Thomas Young the Man Who Knew Everything

Total Page:16

File Type:pdf, Size:1020Kb

Thomas Young the Man Who Knew Everything Thomas Young The man Who Knew Everything Andrew Robinson marvels at the brain power and breadth of knowledge of the 18th-century polymath Thomas Young. He examines his relationship with his contemporaries, particularly with the French Egyptologist Champollion, and how he has been viewed subsequently by historians. ORTUNATE NEWTON, happy professor of natural philosophy at childhood of science!’ Albert the newly founded Royal Institution, F Einstein wrote in 1931 in his where in 1802-03 he delivered what foreword to the fourth edition of is generally regarded as the most far- Newton’s influential treatise Opticks, reaching series of lectures ever given originally published in 1704. by a scientist; a physician at a major London hospital, St George’s, for a Nature to him was an open book, quarter of a century; the secretary of whose letters he could read without the Admiralty’s Board of Longitude effort. ... Reflection, refraction, the and superintendent of its vital Nauti- formation of images by lenses, the cal Almanac from 1818 until his mode of operation of the eye, the death; and ‘inspector of calculations’ spectral decomposition and recom- for a leading life insurance company position of the different kinds of in the 1820s. In 1794, he was elected light, the invention of the reflecting a fellow of the Royal Society at the telescope, the first foundations of age of barely twenty-one, became its colour theory, the elementary theory foreign secretary at the age of thirty, of the rainbow pass by us in and turned down its presidency in procession, and finally come his his fifties. No wonder, the organizers observations of the colours of thin of an exhibition at London’s Science films as the origin of the next great Thomas Young, painted by Sir Thomas Museum in 1973 stated: theoretical advance, which had to Lawrence in the 1820s. await, over a hundred years, the Young probably had a wider range of coming of Thomas Young. some phonetic elements, an ‘alpha- creative learning than any other bet’, for spelling non-Egyptian Englishman in history. He made Everyone who studies physics at names like Ptolemy and Cleopatra. discoveries in nearly every field he school is taught that Thomas Young Less well known is that Young was a studied. (1773-1829) was the English scientist physiologist who was the first to who first demonstrated – with a explain how the human eye focuses Born to a Quaker family in Somer- candle, a pair of narrow slits and a on objects at varying distances; who set, Young was a child prodigy, who white screen – that light was a wave, discovered the phenomenon of astig- later trained as a physician in Lon- thus disproving Newton’s conviction matism; and who in 1801 proposed don, Edinburgh and Göttingen and that it consisted of a stream of par- the three-colour theory of vision, at Cambridge, where he was known ticles. Equally, anyone who studies finally confirmed experimentally in to the students as ‘Phenomenon’ ancient Egypt will know that Young 1959. Young with a mixture of respect and was the linguist and antiquarian who In addition, Young was a major derision. He has never lacked for ‘cracked’ the two Egyptian scripts on scholar of ancient Greek; a phen- admirers among great scientists. Just the Rosetta Stone, which then omenal linguist who, after compar- after Young’s death, the astronomer launched the full decipherment of ing the vocabulary and grammar of Sir John Herschel called him a ‘truly the Egyptian hieroglyphs by Jean- some 400 languages, in 1813 intro- original genius’ and added that ‘to François Champollion in the 1820s. duced the term Indo-European to do anything approaching to justice Young was the first to show that describe the language family that to his reputation … would call for demotic to some extent resembled includes Greek, Latin and Sanskrit; the exercise of powers more nearly hieroglyphic visually, hence demotic and an extraordinarily prolific and allied to his own than I can pretend was derived from hieroglyphic, and authoritative writer, mainly for the to boast’. Later in the century, the demotic was not an alphabet like the Encyclopaedia Britannica, on all man- physicist and physiologist Hermann Greek alphabet on the Rosetta Stone ner of other subjects from carpentry von Helmholtz stated that Young but rather a mixture of phonetic and music to life insurance and signs and hieroglyphic signs. This ocean tides, as well as biographies of ... was one of the most acute men who thinking led Young to suggest that eminent scientists and scholars. His ever lived, but had the misfortune to hieroglyphic, too, might contain professional appointments included: be too far in advance of his contem- APRIL 2006 HISTORY TODAY 53 THOMAS YOUNG: THE MAN WHO KNEW EVERYTHING bered today for being the first per- This applies very well to Young in son to