A brief history of electroacoustics, pt. 6:
Various loudspeaker mechanisms

The invention of the telephone set off a wave of creativity, and almost all conceivable transducer mechanisms were tried out in the 1870s and 80s. Some of them developed into usable devices, others serve mainly as illustrations of man’s creativity. In this part, some of them will be presented, ranging from useful, mainstream designs to the downright bizarre.

Read more…A brief history of electroacoustics, pt. 6:
Various loudspeaker mechanisms

MAUS i media

I løpet av denne uka har vi vært i media med MAUS-prosjektet, som handler om auralisering av utendørs støy. En sak om prosjektet, skrevet av Åse Dragland, har blitt publisert tre steder på norsk:

Saken har også blitt oversatt og publisert i flere internasjonale medier. Du finner en liste nedenfor.

I tillegg har Erlend og Jakob vært i Norgesglasset på P1 og vist fram og snakket om verktøyet. Du kan høre klippet her, men raska på; klippet er bare tilgjengelig i seks måneder.

Read more…MAUS i media

A brief history of electroacoustics, pt. 5:
Moving coil loudspeakers of lasting impact

In Part 4, we looked at various early variants of moving coil (or moving conductor) loudspeakers, including predecessors of the modern moving coil cone driver. In this part I will present two specific designs that made a lasting impact on loudspeaker technology. One is a direct radiator; the other is a horn driver.

In the early part of the 1920s, many researchers were working on loudspeakers, based on various principles. E.C. Wente at the Western Electric Engineering Department (to become the Bell Telephone Laboratories) worked on a small direct radiating moving coil loudspeaker that was later patented (US patent 1812389, filed April 1, 1925 and granted the same date 1935). In England, Paul Gustavus Adolphus Helmuth Voigt at Edison Bell also worked on moving coil loudspeakers and microphones. In May 1924, he applied for a patent on a moving coil loudspeaker, but unfortunately a little to late. He was beaten at the finish line by two engineers at the General Electric Company, C.W. Rice and E.W. Kellogg.

Read more…A brief history of electroacoustics, pt. 5:
Moving coil loudspeakers of lasting impact

A brief history of electroacoustics, pt. 4:
Early moving coil loudspeakers

The moving coil loudspeaker is without doubt the most common electroacoustic transducer in use. It consists of a circular coil suspended to move freely in a radial magnetic field. This transducer principle was first described by Ernst W. Siemens in his 1874 patent. He describes his transducer as a means for “obtaining the mechanical movement of an electrical coil from electrical currents transmitted through it.” He also mentions that the coil could be used to move visible or audible signals, but he had obviously nothing more elaborate in mind than a bell or buzzer.

Read more…A brief history of electroacoustics, pt. 4:
Early moving coil loudspeakers

A brief history of electroacoustics, pt. 3:
Microphones

In the preceding parts, I have mentioned several microphone (transmitters, in telephone lingo) types that were used in early telephone experiments. The first type, the one described by Borseul, was a make-and-break type transmitter, which was used by Reis. This type of transmitter is not very useful, and can hardly transmit understandable speech. The very closely related loose-contact transmitter, is the basis for the carbon microphone. Also related is the variable resistance transmitter used by Elisha Gray in his bid for the telephone. A needle was attached to the transmitter diaphragm, and the other end of the needle touched the surface of a conductive liquid in a conductive cup. When the diaphragm vibrated, the needle made more or less area in contact with the liquid, and the resistance of the circuit varied.

Read more…A brief history of electroacoustics, pt. 3:
Microphones

A brief history of electroacoustics, pt. 2:
The telephone

Two inventors with significantly improved, successful telephone devices made it to the patent office on the same day, February 14, 1876. These two inventors were Elisha Gray (1835-1901) and Alexander Graham Bell (1847-1922).

Read more…A brief history of electroacoustics, pt. 2:
The telephone

A brief history of electroacoustics, pt. 1:
The birth of electroacoustics and early telephones

While electroacoustics is as old as lightning and thunder, man’s controlled application of it dates back to the 18th century. Early electroacoustic phenomena were mere replicas of the natural occurring ones; the crackles of electrostatic discharges in the early experiments in electricity. In 1729, it was discovered that some materials conducted electricity, and the idea that this could be used to transmit intelligence was born.

Read more…A brief history of electroacoustics, pt. 1:
The birth of electroacoustics and early telephones

– Det burde innføres strengere restriksjoner på lydnivået på festivaler i Norge

SINTEF-forsker Tron Vedul Tronstad er intervjuet på nrk.no om hørselsskader som følge av høy konsertlyd, blant annet på festivaler. I prosjektet NEXT STEP, finansiert av Norges Forskningsråd, undersøker SINTEF hvordan midlertidige hørselsskader oppstår, og hvordan varige hørselsskader kan oppdages før de har utviklet seg for langt.

Read more…– Det burde innføres strengere restriksjoner på lydnivået på festivaler i Norge

Hvordan snakke i telefonen?

Du trenger kanskje ikke å rope? ARCs professor Peter Svensson ved NTNU har nylig blitt intervjuet av Dinside om hvorfor folk roper i telefonen likevel. Kjernen er Lombard-effekten, altså at du naturlig justerer stemmenivået og stemmeleiet ditt etter støyen rundt deg og stemmenivået til samtalepartneren din. Det kan derfor altså være lurt å redusere både ditt eget stemmenivå og avspillingsnivået i telefonen din.

Du kan lese hele intervjuet hos Dinside. (Øh…du kan også gjerne se bort fra overskriften.)

Bildet er hentet fra Wikimedia Commons

Akustisk lokalisering av fly med mikrofonklynger

I området rundt flyplasser er det ofte satt opp ulike måleanlegg og spesielt kan dette være anlegg for å overvåke støy fra aktiviteten på flyplassen. I noen tilfeller er det satt opp mikrofonklynger som i tillegg kan fokusere på støyen fra enkeltfly og også beregne flyenes posisjon. En kort forklaring av prinsippet bak dette er gitt under, og en mer detaljert teknisk beskrivelse finnes i en artikkel publisert i tidskriftet Acta Acustica nå nylig. Dette er beskrevet lenger ned.

Read more…Akustisk lokalisering av fly med mikrofonklynger