达德尔的实验揭示，碳弧灯的杂音，源于电弧的非线性特性所导致的负阻（negative resistance）现象。负阻现象早在1898年由赫尔曼·西奥多·西蒙（Hermann Theodor Simon，德国法兰克福）博士所记录。Simon, H.T. (1989), “Akustische Erscheinungen am electrischen Flammenbogen,” Ann. Physik 300, # 2, pp 233–9.西蒙博士注意到，调制电弧的供电电压，可以控制电弧“唱歌”。他还展示了电弧的另一个功能——他曾对公众做过一个演示，将电弧作为一个高效的扬声器。（西蒙的实验同时提到，经过调制的电弧不仅能产生声音，还能产生经过调制的光线；利用这一特性，德国海军使用改造的探照灯和光敏硒电池，成功地完成了舰船之间的电话通信。Wittje, R. (2013), ‘The electrical imagination sound analogies, equivalent circuits, and the rise of electroacoustics, 1863-1939′, Osiris, Vol 28 #1, pp 40-63）
达德尔很可能了解到了西蒙的相关研究。他在碳弧电极上加入了LC共振电路，尝试通过这种方法解决噪音问题；这么一来，他创造了一台可调音的振荡器。达德尔又将一个可控制输入电压的键盘连到电路上——一台最早的电子乐器就此诞生。达德尔的这个发明是历史上唯一一台使用电弧（作为音源）产生声音的电子乐器，也是第一台不经放大器、扬声器或电话系统（当时这些放大设备还未发明出来）作为放大装置，就能听到声音的电子乐器。Duddell, W. (1900), ‘Some Experiments on the Direct-Current Arc’, Nature, vol. 63, no. 1625 (December 20, 1900), pp. 182-183.达德尔还使用了火花隙（spark gap）放大技术，尝试使用可变电阻或麦克风传递电弧产生的声音；这说明在真空管还未发明的时候，同样可以长距离传输、放大电话或电路的语音。Wittje, R. (2013), ‘The electrical imagination sound analogies, equivalent circuits, and the rise of electroacoustics, 1863-1939′, Osiris, Vol 28 #1, p 52
视频：2016年，意大利科技基金会（Fondazione Scienza e Tecnica）尝试复原达德尔和赫尔曼·西奥多·西蒙（Hermann Theodor Simon）发明的“歌弧琴”
当达德尔向伦敦电气工程师学会（London institution of Electrical Engineers）展出这部乐器时，工程师们发现，其他建筑中在与这部乐器处于同一电路的电灯也开始发出和这台乐器一样的声音来；人们据此推测，音乐可以通过照明电路传输。
赫尔曼·亥姆霍兹（Hermann von Helmholtz）著《论作为音乐理论生理基础的音感》（On the Sensations of Tone，1862）的英文译本在1885年一经发行，立即对当时的科学、音乐思想流派产生了深远影响。根据亥姆霍兹定义的概念，一种声音（tone）是由一个基本音（fundamental sound）和一组更高的声音结合组成的，这种组合赋予每一种声音独特的音色质感——而声音则是许多“纯”正弦波声音组成的。卡希尔据此推理，认为可以制造一台产生许多正弦波声音的“完美乐器”，通过组合这些正弦波来“无瑕疵地”重现以往乐器的声音。
电传簧风琴的键盘结构相比则有些让人感到陌生。在第二台电传簧风琴上，卡希尔邀请了钢琴家埃德温·霍尔·皮尔斯（Edwin Hall Pierce）设计乐器的功能（repertoire），利用多层泛音制造音色。皮尔斯和卡希尔同时也确定了这台乐器与众不同的键盘结构。电传簧风琴通过精确的音高分段产生声音，因为这种分段基本可视为平均律，皮尔斯决定在乐器上使用三组键盘（后期的电传簧风琴型号也有使用两组或四组键盘的），因此，这台乐器的每个八度可以有36个琴键（整个三组键盘）——这意味着这台乐器的键盘与平常的黑白琴键不同，它拥有更多的黑键白键；演奏者必须学习在这三层键盘上如何演奏平均律制。虽然电传簧风琴这复杂的键盘简直就是噩梦，但不可否认的是，电传簧风琴因此具有了独特的功能：如果需要的话，它可以演奏多种调性律制（intonation）的音乐。
这台乐器还具备一个类似离合器的装置，通过这个装置，演奏者可使用踏板、击键速度来控制音色表情。乐器输出的声音通过有线网络传输至听众那里。在听众一端，声音最终从一个大型的、设计多样的六英尺声号筒（acoustic horn）中传出，卡希尔测试了众多不同材质的声号筒设计，包括不同厚度的木材、碳钢（metal carbon）以及纸材，以便获得正确的声域（range of tones）。
对于电传簧风琴来说，声音要想要被电话接收机以外的东西所感知，必须要借助比普通电话更大的电流。电传簧风琴起电机的输出功率高达15,000瓦特，在接收端电流大概在1安培左右；相比之下，一台电话接收机的设计电流仅仅是这个数字的六千亿分之一原文为“six ten-trillionths of an amp”，以为讹误。——译者注。电传簧风琴的功率的确能让听众清晰地听到音乐，但同时也导致乐器与纽约的电话网络相冲突，与此同时，要运行整个系统，也需要耗费巨量电力。
卡希尔随后在电传簧风琴音乐厅（Telharmonic Hall）建立了纽约电子音乐公司（New York Electric Music Co.），从1906年开始传送了多期电传簧风琴音乐活动————其中还包括簧风琴地下室装备参观。音乐节目由几补流行轻古典作品组成，可着重展示乐器的音域及灵活性。节目的听众通过许多的声号筒、扬声器收听音乐，音乐同时还会传输到碳弧灯上，碳弧灯受电信号震荡而闪动，形成了声光演出（英国物理学家威廉姆·达德尔曾探索过这个现象，并在1899年发明的“歌弧琴”中利用了这一原理）。
THE TELHARMONIUM – AN APPARATUS FOR THE ELECTRICAL GENERATION AND TRANSMISSION OF MUSIC.
Dr. Thaddeus Cahill’s system of generating music at a central station in the form of electrical oscillations, and of transmitting these oscillations by means of wires to any desired point, where they are rendered audible by means of an ordinary telephone receiver or a speaking arc, is now embodied in a working plant situated in the heart of New York. Although this apparatus constitutes b.ut a portion of a plant that may ultimately assume very remarkable dimensions, and although it has limitations imposed by its size, the results obtained are so promising, that many applications have been made by prospective subscribers for connection with