identify clearly the similarities respect of his research on ancient between Sanskrit, Greek, Latin, Egypt – which is probably the part of Gothic (Germanic), Celtic and Old his work of greatest interest to most Persian (the language family which historians. Young’s ability to deci- Young then dubbed ‘Indo-Euro- pher the Rosetta Stone and ancient pean’) – but Jones worked in many Egyptian papyruses was undoubtedly other fields too. An Oxford Universi- fed by his powers of mathematical ty symposium on the bicentenary of analysis and scientific intuition, by his death in 1994, edited by Murray, his philological scholarship in required separate contributions ancient Greek and Oriental lan- from a Sanskritist and an Arabist, a guages, by his immersion since child- theologian, a lawyer (Jones was a hood in the civilizations of the classi- judge) and an anthropologist, cal world, and by his exceptionally among others. Murray acutely detailed knowledge of the history of remarked: ideas in science and medicine, evi- dent in all his publications, especially History is unkind to polymaths. No his greatest work, A Course of Lectures biographer will readily tackle a sub- in Natural Philosophy and the Mechani- ject whose range of skills far exceeds cal Arts, derived from his Royal Insti- Young’s work of 1815 on consumption, his own, while the rest of us, with or tution lectures and published in in which he drew on his experience of 1807, the second volume of which contracting the disease as a teenager. consists of a systematized and anno- tated catalogue containing 20,000 articles ranging from the ancient poraries. They looked on him with Greeks up to 1805. Yet, having said astonishment, but could not follow all this, Young’s contribution to the his bold speculations, and thus a mass hieroglyphic decipherment is fre- of his important thoughts remained quently underplayed and sometimes buried and forgotten in the Trans- even virtually dismissed in favour of actions of the Royal Society until a Champollion’s. Indeed, the dispute later generation by slow degrees between them has become the most arrived at the rediscovery of his notorious in the history of archaeo- discoveries, and came to appreciate logical decipherment, still partly the force of his arguments and the unresolved to this day. accuracy of his conclusions. Young stated that Champollion Diagram of the eye, from A Course of had built his system of reading hiero- While in 1899, lecturing on the Lectures on Natural Philosophy (1807). glyphics on Young’s own discoveries centenary of the Royal Institution, and his hieroglyphic ‘alphabet’, the physicist Lord Rayleigh declared published in various articles and in a simply: ‘it was seldom that [Young] without biographies to read, have no was wrong’. A century later, in 2005, mental ‘slot’ in which to keep a poly- a Nobel laureate in physics, Philip math’s memory fresh. So the poly- Anderson, summarized Young’s math gets forgotten or, at best, achievements as follows: squashed into a category we can recognize, in the way Goethe is He elucidated the optics of the eye, remembered as a poet, despite his the wave theory of light, the laws of claim to have been a scientist, or elasticity, the nature of the Egyptian Hume as a philosopher, for all the six hieroglyphic writing, and Lord knows dumpy volumes of his History of Eng- how many other subjects. land. [Yet,] There are times when a mind of exceptional range, bestriding Among non-scientists, Young’s many conventional disciplines, makes position has been less secure. His a breakthrough in each because he reputation, like those of Robert knows the others, and all of them go Hooke, Benjamin Franklin and on their way, afterwards, without Alexander von Humboldt, has suf- necessarily recognizing what he did or fered from his being a polymath. how he did it. If history is not to be Polymathy is disturbing, especially to chronically misremembered, it follows specialists, as historian Alexander that a constant effort must be made – Murray noted in connection with Sir as constant as the mechanism that William ‘Oriental’ Jones (1746-94), a pulls invisibly in the other direction – Calculations from the Nautical Almanac polymath of the generation before to recall those polymathic minds that of 1822, for which Young acted as Young’s. Jones is primarily remem- have made these critical turns. superintendent (i.e. chief calculator). 54 HISTORY TODAY APRIL 2006 major supplement to the Encyclopae- ‘Scientific researches! – new discoveries Young his due, admits: dia Britannica in 1815-19. While pay- in pneumaticks! – or an experimental ing generous tribute to Champol- lecture on the powers of air’, published ... the suspicion may easily arise, and lion’s unrivalled progress from 1822 in May 1802 by James Gillray, probably often has done, that any eulogy of onwards, Young wanted his early shows Young, watched by Humphry Thomas Young must be intended as a steps recognized.
