#acl Narf:read,write,delete,revert,admin FacultyGroup:read,write All:read
||<25%  style="text-align:center">[[PiraScheme#WavesSound|Table of Waves and Sound]] ||<25%  style="text-align:center">[[WaveMotion|Waves and Sound(3B): Wave Motion]] ||<25%  style="text-align:center">[[Instruments|Waves and Sound(3D): Instruments]] ||<25%  style="text-align:center">[[Demonstrations|Lecture Demonstrations]] ||


== Acoustics ==
''PIRA classification 3C''

= 3C10. The Ear =
||<10%  style="text-align:center">'''PIRA #''' ||<style="text-align:center">'''Demonstration Name''' ||<style="text-align:center">'''Subsets'''||<60%  style="text-align:center">'''Abstract''' ||
||3C10.10 ||model of the ear || || ||
||3C10.20 ||time resolution of the earv || ||
||3C10.20 ||binaural hearing || ||Hold the ends of a long tube to each ear and have someone tap in the center and then a few centimeters to each side. ||
||3C10.21 ||direction judgment of the ear || ||High frequency location depends on difference in intensity produced by the shadow of the head. ||
||3C10.21 ||direction judgment of the ear || ||Location of low pitched sounds depends on phase difference. Use a model stethoscope with one tube longer than the other. ||
||3C10.30 ||bone conduction || || ||


= 3C20. Pitch =
||<10%  style="text-align:center">'''PIRA #''' ||<style="text-align:center">'''Demonstration Name''' ||<style="text-align:center">'''Subsets'''||<60%  style="text-align:center">'''Abstract''' ||
||3C20.10 ||range of hearing ||pira200||Use an oscillator driving a good audio system to demonstrate the range of hearing. ||
||3C20.10 ||range of hearing || ||A set of good speakers is used to test the student's range of hearing. ||
||3C20.10 ||range of hearing || ||An oscillator driving a good audio system is used to demonstrate the range of hearing. ||
||3C20.11 ||range of hearing || ||Use whistles, forks, etc. to establish upper range of hearing or an audio oscillator from 10 to 30,000 Hz. ||
||3C20.15 ||Galton whistle || ||The Galton whistle can be adjusted to produce an intense sound into the ultrasonic range. ||
||3C20.16 ||ultrasonic waves || ||A set of steel rods tuned to frequencies up to 30 KHz are struck with a hammer and the sound both heard and displayed on an oscilloscope. ||
||3C20.17 ||ultrasonic vibrations of quartz || ||Making an ultrasonic transducer and using it to make a fountain and emulsion. ||
||3C20.20 ||zip strips || || ||
||3C20.25 ||musical bottles || ||Blow across a set of bottles with water levels adjusted to give a scale. ||
||3C20.30 ||siren disc || ||An air jet is directed at a rotating disc with holes. ||
||3C20.30 ||siren disc || ||Air is blown through concentric rows of regularly spaced holes on a spinning disc. Change of speed of the disc changes frequencies but not intervals. ||
||3C20.30 ||siren disc || ||A disc with concentric ring of equally spaced holes is spun by a motor and a jet of air is blown at each circle of holes. ||
||3C20.40 ||frequency and pitch || ||A set of gears on a single shaft of a variable speed motor have the ratios of 44-47-49-52-55-59-62-66-70-74-78-83-88. ||
||3C20.40 ||musical saw || ||A card is held against a dull saw as the speed is varied. ||
||3C20.40 ||tooth ratio scale || ||A set of gears with 44-47-49-52-59-62-66-70-74-83-88 teeth are mounted coaxially on a shaft connected to a variable speed motor. Varying the speed shows intervals are determined by frequency ratios rather than absolute pitch. ||
||3C20.40 ||Savart wheel || ||Hold a stiff cardboard against the rim of a spinning toothed wheel. Use wheels on the same shaft each with different numbers of teeth. ||
||3C20.40 ||Savart's wheels || ||A major chord is produced when a cardboard is held against rotating wheels with tooth ratios of 3:4:5:6. ||
||3C20.40 ||gear and card || ||Hold a card against gears on a common shaft with teeth in ratio of 4:5:6:8. ||
||3C20.41 ||saw blade organ || ||Several saw blades are mounted on the same rotating shaft with sound produced by amplifying the output of a coil pickup. A band of switches selects the active blades, allowing chords to be played. ||
||3C20.45 ||pitch sort of || ||Many examples of sound of poor quality but with some definite pitch. E.g., a thumbnail on a book cover. ||
||3C20.70 ||sound cart || ||All the instrumentation for a physics of sound course is loaded on one mobile cart. ||


