Project: Next Step

Project: Next Step

Noise induced hearing loss (NIHL) is one of the most common occupational diseases. This is a fact even if most countries have legislations specifying how much sound employees can be exposed to. Therefore new models for NIHL seem to be necessary to reduce the risk of developing hearing disorders.

In the Norwegian petroleum industry much attention has been paid to occupational noise and hearing damage in the last decade. Statoil ASA has, in collaboration with Honeywell, been involved in several projects at SINTEF with this in mind. The current ongoing project is called Next Step (Noise Exposure Tackled Safely Through Ear Protection).

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A brief history of electroacoustics, pt. 9:
Horns: Cinema sound and large scale sound reproduction

A brief history of electroacoustics, pt. 9: Horns: Cinema sound and large scale sound reproduction

The 1920s saw much development in horn loudspeakers, and loudspeaker in general. Western Electric already had their microphones, amplifiers, straight exponential horns, and very good balanced armature transducers. At this time, much research was also put into disc recording and reproduction at the Western Electric Engineering Department, and simultaneously, optical recording of sound was also in progress, using Wente’s Light Valve. The time seemed ripe to attempt sound film. The story has been told elsewhere, but in short, most of the industry turned down Western Electric’s offer. They “knew” sound film would not work. But the Warner Bros found in the WE system something that could help them beat the big guys in the industry, and after the success of their first sound film, the rest is history.

Read more…A brief history of electroacoustics, pt. 9:
Horns: Cinema sound and large scale sound reproduction

A brief history of electroacoustics, pt. 8:
Horns: Early development

A brief history of electroacoustics, pt. 8: Horns: Early development

It is hard to tell when horns first were used. They have been in use for thousands of years as instruments, and man must early have discovered the amplifying effect of a pair of cupped hands in front of his mouth, or behind his ears. Ear trumpets were early implementations of this, and the first hearing aids.

Horns were used on phonographs and gramophones from the start. This was the only way to get the required volume from the tiny motions of the needle. The theoretical understanding of horns was still small though, and most of the work was experimental. Early models used conical horns, but as theory progressed, the superiority of the exponential horn was recognized.

Read more…A brief history of electroacoustics, pt. 8:
Horns: Early development

Tolerance for aircraft noise remains unchanged

Tolerance for aircraft noise remains unchanged

The annoyance response of different communities to aircraft noise has always been difficult to predict. However, in recent years, many studies report extremely high levels of annoyance for the given noise exposure levels. This has led to the belief that people are nowadays less tolerant to aircraft noise than they were a few decades ago.

We’ve looked at the results of 57 aircraft noise surveys conducted between 1961 and 2015, and found that people’s tolerance to aircraft noise hasn’t changed at all.

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Invitation to the 39th Scandinavian Symposium on Physical Acoustics

Invitation to the 39th Scandinavian Symposium on Physical Acoustics

The 39th Scandinavian Symposium on Physical Acoustics will be held at Geilo Hotel from January 31 to February 3, 2016. This year it is organised by Ulf Kristiansen and Erlend Viggen, both at ARC. The theme for the meeting will as usual be physical acoustics, with emphasis on hydroacoustics, nonlinear acoustics, ultrasound, general sound propagation and applications in technology, medicine and fisheries.

The purpose of these meetings is primarily to stimulate contacts and exchange information between different Scandinavian teams working in this research area. Although the symposium is Scandinavian, foreign participants are most welcome, and the meeting language will be English. As usual, we expect a rather informal tone, the main goal being to create contacts, not only during sessions, but also by social activities, indoors and outdoors (cross country and downhill skiing). The meeting normally attracts about 50 participants holding about 25 talks throughout 5 sessions.

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A brief history of electroacoustics, pt. 7:
Loudspeaker enclosures

A brief history of electroacoustics, pt. 7: Loudspeaker enclosures

Reis’ telephone was perhaps the first loudspeaker of any kind, as it employed a magnetostriction driver mounted in a resonating box. But it would still take many years before inventors discovered the virtues of baffles and enclosures. As Hunt puts it, the baffle is probably the most frequently rediscovered feature of loudspeaker art. Stokes, in 1868, pointed out that the radiation efficiency could be improved by preventing air circulation around the edges of a vibrating surface (the acoustic short-circuit). Rayleigh, a few years later, gave the now classic analysis of the radiation from a piston in an infinite baffle. But by the time loudspeakers were being produced in great numbers, Rayleigh’s Theory of Sound had been out of print for more than two decades, and many inventors discovered the baffle before they discovered Rayleigh.

Read more…A brief history of electroacoustics, pt. 7:
Loudspeaker enclosures

Predicting aircraft noise annoyance

Predicting aircraft noise annoyance

Noise is, by its very definition, annoying. Intuitively, lots of noise is more annoying than noise that is barely audible. Therefore, the concept of “tolerance” is important: Given the noise situation, can we predict people’s annoyance with this noise?

To answer this question, we first need ways to quantify both annoyance and noise. Annoyance is an emotion, but that does not mean it is not measurable. Researchers have developed very specific questions and answer scales that allow for international comparison of people’s annoyance with specific types of noise.

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

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

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

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

How do you imitate the sound of traffic?

How do you imitate the sound of traffic?

We previously wrote about the MAUS project, where we are building an auralisation tool to simulate the sound from virtual noise sources outdoors in order to give a realistic representation of how a future noise source will sound when it has been developed. One such noise source that we have been working on is traffic, one of the biggest issues in environmental acoustics. But how do you simulate the sound of traffic on a computer?

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