Recommended publications
  • Significance of Beating Observed in Earthquake Responses of Buildings
    SIGNIFICANCE OF BEATING OBSERVED IN EARTHQUAKE RESPONSES OF BUILDINGS Mehmet Çelebi1, S. Farid Ghahari2, and Ertuğrul Taciroǧlu2 U.S. Geological Survey1 and University of California, Los Angeles2 Menlo Park, California, USA1 and Los Angeles, California, USA2 Abstract The beating phenomenon observed in the recorded responses of a tall building in Japan and another in the U.S. are examined in this paper. Beating is a periodic vibrational behavior caused by distinctive coupling between translational and torsional modes that typically have close frequencies. Beating is prominent in the prolonged resonant responses of lightly damped structures. Resonances caused by site effects also contribute to accentuating the beating effect. Spectral analyses and system identification techniques are used herein to quantify the periods and amplitudes of the beating effects from the strong motion recordings of the two buildings. Quantification of beating effects is a first step towards determining remedial actions to improve resilient building performance to strong earthquake induced shaking. Introduction In a cursory survey of several textbooks on structural dynamics, it can be seen that beating effects have not been included in their scopes. On the other hand, as more earthquake response records from instrumented buildings became available, it also became evident that the beating phenomenon is common. As modern digital equipment routinely provide recordings of prolonged responses of structures, we were prompted to visit the subject of beating, since such response characteristics may impact the instantaneous and long-term shaking performances of buildings during large or small earthquakes. The main purpose in deploying seismic instruments in buildings (and other structures) is to record their responses during seismic events to facilitate studies understanding and assessing their behavior and performances during and future strong shaking events.
    [Show full text]
  • On an Experimentum Crucis for Optics
    Research Report: On an Experimentum Crucis for Optics Ionel DINU, M.Sc. Teacher of Physics E-mail: [email protected] (Dated: November 17, 2010) Abstract Formulated almost 150 years ago, Thomas Young’s hypothesis that light might be a transverse wave has never been seriously questioned, much less subjected to experiment. In this article I report on an attempt to prove experimentally that Young’s hypothesis is untenable. Although it has certain limitations, the experiment seems to show that sound in air, a longitudinal wave, can be “polarized” by reflection just like light, and this can be used as evidence against Young’s hypothesis. Further refinements of the experimental setup may yield clearer results, making this report useful to those interested in the important issue of whether light is a transverse or a longitudinal wave. Introduction In the course of development of science, there has always been a close connection between sound and light [1]. Acoustics stimulated research and discovery in optics and vice-versa. Reflection and refraction being the first common points observed between the two, the analogy between optical and acoustical phenomena has been proven also in the case of interference, diffraction, Doppler effect, and even in their mode of production: sounds are produced by the vibration of macroscopic objects, while light is produced by vibrating molecules and atoms. The wave nature of sound implies that light is also a wave and, if matter must be present for sound to be propagated, then aether must exist in order to account for the propagation of light through spaces void of all the matter known to chemistry.
