1925 __ « You need a headset »
‣ Comment : In telling us why we need a headset, Brandes offers a promising entry point into a much longer history of listening. Headsets were not actually necessary for tuning a radio. Instead, they helped their users to better “DX” or listen for distance. — to hear very faint, indistinct, and distant sounds, stretching the existing capacity of their radios and their ears. Picking up faint, faraway stations was one of the holy grails of amateur radio listening. Brandes’s ad is clearly aimed at DXing. As the ad also intimates, headphones isolate their users in a private world of sounds. They help create a private acoustic space by shutting out room noise and by keeping the radio sound out of the room. They also help separate the listener from other people in the room. Through this isolation, the headphones can intensify and localize listeners’ auditory fields, making it much easier to pay attention to minute sonic details and faint sounds. Brandes’s headphones provide the “truest and clearest reception” because of this empasis on sonic detail through isolation. (Jonathan Sterne, pp. 87-88) — Very sensitive headphones such as those manufactured by Brandes around 1919 were commonly used for early radio work. These early headphones used moving iron drivers, either single ended or balanced armature. The requirement for high sensitivity meant no damping was used, thus the sound quality was crude. They also had very poor comfort compared to modern types, usually having no padding and too often having excessive clamping force to the head. Their impedance varied; headphones used in telegraph and telephone work had an impedance of 75 ohms. Those used with early wireless radio had to be more sensitive and were made with more turns of finer wire; impedance of 1,000 to 2,000 ohms was common, which suited both crystal sets and triode receivers. In early powered radios, the headphone was part of the vacuum tube's plate circuit and had dangerous voltages on it. It was normally connected directly to the positive high voltage battery terminal, and the other battery terminal was securely earthed. The use of bare electrical connections meant that users could be shocked if they touched the bare headphone connections while adjusting an uncomfortable headset. (Compiled from various sources) — Matched-tone * is another exclusive Brandes feature. The receivers on each head-set are carefully selected by experts so that the sound produced in each receiver will be of exactly the same volume and of the same pitch. Although the work of matching these receivers in tone is costly, the result produced is well worth the effort. Maximum sensitivity of receivers cannot be had when the signals sound differently in each receiver. If one receiver was louder than the other, the signals would sound "mushy" and the user would unconsciously concentrate his attention on one receiver alone. As a result of this, the advantage of having two receivers would be lost. With the Brandes Matched-Tone * headset the sound produced in each receiver is of the same volume. The user does not experience the confusing sensation of listening to apparently two stations sending the same message. (In Beginner's Book of Radio, Frederick Dietrich, 1922, pages 18-26)
‣ Source : Sterne, Jonathan (2003), “The Audible Past - Cultural Origins of Sound Reproduction”, Durham & London : Duke University Press, pp. 87-88.
‣ Urls : http://earlyradiohistory.us/1922brn.htm (last visited )
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