the central station. When a larger number of · generators and keyboards is installed, as they doubtless will be in due time, there is no reason why the telharmonium, as the invention is called, should not give the subscribers all the pleasures of a full symphony orchestra whenever they wish to enjoy them. At present ‘ very beautiful effects are secured on a . less elaborate scale, but in eveI\ly way comparable with those of a good quintet.. And several additional keyboards now in building at Dr. Cahill’s works at Holyoke, Mass., where the New York plant was built, are nearing completion, and will probably be in service at Broadway and Thirty-ninth Street in the course of another month or two.
Perhaps the feature which most astonishes the technically Uninformed man when Dr. Cahill’s invention is first exhibited to him is the fact that music in the ordinary sense of the word, in other words, rhythmic vibrations of the air, is not produced at the central station. The vibrant notes of the flute, mingled with the clarinet or viol-like tones which are heard at the receiving end of the wire, spring from no musical instrument whatever. Nowhere is anything like a telephone transmitter used, although the electrical oscillations which are sent to the receiver and there translated into audible vibrations are quite like those set up in an ordinary telephone circuit, except that they are enormously more powerful.
Briefly summed up, Dr. Cahill’s wonderful invention consists in generating electrical oscillations corresponding in period with the acoustic vibrations of the various elemental tones desired, in synthesizing from th ese electrical vibrations the different notes and chords required, and in rendering the sYnthesized electrical vibrations audible by a translating device.
In the New York plant the electrical vibrations are produced by 144 alternating dynamos of the inductor type, having frequencies that vary from 40 to 4,000 cycles. These alternators are arranged in eight sections or panels, each inductor being mounted on an ll-inch steel shaft. One inductor dynamo is used for each note of the musical scale, each generator producing as many electrical vibrations per second as there are aerial vibrations in that note of the musical scale for which it stands. The fixed or stator part of each dynamo carries both the field and armature windings ; the rotors are carried on shafts geared together, the number of teeth ( pole pieces) on the gear wheels corresponding with the number of frequencies to be ob-. tained. Because the rotors are geared together, the frequencies are fixed and tuning is unnecessary. The alternators are controlled each by a key in a keyboard upon which the musician plays. Each key serves to make and break the main eircuit from seven alternators, not directly, but through the medium of plunger relay magnets wound with layers of enameled wire. Only feeble and harmless currents are needed to control the relay magnets, by which the task of making and breaking the currents from the main circuits is r’eally performed. No appreciable ‘ time elapses between the depression of a key and the closing of a main alternating circuit, so that the keyboard is as responsive and sensitive as that of a piano. The elemental notes generated by the . 144 dynamos cannot alone be used to produce the most pleasing musical effects.
