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Siemens Stiftung

The Ear, Hearing and Hearing Impairment: Refraction

Graphic:
The wave front model of refraction on an interface makes it clear why the direction of the sound propagation changes.

When waves cross over from one medium to another, the speed at which the waves spread changes. Consequently, the wave normals of the incident and broken waves have different directions. With light waves, the change in the index of refraction at the boundary is the cause; with sound waves, it is the change in the density.
The graphic illustrates the case when the speed of propagation becomes slower at the transition from the first to the second medium: The wave is broken at the perpendicular of the boundary surface.
An explanation of this phenomenon is provided by the Huygens' Principle: Every point on a wave front is the starting point for a new wave, known as an "elementary wave". The enclosing end of the elementary wave creates the new wave front.

Information and ideas:
Refraction at boundaries also occurs with sound waves (for example, in the atmosphere at the transition from warm to cold layers of air).

Relevant for teaching:
Sound/acoustics: parameters
Vibrations and waves

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Siemens Stiftung

The Ear, Hearing and Hearing Impairment: Diffraction

Graphic:
Diffraction of waves on encountering an obstacle.

The graphic shows possible diffraction effects according to aperture and wave length.

Information and ideas:
Diffraction arises in sound waves as well, for example at corners of buildings.
Further information regarding this graphic is available as information sheet on the media portal of the Siemens Stiftung.

Relevant for teaching:
Sound/acoustics: parameters
Vibrations and waves

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Siemens Stiftung

Speech signal - individual word

Chart:
Screenshot of the oscillographic curve of the spoken word "dogs".

Speech sounds are fluctuating sound signals where the composition of frequencies changes all the time.
Aperiodical overlap periodical parts. Unlike noises, some of which have similar frequency curves, sound in speech is always the carrier of meaning or of messages sent out by the speaker. Other noises like smacking of lips, hissing, rhythms, basic pitch are typical of the individual (acoustic fingerprint) but not essential for the speech content!

Information and ideas:
Supplementary to worksheets and transparencies.

Relevant for teaching:
Sound/acoustics: parameters
Vibrations and waves
Communication and understanding

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Siemens Stiftung

The Ear, Hearing and Hearing Impairment: Speech as highly complex sound signal

Graphic:
Oscillographic curve of the spoken sentence "It's raining cats and dogs".

Speech sounds are fluctuating sound signals where the composition of frequencies changes all the time.
Aperiodical overlap periodical parts. Unlike noises, some of which have similar frequency curves, sound in speech is always the carrier of meaning or of messages sent out by the speaker. Other noises like smacking of lips, hissing, rhythms, basic pitch are typical of the individual (acoustic fingerprint) but not essential for the speech content!

Information and ideas:
Supplementary to worksheets and transparencies.

Relevant for teaching:
Sound/acoustics: parameters
Vibrations and waves
Communication and understanding

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Siemens Stiftung

Auditory path - brain parts hearing

Labeled graphic:
"Auditory pathway? describes route taken by auditory nerve impulses in and through the brain. But the hearing process is not over yet.

The auditory pathway is the nerve tract for the sensation of hearing.
People used to think that the senses were more localised. Now we know that apart from the auditory pathway, lots of other parts of the brain are involved, too - parts that are also used by the other senses. It is this that makes it possible for human intelligence to understand abstract concepts beyond the mere recognition of patterns. To be able to understand the complex facts of a complex sentence does, after all, involves more than recognizing the words together.

Information and ideas:
Further information regarding this graphic is available as information sheet on the media portal of the Siemens Stiftung.

Relevant for teaching:
Reception and processing of information
Perception, recognition, action

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Siemens Stiftung

Speech recognition sentence - syllable - phoneme

Chart:
The components of speech, from phoneme to sentence presented visually.

The graphic shows the oscilloscope curve of the spoken sentence "It?s raining cats and dogs" and excerpts from the units from which speech is composed: sentence, word, phoneme.

Information and ideas:
Speech recognition and speech synthesis are very topical themes in the field of information and communication technology.
Further information on this graphic is available as information sheet on the media portal of the Siemens Stiftung.

Relevant for teaching:
The human body
Structure and function of a sense organ
Reception of impulses and information transmission
Sensory perception

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Siemens Stiftung

How long will our energy sources last?

Chart:
A bar chart shows an overview of the remaining years of use of primary energy sources.

Of the fossil energy sources, petroleum will be the first to run out. What is the situation for the other fossil energy sources? Can new technologies delay the point in time when they run out? And is it really true that renewable energy sources never run out?
The time axis has a logarithmic scale.

Information and ideas:
Students learn that the logarithmic scale represents numbers ranging over several powers. More in-depth information regarding how long energy sources will last is provided in the "An overview of energy sources? information sheet.


Dieses Material ist Teil einer Sammlung

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Siemens Stiftung

Communication costs energy

Interactive graphic:
Overview of the annual energy requirement of communication with a smartphone

In modern communications, as with every form of communication, a message is sent from a transmitter via a channel to a receiver. A smartphone is used daily, to communicate, navigate via GPS, or call up information from the Web. In this context, the graphic shows devices and transmitters with their annual energy requirement in kilowatt-hours (kWh). Most users have little idea about the amounts of energy (particularly electric power) that are needed for this modern communications technology. Servers, for example, need energy for uninterrupted operation and for the required cooling of equipment.

Information and ideas:
This topic raises questions such as: How much energy is needed worldwide for mobile radio communications? What could this energy otherwise be used for?


Dieses Material ist Teil einer Sammlung

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Siemens Stiftung

The Ear, Hearing and Hearing Impairment: Effects of noise

Schematic diagram:
The graphic shows that - apart from physical effects - sound does not become noise until it reaches the brain.

Noise has effects on the physical and mental health of human beings. What the individual subjectively considers to be noise depends on a number of factors, for example the individual's own mood.

Information and ideas:
Can be used as introduction to topic "What are the effects of noise??.
Can also be used for illustration purposes: individual parts can be covered up (and then gradually uncovered in the course of the lesson).

Relevant for teaching:
Noise: causes, effect, protection

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Siemens Stiftung

Normal audiometric audibility limit

Chart:
Audiometric audibility limit of a person with normal hearing with typical frequency and loudness ranges for speech and music.

The speech range is that range of frequency and loudness where speech communication usually takes place. Within the audiometric audibility limit it is the kidney-shaped range. In our diagram it is coloured blue.

Information and ideas:
An attempt at comparing diagrams showing normal hearing and reduced hearing can be done by students individually - as homework. It is useful for testing written expression (English) as well as for testing basic skills from Mathematics or Physics (how to interpret a diagram, for example).

Relevant for teaching:
Hearing defects/hearing impairment
How hearing functions
Sound/acoustics