    [Show full text]
  • Helmholtz's Dissonance Curve
    Tuning and Timbre: A Perceptual Synthesis Bill Sethares IDEA: Exploit psychoacoustic studies on the perception of consonance and dissonance. The talk begins by showing how to build a device that can measure the “sensory” consonance and/or dissonance of a sound in its musical context. Such a “dissonance meter” has implications in music theory, in synthesizer design, in the con- struction of musical scales and tunings, and in the design of musical instruments. ...the legacy of Helmholtz continues... 1 Some Observations. Why do we tune our instruments the way we do? Some tunings are easier to play in than others. Some timbres work well in certain scales, but not in others. What makes a sound easy in 19-tet but hard in 10-tet? “The timbre of an instrument strongly affects what tuning and scale sound best on that instrument.” – W. Carlos 2 What are Tuning and Timbre? 196 384 589 amplitude 787 magnitude sample: 0 10000 20000 30000 0 1000 2000 3000 4000 time: 0 0.23 0.45 0.68 frequency in Hz Tuning = pitch of the fundamental (in this case 196 Hz) Timbre involves (a) pattern of overtones (Helmholtz) (b) temporal features 3 Some intervals “harmonious” and others “discordant.” Why? X X X X 1.06:1 2:1 X X X X 1.89:1 3:2 X X X X 1.414:1 4:3 4 Theory #1:(Pythagoras ) Humans naturally like the sound of intervals de- fined by small integer ratios. small ratios imply short period of repetition short = simple = sweet Theory #2:(Helmholtz ) Partials of a sound that are close in frequency cause beats that are perceived as “roughness” or dissonance.
    [Show full text]
  • Neural Tracking of the Musical Beat Is Enhanced by Low-Frequency Sounds
    Neural tracking of the musical beat is enhanced by low-frequency sounds Tomas Lenca, Peter E. Kellera, Manuel Varleta, and Sylvie Nozaradana,b,c,1 aMARCS Institute for Brain, Behaviour, and Development, Western Sydney University, Penrith, NSW 2751, Australia; bInstitute of Neuroscience (IONS), Université Catholique de Louvain, 1200 Woluwe-Saint-Lambert, Belgium; and cInternational Laboratory for Brain, Music, and Sound Research (BRAMS), Département de Psychologie, Faculté des Arts et des Sciences, Université de Montréal, Montréal, QC H3C 3J7, Canada Edited by Dale Purves, Duke University, Durham, NC, and approved June 28, 2018 (received for review January 24, 2018) Music makes us move, and using bass instruments to build the content (8, 9). Bass sounds are also crucial in music that en- rhythmic foundations of music is especially effective at inducing courages listeners to move (10, 11). people to dance to periodic pulse-like beats. Here, we show that There has been a recent debate as to whether evolutionarily this culturally widespread practice may exploit a neurophysiolog- shaped properties of the auditory system lead to superior tem- ical mechanism whereby low-frequency sounds shape the neural poral encoding for bass sounds (12, 13). One study using elec- representations of rhythmic input by boosting selective locking to troencephalography (EEG) recorded brain responses elicited by the beat. Cortical activity was captured using electroencephalog- misaligned tone onsets in an isochronous sequence of simulta- raphy (EEG) while participants listened to a regular rhythm or to a neous low- and high-pitched tones (12). Greater sensitivity to the relatively complex syncopated rhythm conveyed either by low temporal misalignment of low tones was observed when they tones (130 Hz) or high tones (1236.8 Hz).
    [Show full text]
  • Large Scale Sound Installation Design: Psychoacoustic Stimulation
    LARGE SCALE SOUND INSTALLATION DESIGN: PSYCHOACOUSTIC STIMULATION An Interactive Qualifying Project Report submitted to the Faculty of the WORCESTER POLYTECHNIC INSTITUTE in partial fulfillment of the requirements for the Degree of Bachelor of Science by Taylor H. Andrews, CS 2012 Mark E. Hayden, ECE 2012 Date: 16 December 2010 Professor Frederick W. Bianchi, Advisor Abstract The brain performs a vast amount of processing to translate the raw frequency content of incoming acoustic stimuli into the perceptual equivalent. Psychoacoustic processing can result in pitches and beats being “heard” that do not physically exist in the medium. These psychoac- oustic effects were researched and then applied in a large scale sound design. The constructed installations and acoustic stimuli were designed specifically to combat sensory atrophy by exer- cising and reinforcing the listeners’ perceptual skills. i Table of Contents Abstract ............................................................................................................................................ i Table of Contents ............................................................................................................................ ii Table of Figures ............................................................................................................................. iii Table of Tables .............................................................................................................................. iv Chapter 1: Introduction .................................................................................................................