Why this should be so becomes apparent from a consideration of some Simple principles in acoustics. If a wire be stretched between two points A and B (see the accompanying diagram) and plucked or struck, it will vibrate above and below the line A, B and give what is known as a fundamental tone. This fundamental tone is without distinctive musical character or timbre, and would sound the same in all instruments, so that one could not distinguish whether it came from a violin or a piano. In addition to its fundamental vibration between its pOints of attachment, the string undergoes a series of sub-vibrations above and below its own normal curve, which it will pass at certain points, nodes, dividi????g it into equal parts. Thus in the accompanying sketch, A, 0, B and A, D, B represent the fundamental Vibrations, and A, E, 0, F, B, the first sub-vibration intersecting the fundamental vibration at the node 0. Again, the string may vibrate in three parts, four parts, five parts, etc. The effect of the sub-vibrations is added to the effect of the fundamental vibration, and their total effect is heard in the distinctive quality or “tone Color,” as it is called, of the particular instrument played. The sub-vibrations are known as the upper partials or overtones, and generally speaking, they are harmonious with one another and with the fundamental tone. That very elusive and uncertain quality called timbre is dependent entirely upon these overtones. By properly controlling the blending of the overtones and the elemental tones, it ought to be possible to. imitate the characteristic timbre of any musical instrument. This Dr. Cahill has in a large measure succeeded in accomplishing.
“Tone mixing,” as this building up of harmonious notes and chords is called, is effected in the telharmonium by superposing the simple or sinusoidal waves of the alternators. By means of bus-bars the oscillations of the ground tones are all brought together in one circuit, those of the first partials in another circuit, those of the second partials in a third circuit, etc. The actual blending is done by passing the various oscillations through a series of transformers. In order to understand how a chord is blended, we must begin at the keyboard. As soon as the performer depresses his keys, the bus-bars electrically superpose the ground tone currents , through the primaries of closed-iron magnetic circuit transformers, the secondaries of which are jained in circuit with impedance rheostats governing the strength of the currents, which rheostats are controlled from the keyboard by means of stops. Similarly the bus-bars superpose the first, second, third, and other desired partials in separate circuits. The composite ground-tone a’nd overtone oscillations thus produced in the secondaries of the transformers are next passed through the primaries of an open-iron magnetic circuit transformer, in the secondary circuit of which a current is produced composed of all the ground tone and overtone frequencies of the particular chord under consideration. This secondary current is in turn passed through the primary of an air-core transformer, and the resultant secondary current is converted by telephone receivers or speaking arcs into the musical chord desired.
In order to listen to this musical chord, the telephone receiver is not held to the ear. It would be bad for the ear if it were, when a loud note is sounded. The current of the receiver is literally thousands, and at times millions of times stronger, measured in watts, than those to which an ordinary telephone receiver responds. Whereas less than six tenmillionths of an ampere are sufficient to produce a response from an ordinary telephone receiver, a current of an ampere is sometimes used in the Cahill system for an instant when loud tones are produced.
The composition or quality of a note or chord is controlled by eight rheostats called stops. By skillful manipulation of the stop rheostats, it is possible to obtain very accurate imitations of the wood-winds and several other orchestral instruments. Imitation, however, is hardly the right word ; for the notes are built up of exactly the same components as the tones which come from the reaJ instruments. Furthermore, beautiful effects are obtained that cannot be produced on any existing instrument. These stop rheostats control merely the timbre or quality of the music produced. Fluctuations in volume are produced by “expression rheostats.” Both stop and expression rheostats are constituted by impedance coils, differing however in mechanical construction. The stop rheostats are manipulated very much like the stops of an organ, and the expression rheostats like the swell. Unlike an organ swell, however, the expression rheostats are used not only for producing captivating crescendos and diminuendos of individual notes and chords, but also in reproducing the peculiar singing tremolo of the violin and ‘cello.
The rather complex system of transformers described serves not merely to blend partials with ground tones, but also to purify the vibrations corresponding with the different sets of partials by purging them of their harsher components. The air core transformers, fur thermore, permit the selection of voltages according to the resistance which the final current will encounter. Inasmuch as each keyboard controls ground-tone and overtone mixing devices, it is possible to produce notes of the same timbre or of different timbres. Excellent orchestral effects can, therefore, be obtained by causing the one keyboard to sound wind instruments, such as oboes, flutes, clarinets, or horns, and the other to sound the tones of the violin or other stringed instruments.
