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Analog Sound Recording and Reproduction
During the acoustic recording period, the only scientist who early on worked with the type of horn that was used for commercial recording was Dayton C. Miller (1916) at the Case Institute of Technology in Cleveland, OH. He did not analyze horn performance mathematically nor did he work in recording onto a grooved medium, but he established calibration curves when he used conical horns for measur- ing waveforms from musical instruments by means of his phonodeik. Miller was a consultant to one of the recording companies, Aeolian-Vocalion, quite late in the acoustic pe- riod. Figure 4 shows a collection of phonographs of different manufacture in Miller’s laboratory in front of his phonodeik.
Scientific work on the directionality of conical horns, which would have helped in placing the instruments around the recording horn, did not appear until the 1930s (Hall, 1932; Goldman, 1934), too late to make any impact on acoustic recording practices, which had been almost universally ab- doned from 1926.
Figure 4. Dayton C. Miller was a consultant to Aeolian-Vocalion, a pho- nograph manufacturer. The photo shows the many types of phonographs that Miller measured and compared. On the brick pedestal (right front) is his calibrated Phonodeik with its conical horn. Photo ca. 1915. Courtesy of Arthur H. Benade, Case Western Reserve University, 1985.
Early Experiments in
Electromechanical Recording and Gradual De Facto Standardization
As the amplifying electronic tube became more common, the idea arose that microphones already known from tele- phones could be used to collect the sound. At the same time, it was realized that electromagnetic actuation could be used to vibrate the cutting stylus for disc phonograph purposes. The principle had already been used around 1900 for cylin- der phonographs, using, in effect, a simple telephone circuit
Figure 5. A cylinder phonograph with electrical reproduction, 1908. The stylus of the reproducer acts on a carbon granule microphone as used for telephones, and with an electric battery in series, the tele- phone headset reproduces the sounds from the cylinder through the funnel. From Max Kohl A. G. Chemnitz, Germany, Catalogue No. 50, Appareils de Physique, Tôme III, ca. 1920, p. 1055.
with a carbon granule microphone, battery, and phone re- ceiver with a cutting stylus mounted on its diaphragm. A cylinder phonograph reproducing electrically for demon- stration purposes is shown in Figure 5.
Various approaches were tried, but the surviving system was developed at the Bell Telephone Laboratories in connec- tion with their long-term research into speech transmission and line amplifiers. Maxfield and Harrison (1926) from Bell Laboratories published their design and made very effective use of equivalent circuit diagrams for the electromechani- cal transducers involved in cutting a record (F. V. Hunt in 1954 considered that this particular use was the very first large-scale application of these principles). At the same time, Maxfield and Harrison also developed the best purely acoustic reproduction system with close control of the mass- es, elasticities, and cavity volumes as well as the horn. If we compare Figures 4 and 6, we can see that outwardly there was not much difference in appearance between the “old” phonographs with an enclosed horn and the new construc- tion 10 years later. However, the performance had been im- proved remarkably.
By this time, the disc record with lateral modulation had be- come a de facto standard product, which was playable on any disc phonograph.
16 | Acoustics Today | Fall 2016