    [Show full text]
  • The Concept of the Photon—Revisited
    The concept of the photon—revisited Ashok Muthukrishnan,1 Marlan O. Scully,1,2 and M. Suhail Zubairy1,3 1Institute for Quantum Studies and Department of Physics, Texas A&M University, College Station, TX 77843 2Departments of Chemistry and Aerospace and Mechanical Engineering, Princeton University, Princeton, NJ 08544 3Department of Electronics, Quaid-i-Azam University, Islamabad, Pakistan The photon concept is one of the most debated issues in the history of physical science. Some thirty years ago, we published an article in Physics Today entitled “The Concept of the Photon,”1 in which we described the “photon” as a classical electromagnetic field plus the fluctuations associated with the vacuum. However, subsequent developments required us to envision the photon as an intrinsically quantum mechanical entity, whose basic physics is much deeper than can be explained by the simple ‘classical wave plus vacuum fluctuations’ picture. These ideas and the extensions of our conceptual understanding are discussed in detail in our recent quantum optics book.2 In this article we revisit the photon concept based on examples from these sources and more. © 2003 Optical Society of America OCIS codes: 270.0270, 260.0260. he “photon” is a quintessentially twentieth-century con- on are vacuum fluctuations (as in our earlier article1), and as- Tcept, intimately tied to the birth of quantum mechanics pects of many-particle correlations (as in our recent book2). and quantum electrodynamics. However, the root of the idea Examples of the first are spontaneous emission, Lamb shift, may be said to be much older, as old as the historical debate and the scattering of atoms off the vacuum field at the en- on the nature of light itself – whether it is a wave or a particle trance to a micromaser.
    [Show full text]
  • Quantum Weirdness: a Beginner's Guide
    Quantum Weirdness: A Beginner’s Guide Dr. Andrew Robinson Part 1 Introduction The Quantum Jump 9:38 AM About Me • From Bakewell • PhD in Physical Chemistry • Worked in Berlin, Liverpool, Birmingham • In Canada since 2000 • Worked at University of Saskatchewan • Moved to Ottawa in 2010 • Teach Physics at Carleton 9:38 AM In This Lecture Series • We will talk about • What does Quantum Mean? • Quantum Effects • What are the ramifications of Quantum Theory • How Quantum Theory impacts our everyday lives • I will show a few equations, but you don’t need to know any mathematics • Please ask questions at any time 9:38 AM Books “How to Teach Quantum Physics to your Dog” by Chad Orzel “30-Second Quantum Theory” By Brian Clegg (ed.) 9:38 AM Definition of “Quantum” Physics • A discrete quantity of energy proportional in magnitude to the frequency of the radiation it represents. Legal • A required or allowed amount, especially an amount of money legally payable in damages. 9:38 AM • Quantum Satis “as much as is sufficient“ – pharmacology and medicine • Quantum Salis “the amount which is enough” • Quantum comes from the Latin word quantus, meaning "how great". Used by the German Physicist Hermann von Helmholtz ( who was also a physician) in the context of the electron (quanta of electricity) Use by Einstein in 1905 "Lichtquanta” – particle of light 9:38 AM “Quantum Jump” & “Quantum Leap” • Colloquially “A sudden large increase or advance”. • In physics “A jump between two discrete energy levels in a quantum system” (Actually a rather small leap in terms of energy!) 9:38 AM Quantum Properties in Physics • Properties which can only take certain values When you are on the ladder, you must be on one of the steps: 4 1 3 2 Quantum 2 3 Numbers 1 4 9:38 AM • Not every quantity in physics is quantized • Your height from the ground when on the slide varies continuously Maximum height Minimum9:38 AM height • Whether you can treat the system as continuous, or quantum depends on the scale.
