10.3 The decibel as a measure of sound amplitude

As I mentioned earlier, because a decibel is a way of expressing a ratio, it cannot by itself express the absolute size of anything. To express absolute values it must be referred to a fixed reference quantity, against which whatever is being measured can be compared. In the context of acoustics the reference used is the lower limit of audibility – the threshold of audibility. This varies from person to person, but has a nominal value that can be expressed as a pressure wave with an
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10.1 Introduction

For a variety of reasons, not least the very wide dynamic range of human hearing, the decibel (symbol dB) is often used as a unit for the amplitude of sound waves. The decibel is also used in other contexts, such as specifying the amplification of amplifiers or the degree to which a signal is affected by noise. In the context of sound, the use of the decibel as a unit captures something of the subjective impression of the way loudness changes with amplitude.

The decibel unit has
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7.1 The subjective experience

Two of the properties of sound that we have examined from an objective stance, frequency and amplitude, have a fundamental importance to our appreciation of sound and music. In this section I want to look more closely at the subjective interpretation of these two properties of sound. I should stress that I am talking about sine-wave sounds in this section. The complex, non-sinusoidal sounds encountered in music add extra layers of complexity to the relationships I am discussing here.

Ke
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4.6 Appreciating some implications for practice

I think for most people, the CSA case study would be experienced as a complex situation. If so this would be a good example of perceived complexity. Remember though, if you engaged with it as if it were a difficulty, just as the government minister did in Activity 42, you would not d
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2.5 Review

The title of this unit could have been Juggling with complexity: searching for system. This title seemed to capture something essential about the unit. Juggling is a rich metaphor and will be used explicitly in Part 3. But it also carries the idea of a skill that needs to be practised and that might seem incredibly awkward to begin with. You may find this idea helpful as you review your work in Part 1. Juggling is also a skill that, once practised, becomes second nature. This too may b
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References

Basalla, G. (1988) The Evolution of Technology, Cambridge, Cambridge University Press.
Baylis, T. (2000) Clock This: My Life as an Inventor, London, Headline.
Bell, D. (1988) ‘The third technological revolution and its possible socio-economic consequences’ (third annual faculty lecture), Salford, University of Salford.
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18.2.6 Encouraging diffusion

In general, innovations that are perceived as having relative advantages, being more compatible, less complex, observable, and trialable will diffuse more rapidly than other innovations.


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9 Part 2: Invention

Having taken a broad look at the whole innovation process from invention to diffusion, I'll go back and look more closely at what motivates individuals and organisations to invent. Then I'll consider how people generate ideas for inventions and the designs based on the inventions.


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6.2 Are cylinder ships a dead-end invention?

In 1924 Anton Flettner, a German physicist, tested a prototype of one of his inventions, a rotor ship. An expert in hydrodynamics and aerodynamics, Flettner had already experimented with metal sails, which he found increased sailing ship efficiency by 50 per cent. Next he moved on to an ingenious application of the Magnus effect – the idea that a sphere or cylinder spinning in an airstream develops a force at right angles to the moving air. This theory was developed to account for inaccurac
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9.1 User trip

This section introduces a simple method of investigating product use. Even such simple methods can provide useful information to guide product redesign and new product development.

The essential idea of user trips is simple: you just take a ‘trip’ through the whole process of using a particular product or system, making yourself a critical observant user.

The only way to learn how to make these user trips is to try one or two for yourself. You will be surprised how much you fi
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4.1 What it means to be good at managing

What does it mean to be ‘good at managing’ and what part does systems thinking and practice play? One way to explore the first question is to ask what you know about your work that a school leaver, or someone fresh from university, would not know. Consider a senior secretary, for example, someone who clearly has a fair amount of managing to do, in our terms. Such a person must have certain basic skills and knowledge (in word-processing, filing, etc.) the foundation of which will have been
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1.1.2 Egyptian calculation

Box 1 A note on Egyptian scripts and numerals

The earliest Egyptian script was hieroglyphic, used from before 3000 BC until the early centuries AD. Initially an all-purpose script, it was eventually used only for monumental stone-carving and formal inscriptions. It had been superseded (by abou
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4.4 Political implications

In chapter VI of A Practical View Wilberforce broadens his perspective from the primarily spiritual emphasis of the earlier chapters to a consideration of the political implications of his analysis. In so doing he contributed to the ongoing debate on the French Revolution and the changing nature of British society and politics.

A Practical View can usefully be compared here with another work that gave considerable prominence to religion in the aftermath of 1789, Edmund Bu
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5.4 Assessing Hume's views

The main value of Hume's essay lies in its discussion of our duties to God. Here Hume's arguments initially seem quite convincing. But arguments almost always seem convincing when they are first heard and understood. The real test comes when we try to think of possible objections. Here is one such objection, based on what has become known as the problem of evil, the problem of reconciling God's benevolence and omnipotence with the fact that evil exists in the world:

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4.5 The sans-culotte as revolutionary hero

Revolutionary symbolism (which we noted earlier with reference to the Declaration of the Rights of Man) extended to clothing: the wearing of the tricolour cockade was made compulsory for men by a decree of July 1792. The red ‘cap of liberty’ became the normal headgear of the sans-culottes, now officially idealized as heroes of the people.

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1.4 The economics of maintaining a heritage site

The National Trust operates within a complex web of funding. This comes from annual membership fees and from visitor receipts at individual sites. Each National Trust property is responsible for raising the income necessary to fund its own conservation activities and further development (although a large minority of sites cannot cover their costs). Properties raise this income through visitors charges and from catering, shop sales, etc. Failure to raise sufficient income can lead to job losse
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1.1 Background

Aberdulais Falls is under the control of the National Trust. It is set in an area of outstanding natural beauty that has attracted artists for centuries (Turner visited the ten-metre high waterfall in 1796). Aberdulais Falls also has a four-hundred-year history of industrial use, due to the opportunities it provides for water power. The industrial history of Aberdulais Falls goes back to 1584, when the availability of water power and fuel led to copper ore from Cornwall being smelted there. C
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3.1 Three interpretative methods

If the work of art has an existence beyond that of its maker, what are the limits of interpretation? This is a huge question, and possible limits and methods of interpretation are continually being propounded within the discipline. Helen Langdon chose to set Caravaggio's art within his life, with all the associations connected to the artist's biography. This unit will look at ways in which the work of art can be interpreted within and outwith references to the artist who created that work.
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4.5 Two mythological songs: ‘Prometheus’ (1819) and ‘Ganymed’ (1817)

Goethe's poem ‘Heidenröslein’, with which we began, is a mock folksong; ‘Erlkönig’ is a mock ballad along the lines of Scottish models. They are, so to speak, poems in fancy dress. ‘Prometheus’ and ‘Ganymed’ are songs on subjects from ancient Greek myth, but they are in no way imitations of ancient classical models. In these two poems Goethe has taken myths and created modern meditations on them of startling, but quite distinct, kinds.


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