<<Anchor(Inensity)>>

= 3C30. Intensity and Attenuation =
||<10%  style="text-align:center">'''PIRA #''' ||<style="text-align:center">'''Demonstration Name''' ||<style="text-align:center">'''Subsets'''||<60%  style="text-align:center">'''Abstract''' ||
||3C30.20 ||dB meters and horn ||pira200||Place dB meters in the class at 2 meter intervals, then blow a loud horn. ||
||3C30.21 ||dB meter and horn || ||An air horn driven by a compressed air tank gives a 120 dB sound at close range. Use a dB meter to measure the intensity at various ranges. ||
||3C30.21 ||air horn || ||A railroad horn blown from a tank of compressed air has a nearby intensity of 110 dB. ||
||3C30.22 ||[[Sound_Level_Meter]] || ||A sound level meter is used to measure the intensity of the instructor speaking, the audience, etc. ||
||3C30.30 ||loudness (phones and sones) || || ||
||3C30.35 ||hearing -3dB || ||A function generator with a dB meter is used to quickly adjust to half power. ||
||3C30.36 ||3 dB || ||One and two students pound the table equidistant from an observer. ||
||3C30.41 ||attenuation of materials || ||place various materials between a sounding board and a tuning fork stuck in a block of wood. ||
||3C30.42 ||modified tuning fork resonance box || ||The tuning fork is removed from a resonance box and a rod, string, and water are interposed. ||
||3C30.43 ||attenuation in CO2 || ||A high pitched tone transmitted through a 10' pipe will be attenuated when filled with CO2. ||
||3C30.45 ||acoustical tiles || ||Show various acoustical tiles. ||


= 3C40. Architectural Acoustics =
||<10%  style="text-align:center">'''PIRA #''' ||<style="text-align:center">'''Demonstration Name''' ||<style="text-align:center">'''Subsets'''||<60%  style="text-align:center">'''Abstract''' ||
||3C40.10 ||room reverberation time || ||Go around and record pistol shots in various rooms, then determine reverberation time at different frequencies with some equipment in the classroom. ||
||3C40.10 ||reverberation time || ||Students clap hands to generate sound for reverberation time. ||
||3C40.10 ||reverberation time || ||Study the reverberation time of a room. ||
||3C40.10 ||reverberation time || ||Measure reverberation time of the classroom with a dB meter. (-60dB) ||
||3C40.11 ||reverberation tube || ||Measure the time required for sound to die in a tube that can be fitted with caps of various materials. ||
||3C40.20 ||ripple tank acoustics || ||Cross sectional models of various auditoriums are used in a ripple tank to show scattering and reflection. ||


