More Than Meets the Ear: The Invention of the Loudspeaker
- Tuesday, November 08, 2011
Sometimes we scratch our heads looking for ideas for this column. At other times, topics stare us right in the face that we fail to recognize! Ray helps run the sound system at our church, a job which is getting increasingly complicated with a growing choir, an orchestra, soloists, special music, visiting groups, and recording sessions.He and the others who service the music ministry are constantlyadjusting and fine-tuning the audio system to best fit the needs of the church. And within that complex job lies the topic for this month’s column.
While there are many important parts to the system, it would make no sense to have all of that equipment without loudspeakers to project the music to the congregation—and loudspeakers are used in many other ways that you may not have thought about. Most people take loudspeakers for granted, but there is more to them than meets the ear!
The World Before the Loudspeaker
Lots of archaeological sites once served as theaters for people to watch plays, listen to concerts, or attend other public events. The earliest sites were constructed in a shape called an “amphitheater.” An amphitheater is an open-air venue where the audience sits on an arrangement of seats that curve slightly less than a semicircle, facing a stage area where the event of interest takes place. Some ancient amphitheaters could seat several thousand patrons, each wanting to see and hear what was taking place.
The problem was that there were no sound systems or loudspeakers to project the sound to the audience. In a testament to ingenuity, amphitheater designers knew that sound would be a problem, so they devised a way to mechanically control the projection of sound toward the audience. How did they do it? Some of you may have experienced a similar situation if you have ever had the chance to use a “whispering wall.” A whispering wall, or a “whispering gallery” as it is sometimes called, is a curved stone wall that seems to amplify your whispered voice so another person can hear it. The trick is that when you whisper, the solid wall projects your voice around the curve to a second person who has his ear near the wall. The wall is not really amplifying (or increasing the intensity of sound)—it’s just controlling the direction of your voice, often while suppressing any outside noises. It helps you hear more clearly.
Early sound engineers designed curved surfaces behind the amphitheater stage that served to channel the sound toward the seating area. Instead of transmitting the sound along a wall, the curved surface was used to focus the sound toward the audience. Pretty clever! If you recall from our article in the Nov/Dec issue of Home School Enrichment, a piano’s soundboard works in a similar manner: it projects the relatively quiet sound of the string vibrations out to the audience.
The early 1600s ushered in Shakespearean plays performed in the Globe Theater. No one knows the exact details of the Globe Theater’s construction, but it was thought to hold over 1,000 people. Like the ancient amphitheaters, it was an open-air configuration with no elaborate sound systems. The performers were instructed to “bellow” out their lines in low voices so they could be heard by the audience. Low sounds project much better than high-pitched sounds. That is why you can hear the rumbling of thunder a long distance from a storm.
A new way to amplify and project sound was needed, but the technology to do so did not exist. People invented many variations of a device we know as a megaphone. Modern megaphones are electrically powered systems, but early megaphones were simply hollow, cone-shaped horns used to project a person’s voice in a specific direction, much like the megaphones that cheerleaders use at football games. Although simple, these work reasonably well. These horns took on many variations, the names of which can give us clues as to what they were used for: the speaking-trumpet, the fireman’s horn, the bullhorn, the blowhorn, and the loud hailer.
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