From this necessarily cursory consideration of the telharmonium, it is evident that the music is initiated as electrical vibrations, distributed in the form of electricity, and finally converted into aerial vibrations at a thousand different places separated hundreds of miles, it may be. No musical instruments in the sense in which we understand the word are used. Not a string, reed, or pipe is anywhere to be found. The vibrations produced by the performers’ playing are wholly electrical, and not until they reach the telephone receiver can they be heard. The telephone reo ceiver acts for us as a kind of electrical ear to hear oscillations to which our own ears are insensitive. When Mark Twain heard the telharmonium, he fancifully suggested that the military parade’ of the future would be a more beautifully rhythmic procession than our present pageants. The usual military bands heading the various regiments and playing marches, not in unison, although the same in time, will give place to musical arcs disposed along the line of march, all crashing out their stntins in perfect time. The soldiers who will march in that future parade win all hear the blare of invisible electrical trumpets and horns at the same moment; they will all raise their left feet at exactly the same instant, just as if they were but one company.
So far as the capabilities of the telharmonium are concerned, it may be stated that the New York installation is able to supply ten thousan-d subscribers, or more, with music of moderate volume at widely remote places. The very remarkable and rapid development of the invention has been thus eloquently set forth by Prof. A. S. McAllister in an article published in the Electrical World :
“From Hero, who first proposed to utilize the motive power of steam, to Watt’s first successful engine, was almost two thousand years. And between the proposal of Hero and the accGmplishment of Watt many inventors in different countries made ineffective attempts to attain the goal desired. From Huyghens’s proposal of an explosive motor to Otto’s successful machine two centuries elapsed, with scores of patents in the different countries of Europe. So from Sir Humphry Davy’s experimental arc to the Brush and Edison arc lighting machines” three-quarters of a century elapsed, during which scores of inventors in different countries endeavored to solve the problem in vain. Similar remarks apply to the progress of most great inventions, electri· cal and mechanical. But the process of producing music from dynamos has been carried from the first conception to the successful working machine by one man-Thaddeus Cahill-in a few years. And when one hears the plant at Thirty-ninth Street and Broadway, with its musical tones already equaling, if not surpassing, the instruments of the orchestra, one wonders what cannot be expected in a few years to come when the inventor will have had time to do his best, and when his work in all its details will be known ·to the world and open to improvement by others, and when musicians will have learned to use the new powers which electricity is placing at their command. Clearly the world has, through the wonderful powers of the electrical forces and the skillful use made of them by Dr. Cahill, a new music, a music which can be produced in many thousand places simultaneously, and which in its very infancy seems destined to surpass in sympathy and responsiveness-in artistic worth-the existing music of pipe and string, the evolution of many centuries.”
From ‘Scientific American’ vol 96 #10 9th March 1907
（Robert A. Moog,”ElectronicMusic,”Journal of the Audio Engineering Society, October/November 1977, 25:10/11, 856.）
贝克尔在《麦克卢尔》杂志上的文章《旧世界，新音乐》（New Music for an Old World）得到了鲁西奥·布索尼（Ferruccio Busoni）的注意。这位意大利艺术大师、古典钢琴家、批判知识分子曾在1907年《新式音乐美学导论》（Sketch of a New Aesthetic of Music）中表达了对电传簧风琴的关注。他提出了一种基于渐进音符（infinite gradations of tone）的音乐结构，用以超越原有的12音体系以及传统的管弦乐团配器：
“谁不曾梦想遨游天际，并笃信梦想会化作现实？让我们想想，音乐要怎样才能回复其原始、自然的本源；让我们将音乐从结构化（archectonic）、原声声学、美学的绳墨中解放出来；让音乐成为和声、形式与音色意义上纯粹的创造、情感表达（sentiment）（因为创造与情感表达并不是只有音乐才能做到）；让音乐跟随彩虹的线条，与云朵间隙投射的阳光竞彩；让音乐成为单纯从人类胸怀映射自然的工具；对于音乐来说，它就是漂浮天际之上的“声音大气”；而对我们自身来说，人随时出现在创作过程中（Creation entire），是绝对的主体原文为“within Man himself as universally and absolutely as in Creation entire”。——译注……”
如果以利沙·格雷（Elisha Gray）比亚历山大·格雷厄姆·贝尔（Alexander Graham Bell）早一个小时到达专利局，他就会成为今天人们所熟知的“电话之父”。但是，他却意外地在历史中留下足迹，成为了第一个电子乐器的发明人。格雷曾偶然见到他的侄子在摆弄他的器材——这个孩子把一块电池一端连接到自己身上，另一端则连到浴缸中；用手摩擦浴缸表面，浴缸会发出与电流成比例变化的声响——受此启发，他开始进行电子声学效应的研究。
THE TELEPHONE EXHIBITION AT LINCOLN HALL. ________
Airs Played In Philadelphia Distinctly Audible In Washington–Description of the Apparatus–Its Sound and What It Resembles–The Performance a Great Success.