    [Show full text]
  • Thomas Young's Research on Fluid Transients: 200 Years On
    Thomas Young's research on fluid transients: 200 years on Arris S Tijsseling Alexander Anderson Department of Mathematics School of Mechanical and Computer Science and Systems Engineering Eindhoven University of Technology Newcastle University P.O. Box 513, 5600 MB Eindhoven Newcastle upon Tyne NE1 7RU The Netherlands United Kingdom ABSTRACT Thomas Young published in 1808 his famous paper (1) in which he derived the pressure wave speed in an incompressible liquid contained in an elastic tube. Unfortunately, Young's analysis was obscure and the wave speed was not explicitly formulated, so his achievement passed unnoticed until it was rediscovered nearly half a century later by the German brothers Weber. This paper briefly reviews Young's life and work, and concentrates on his achievements in the area of hydraulics and waterhammer. Young's 1808 paper is “translated” into modern terminology. Young's discoveries, though difficult for modern readers to identify, appear to include most if not all of the key elements which would subsequently be combined into the pressure rise equation of Joukowsky. Keywords waterhammer, fluid transients, solid transients, wave speed, history, Thomas Young NOTATION c sonic wave speed, m/s p fluid pressure, Pa D internal tube diameter, m R internal tube radius, m E Young’s modulus, Pa t time, s e tube wall thickness, m v velocity, m/s f elastic limit, Pa x length, m g gravitational acceleration, m/s 2 δ change, jump h height, pressure head, m ε longitudinal strain K fluid bulk modulus, Pa ρ mass density, kg/m
    [Show full text]
  • Three Music-Theory Lessons
    Three Music-Theory Lessons The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Rehding, Alexander. 2016. “Three Music-Theory Lessons.” Journal of the Royal Musical Association 141 (2) (July 2): 251–282. doi:10.1080/02690403.2016.1216025. Published Version doi:10.1080/02690403.2016.1216025 Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:34220771 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#OAP Three Music Theory Lessons ALEXANDER REHDING To make the familiar strange and the strange familiar was as much a central feature of Novalis’ conception of Romanticism as it is a mainstay of semiotics.1 In this spirit, we will begin with what seems like a mundane description of music- theoretical practice. If we enter a music theory classroom in the western world, we would normally expect to find a number of objects. We see a blackboard, ideally with five-line staffs already printed on it. We also expect a piano in the room, and we would probably have some sheet music, perhaps with the quintessential music theory teaching material: Bach chorale harmonizations. Let’s further imagine it is this passage, the simple opening line of the Lutheran hymn “Wie schön leuchtet der Morgenstern,” from Bach’s Cantata BWV 1, shown in Fig. 1, that is marked on the board.
    [Show full text]
  • PSYCHOACOUSTICS: Software Package for Psychoacoustics
    Acoust. Sci. & Tech. 41, 1 (2020) #2020 The Acoustical Society of Japan INVITED REVIEW PSYCHOACOUSTICS: Software package for psychoacoustics Aleksander P. Se˛k1;Ã and Brian C. J. Moore2;y 1Institute of Acoustics, Faculty of Physics, Adam Mickiewicz University, Poznan´, Poland 2Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, United Kingdom Abstract: Current research in the field of psychoacoustics is mostly conducted using a computer to generate and present the stimuli and to collect the responses of the subject. However, writing the computer software to do this is time-consuming and requires technical expertise that is not possessed by many would-be researchers. We have developed a software package that makes it possible to set up and conduct a wide variety of experiments in psychoacoustics without the need for time-consuming programming or technical expertise. The only requirements are a personal computer (PC) with a good- quality sound card and a set of headphones. Parameters defining the stimuli and procedure are entered via boxes on the screen and drop-down menus. Possible experiments include measurement of the absolute threshold, simultaneous and forward masking (including notched-noise masking), comodu- lation masking release, intensity and frequency discrimination, amplitude-modulation detection and discrimination, gap detection, discrimination of interaural time and level differences, measurement of sensitivity to temporal fine structure, and measurement of the binaural masking level difference. The software is intended to be useful both for researchers and for students who want to try psychoacoustic experiments for themselves, which can be very valuable in helping them gain a deeper understanding of auditory perception.