= 3C50. Wave Analysis and Synthesis =
||<10%  style="text-align:center">'''PIRA #''' ||<style="text-align:center">'''Demonstration Name''' ||<style="text-align:center">'''Subsets'''||<60%  style="text-align:center">'''Abstract''' ||
||3C50.10 ||Pasco Fourier synthesizer || ||The Pasco Fourier synthesizer allows one to build an arbitrary waveform with up to nine harmonics. ||
||3C50.10 ||Pasco Fourier synthesizer || ||The Pasco Fourier synthesizer is used to build up a square wave. ||
||3C50.10 ||Pasco Fourier synthesizer || ||The Pasco Fourier synthesizer allows one to build an arbitrary waveform out of up to nine harmonics. ||
||3C50.10 ||Fourier synthesizer || ||Use the Pasco Fourier synthesizer to demonstrate building square and triangle waves. ||
||3C50.12 ||electronic music synthesizer || ||The principles of an electronic music synthesizer and its use in demonstrations. ||
||3C50.12 ||electric organ as synthesizer || ||The timbre of a musical note is demonstrated by showing an oscilloscope trace of an electric organ while changing the drawbars. ||
||3C50.13 ||electromechanical Fourier synthesize || ||A set of eight mechanically geared potentiometers generate sine/cosine waves and harmonics. ||
||3C50.13 ||mechanical multichannel generator || ||A four channel mechanical signal generator is used to show a fundamental and two harmonics. Picture. Construction details in appendix, p. 626. ||
||3C50.14 ||synthesizer || ||The PAiA 2720 Synthesizer used with an oscilloscope for ten demonstrations. ||
||3C50.14 ||waveform synthesizer || ||Oscillators tuned to 1, 2, 3, 4, and 5 Khz have variable amplitude and phase. External input and an audio amp are also included. ||
||3C50.14 ||waveform synthesizer || ||A waveform synthesizer based on the Intel 8748 microcontroller is described along with some theory and an experiment. ||
||3C50.15 ||mechanical square wave generator || ||Shadow project a mechanism with a small disc mounted at the edge of a larger disc with 1/3 the diameter geared to rotate 3 times as fast as the larger disc. ||
||3C50.18 ||arbitrary waveform generator || ||Sweep a high freq signal at a low freq on an oscilloscope with a mask cut out to the shape of the wave desired and look at it with a photocell. ||
||3C50.30 ||Helmholtz resonators and microphone || ||Hold a small microphone individually to a set of Helmholtz resonators. ||
||3C50.31 ||Helmholtz resonator || ||Sound from a loudspeaker is directed at a series of Helmholtz resonators with pinwheel detectors at their small apertures. ||
||3C50.31 ||ganged resonance boxes || ||A pistol is fired in front of a set of tuning fork resonance boxes equipped with inductive pickups. Picture. ||
||3C50.33 ||resonance in a box || ||A complex setup to plot the frequency spectrum of a box. Pictures, Diagrams. ||
||3C50.34 ||resonant response of vocal cavities || ||Use a fake larynx to talk without using the vocal cords. ||
||3C50.35 ||resonance tube spectrum || ||Drive a speaker at one end of a tube with the swept frequency output of a spectrum analyzer. ||
||3C50.36 ||air column resonance spectra || ||Use a storage scope and two function generators to display the swept spectrum. Interesting additions are end corrections, tone holes, and adding a bell. ||
||3C50.37 ||radiation patterns of horns || ||Feed a oscillator or other sound to any one of four different types of horns to show differences in quality at various frequencies. ||
||3C50.40 ||harmonic tones (vibrating string) || || ||
||3C50.40 ||string resonance spectra on oscillo. || ||Sweep the source generator and oscilloscope horizontal from a generator. Use a steel wire and guitar pickup. ||
||3C50.40 ||resonances in strings || ||Excite a steel string with a linearly swept sinusoidal signal and show the output on a spectrum analyzer or storage oscilloscope. ||
||3C50.50 ||noise (pink and white) || || ||
||3C50.55 ||distinguishing harmonics || ||A generator with an adjustable high Q bandpass filter allows one to train the ear to pick out the harmonics of a complex sound. ||
||3C50.55 ||distinguishing harmonics || ||The circuit diagram for the Gronseth device. ||
||3C50.70 ||wave analysis (PASCO filter) || || ||
||3C50.80 ||spectrum analyzer || || ||
||3C50.81 ||RLC bank harmonic analyzer || ||A bank of RLC circuits covering to the tenth harmonic of 235 Hz is used as a harmonic analyzer. Diagram. ||
||3C50.82 ||LC harmonic analyzer || ||Sweep a square wave generator through a single LC filter and detect maximum at harmonics of the fundamental. ||
||3C50.83 ||low cost spectrum analyzer || ||A circuit for a 100 kHz spectrum analyzer using a standard oscilloscope for display. ||
||3C50.83 ||spectrum analyzer - Tek 5L4N || ||The Tek 5L4N spectrum analyzer plug-in is used with a camera (instead of a storage scope) to show the spectrum of sustained tones from musical instruments at different pitch and loudness. ||
||3C50.94 ||FFT on 6502 || ||A FFT algorithm relocatable to any 6502 is available from the author. ||
||3C50.94 ||microcomputer based analyzer || ||Discusses algorithms for cross correlation and sound intensity analysis. ||


