A large 2" horn driver is used with an audio amplifier is used to break glassware/Stemware at it's resonant frequency by the use of an adjustable function generator to deliver a pure tone. Strobe light can be added to show the oscillations of the glass before it shatters.

3D40.60

wind chimes

Directions for making wind chimes. Some discussion of the perception of complex tones.

3D40.60

aeolian "bull roarer"

The Australian "bull-roarer" produces a loud noise due to eddies in the air.

3D40.65

bull roarer

3D40.90

spherical oscillations movie

A description by the author of a computer generated movie of spherical oscillations.

3D42. Percussion Instruments

PIRA #

Demonstration Name

Abstract

3D46. Tuning Forks

PIRA #

Demonstration Name

Abstract

3D46.15

Tuning_Fork_Sets

Various sets of tuning forks are shown.

3D46.16

Tuning_Fork_Waveforms

Use a microphone and an oscilloscope to display the waveforms of tuning forks of varying frequencies.

3D46.20

Tuning Forks

Strike two tuning forks. Hold one against the table and the other in the air. When the first is no longer audible, hold the second on the table.

3D46.21

tuning forks

Compare losses of tuning forks of steel and alloy, on and off a resonator box.

3D46.22

adjustable tuning fork

Adjust masses on each tine of a large fork and show the waveform on an oscilloscope. Mistuned forks damp quickly.

3D46.25

modulation of sound waves

Two tuning forks of slightly different frequencies mounted on resonant boxes couple when the amplitude is varied by an oscillating barrier between them.

3D46.30

low frequency tuning fork

Tuning fork motion can be studied with a large fork.

3D46.31

project a tuning fork

Stroboscopically shadow project a vibrating tuning fork on a screen.

3D46.40

vowel tuning forks

A set of tuning forks made to give sounds that sound like the vowels.

3D46.45

quadrupole nature of a tuning fork

Hold a tuning fork close to the ear and rotate it.

3D46.90

frequency standard tuning forks

Driven precision tuning forks of 400 and 100 Hz are used as secondary frequency standards.

3D46.90

Electronically driven tuning fork

A tube circuit for driving a tuning fork.

3D46.90

electrically driven fork

A vacuum tube circuit for driving tuning forks.

3D50. Electronic Instruments

PIRA #

Demonstration Name

Abstract

3D50.10

keyboards

Demonstrations

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