    [Show full text]
  • Musical Acoustics Timbre / Tone Quality I
    Musical Acoustics Lecture 13 Timbre / Tone quality I Musical Acoustics, C. Bertulani 1 Waves: review distance x (m) At a given time t: y = A sin(2πx/λ) A time t (s) -A At a given position x: y = A sin(2πt/T) Musical Acoustics, C. Bertulani 2 Perfect Tuning Fork: Pure Tone • As the tuning fork vibrates, a succession of compressions and rarefactions spread out from the fork • A harmonic (sinusoidal) curve can be used to represent the longitudinal wave • Crests correspond to compressions and troughs to rarefactions • only one single harmonic (pure tone) is needed to describe the wave Musical Acoustics, C. Bertulani 3 Phase δ $ x ' % x ( y = Asin& 2π ) y = Asin' 2π + δ* % λ( & λ ) Musical Acoustics, C. Bertulani 4 € € Adding waves: Beats Superposition of 2 waves with slightly different frequency The amplitude changes as a function of time, so the intensity of sound changes as a function of time. The beat frequency (number of intensity maxima/minima per second): fbeat = |fa-fb| Musical Acoustics, C. Bertulani 5 The perceived frequency is the average of the two frequencies: f + f f = 1 2 perceived 2 The beat frequency (rate of the throbbing) is the difference€ of the two frequencies: fbeats = f1 − f 2 € Musical Acoustics, C. Bertulani 6 Factors Affecting Timbre 1. Amplitudes of harmonics 2. Transients (A sudden and brief fluctuation in a sound. The sound of a crack on a record, for example.) 3. Inharmonicities 4. Formants 5. Vibrato 6. Chorus Effect Two or more sounds are said to be in unison when they are at the same pitch, although often an OCTAVE may exist between them.
    [Show full text]
  • The Perception of Pure and Mistuned Musical Fifths and Major Thirds: Thresholds for Discrimination, Beats, and Identification
    Perception & Psychophysics 1982,32 (4),297-313 The perception ofpure and mistuned musical fifths and major thirds: Thresholds for discrimination, beats, and identification JOOS VOS Institute/or Perception TNO, Soesterberg, TheNetherlands In Experiment 1, the discriminability of pure and mistuned musical intervals consisting of si­ multaneously presented complex tones was investigated. Because of the interference of nearby harmonics, two features of beats were varied independently: (1) beat frequency, and (2) the depth of the level variation. Discrimination thresholds (DTs) were expressed as differences in level (AL) between the two tones. DTs were determined for musical fifths and major thirds, at tone durations of 250, 500, and 1,000 msec, and for beat frequencies within a range of .5 to 32 Hz. The results showed that DTs were higher (smaller values of AL) for major thirds than for fifths, were highest for the lowest beat frequencies, and decreased with increasing tone duration. Interaction of tone duration and beat frequency showed that DTs were higher for short tones than for sustained tones only when the mistuning was not too large. It was concluded that, at higher beat frequencies, DTs could be based more on the perception of interval width than on the perception of beats or roughness. Experiments 2 and 3 were designed to ascertain to what extent this was true. In Experiment 2, beat thresholds (BTs)for a large number of different beat frequencies were determined. In Experiment 3, DTs, BTs, and thresholds for the identifica­ tion of the direction of mistuning (ITs) were determined. For mistuned fifths and major thirds, sensitivity to beats was about the same.
    [Show full text]