The atmospheric conditions last evening were far from favorable to the reception of music by telegraph, and it was not surprising, therefore, that the majority of those who went to Lincoln hall last evening to presence the latest triumph of American science–the telephone–were more or less doubtful of the success of the experiment they were about to witness. The interest manifested by our citizens in this grand and important invention could not have been attested in a more substantial manner, for the hall was filled to almost its amplest capacity by as intelligent and discriminating an audience as has gathered in that resort this season.
The preparation for the exhibition of the telephone were quite simple and were easily observable. Several wires depended from the aperture over the chandelier in the centre of the room, and communicated some with a regular telegraphic instrument on the stage to the left of the audience, others with the receiving apparatus of the telephone. The latter was placed on the floor of the stage, to the right of the audience. It is a small apparatus, about six feet long and less than two feet high, and consists of sixteen square boxes, resembling in appearance and arrangement the tubes of a large organ.
The entertainment began with the concert which Mr. Maurice Strakosch had provided, evidently to offset any disappointment that the audience might experience in the event of the inability of the telephone to surmount the obstacles of the inclement weather. The following was the programme:
Miss Fannie Kellogg is a young lady of prepossessing appearance, but evidently still a novice in the concert-room. Her rendition of the Polonaise from “Mignon,” which is an extremely difficult passage, requiring the greatest flexibility and control of voice, was not even a mediocre performance, although she took the liberty of omitting the trills and substituting a few notes of her own for those of the composer, and to cap the climax the finale of the air was sang entirely out of key as well as out of time. Indeed, it was as complete a faux pas as we have ever witnessed at a first-class concert. Miss Kellogg, nevertheless, found many admirers, for she was loudly encored, and in response to repeated calls essayed that sweet and plaintive air of Apt’s–Embarrassment–which she sang but indifferently well. To Signor Tagliapietra we cannot award too much praise. He was in exquisite voice, and his singing was perfection itself. Mr. S. Liebling’s performance on the piano was artistic and finished.
At the conclusion or the first part of the concert the piano was closed, and two young men raised the “receiving” apparatus of the telephone and placed it on the piano, after which a wire was adjusted to it, thus establishing direct communication with the “sending” instrument, in the office of the Western Union Telegraph Company in Philadelphia, presided over by Mr. F. Boscovitz. A telegraph operator next appeared and took up his position at the little table above referred to. Immediately afterwards a tall, spare gentleman with a beard came forward. This was Professor Gray, the inventor of the telephone. The Professor declared that he did not desire to exhibit the telephone as a great musical instrument, and if anybody expected to listen to grand music, he would inform them in advance that they would be disappointed. The Professor, although doubtless a genius in some respects, cannot be said to number oratory among his gifts. In a rambling, disconnected and ungrammatical speech, out or which it was impossible for the life of us to make head or tail, the Professor endeavored to explain in a scientific manner many things connected with the telephone. He was not permitted to continue the infliction very long, for the audience grew impatient, and manifested their feelings in a quiet way. The Professor was not slow to take the hint, and concluded his introductory remarks by requesting the greatest silence. He then directed the telegraph operator to inform Mr. Boscovitz at Philadelphia that everything was in readiness and he might begin. Within three or four seconds the first notes of “Home, Sweet Home” were distinctly audible in every part of the spacious ball, the melody being recognized perfectly.
We can best describe the music of the telephone as heard last night by comparing it to the sound that would be produced slowly on an organ with one finger. The higher notes were rather feeble. The utmost stillness prevailed, and at the finish the applause was long and enthusiastic. The remaining selections on the programme were played in the order given, all with the same success, as follows:
1. “Home, Sweet Home.” 2. “Come Genil.”–Don Pasquale. 3. “Then You’ll Remember Me”–(Bohemian Girl.) 4. “The Last Rose of Summer.” 5. “M’Appari,” Romance–(Martha.) 6. “The Carnival of Venice.”
At the conclusion of the exhibition the judgment of all present was highly flattering to what may yet be numbered among the greatest inventions of modern times.