= 3C55. Music Perception and the Voice =
||<10%  style="text-align:center">'''PIRA #''' ||<style="text-align:center">'''Demonstration Name''' ||<style="text-align:center">'''Subsets'''||<60%  style="text-align:center">'''Abstract''' ||
||3C55.20 ||pitch of complex tones || ||Use an Apple computer to generate complex tones. Students judge the pitch. ||
||3C55.25 ||missing fundamental || ||Microcomputers with built-in tone generators are handy for generating "missing fundamental" demonstrations. ||
||3C55.26 ||sing/whistle - which octave || ||Whistle and sing into a three foot pipe and use the resonances to show your whistling range is much higher than your singing range. ||
||3C55.30 ||difference tones || || ||
||3C55.30 ||subjective tones || ||A toy whistle emits tones at 2081, 1896, and 1727 Hz. Subjective difference tones at 169, 185, and 374 Hz are clearly audible. ||
||3C55.31 ||combination tones and the ear || ||Explanation of how the nonlinear ear creates difference tones and common examples of the phenomena. Two demonstrations: sweep with a second oscillator to find the difference tone, add 200, 300 and 400 Hz to hear 100 Hz. ||
||3C55.35 ||difference tones and beats || ||Two pure tones produce beats or difference tones. Theory and a demonstration that trains our ears to hear and distinguish the two. ||
||3C55.35 ||beats on scope, difference tones || ||The usual two oscillators, amplifier, and scope. For difference tones, set one oscillator above the audible range and the difference tone is the only thing the student can hear. ||
||3C55.35 ||beats on scope, difference tones || ||Two audio oscillators drive two speakers. A microphone pickup displays the sum on an oscilloscope. ALSO - difference tone. ||
||3C55.40 ||chords || ||Using the three string sonometer to study the structure of chords by varying the bridge location of strings tuned in unison. ||
||3C55.41 ||circular glockenspiel || ||Mallets can be put in any of twelve holes on a spool to play major, minor, augmented, and diminished cords on a circular glockenspiel. ||
||3C55.42 ||consonant musical intervals || ||Consonant and dissonant intervals are explained by a relation between the time required to perceive a definite pitch and the period of a complex tone. ||
||3C55.45 ||consonance and dissonance || || ||
||3C55.45 ||harmonious notes || ||Using the sonometer to demonstrate the harmonic content of different interval combinations. ||
||3C55.50 ||musical scale || || ||
||3C55.51 ||numerical investigation of scales || ||An investigation of why the 12 note scale is the best equal tempered scale. ||
||3C55.51 ||quantitative investigation of scales || ||A quantitative measurement of how well any tuning succeeds in providing just intonation for any specific piece of music. ||
||3C55.51 ||scales and algebraic groups || ||On transposing. ||
||3C55.52 ||lucky equal temperaments || ||An analysis of how good the fits of 12, 19, 31, and 53 steps per octave are in equally tempered scales. ||
||3C55.55 ||piano tuning || ||On making use of instrumentation to help with piano tuning. ||
||3C55.55 ||piano tuning || ||A pianist discusses the finer points of piano tuning. ||
||3C55.55 ||piano tuning || ||On "stretching" the equally tempered scale. ||
||3C55.55 ||tuning forks with resonators || ||A set of tuning forks mounted on resonance boxes make the musical scale. ||
||3C55.55 ||tuning fork resonance boxes || ||A set of four different tuning forks on resonant boxes. ||
||3C55.55 ||tuning forks on resonant boxes || ||Two tuning forks, two boxes. Show the box needs to be matched to the fork. ||
||3C55.60 ||Johnson intonation trainer || ||A small organ that is switched between fixed and variable tuning to demonstrate even tempered and just intonation. ||
||3C55.65 ||tone quality || ||A series of organ pipes tuned carefully to give the harmonics of a fundamental can be used to show the effect of suppressing various harmonics. ||
||3C55.70 ||microphone and oscilloscope || ||Show the output of a microphone on an oscilloscope. ||
||3C55.71 ||sound wave on oscilloscope || ||Show a sound wave on the oscilloscope while listening to it. ||
||3C55.72 ||tone quality || ||Using a microphone and oscilloscope, demonstrate that a tuning fork does not produce a pure sine wave but a fork on a resonance box does. ||
||3C55.73 ||tone quality of a Boehm flute || ||Harmonic analysis of rich and dull tones from the Boehm flute. ||
||3C55.74 ||keyboard and oscilloscope || || ||
||3C55.75 ||forms of sounds || ||A variant of the circuit produces roulette figures, etc. ||
||3C55.75 ||voice display - corridor demo || ||A circuit to advance the horizontal 45 degrees and retard the vertical 45 degrees to give a circular trace when a falsetto "o-o-o" is sung. ||
||3C55.80 ||formants || ||Sing formants into a HP analog spectrum analyzer. ||
||3C55.80 ||vocal formants || ||Use an computer based real time spectrum analyzer to display vocal formants. ||
||3C55.82 ||tone quality || ||Using a phonelescope or oscilloscope, sing the different vowels at the same pitch and the same vowels at different pitches. ||
||3C55.85 ||filtered music and speech || || ||
||3C55.85 ||octave-band filters || ||Use an octave-band filter (from an audio store) to demonstrate filtered music and speech. ||
||3C55.90 ||Book/CD review - piano acoustics || ||Review of a book "Acoustics of the Piano" that comes with a CD that includes examples used in the lectures. ||
||3C55.90 ||musical sound records || ||The Science of Sound - Bell Labs, Energy and Motion - Zaret and Singer, Experimental Songs - Dorothy Collins, Space Songs - Tom Glazer & Dottie Evans, Physics Songs - State University of Iowa. ||
||3C55.99 ||churchbell guitar || ||Swing a guitar back and forth as it is plucked to mimic a church bell. ||


[[Demonstrations]]

[[Instructional|Home]]