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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

Sound diffraction

Graphic:
Diffraction is a typical feature of sound waves when they meet an obstacle.

The diffraction of sound waves is a physical mechanism which ensures the entry of sound waves into acoustic shadows.
That means the sound is audible in areas which are cut off from the direct sound incidence, such as behind obstacles.

Information and ideas:
Diffraction of light can be proved when a parallel ray beam of monochrome light is directed at a narrow opening. A screen set up behind the opening gives us a diffraction figure (bright and dark stripes that lose intensity the further outwards they are). With sound, a direct reference to the students' everyday world is even easier: Why can you hear noise from a street in front of a building even when you are behind the building?
Further information about this graphic is provided as an information sheet on the media portal of the Siemens Stiftung.

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

Medientypen

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Lernalter

13-18

Schlüsselwörter

Chart Optics Sound Wave (physics)

Sprachen

Englisch

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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

Sound field and sound absorption

Schematic diagram:
Concentric propagation of sound waves. The lines of the same loudness are shown which decreases as the distance to the sound source increases.

Why do we hear less the further away we are from the source of sound?
Sound propagates from its source in a circular way, the sound energy spreads over an increasingly large area and the sound pressure decreases accordingly.
In a free sound field it decreases by about 6 dB every time the distance to source is doubled. Within a room, however, this only applies very close to the sound source.

Information and ideas:
Useful for discussing why we hear less the further away the sound source is.

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

Medientypen

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Lernalter

11-18

Schlüsselwörter

Chart Sound Wave (physics)

Sprachen

Englisch

Dieses Material ist Teil einer Sammlung

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Siemens Stiftung

Sound refraction

Schematic diagram:
Sound refraction in air with different temperature layers (from warm to cold).

The speed of sound in the air depends on the density and thus the temperature of the air: At high temperatures, the sound travels faster than it does at lower ones. So when sound moves from a warm layer of air to a colder one, its speed decreases.
However, the direction in which the sound spreads also changes as the speed changes. It is said that the sound wave is "broken?. In the case described, i.e. when sound moves from a warm to a cold layer of air, the sound wave is broken upwards.

Information and ideas:
How does sound behave when it moves from a colder to a warmer layer?
Is it correct that you hear worse against the wind than with the wind?
The latter can be checked together with students in an experiment.
A comparison with the refraction of light rays can be made.

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

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Siemens Stiftung

The Ear, Hearing and Hearing Impairment;: Vibrations and waves

Overview graphic:
Overview of the most important parameters of vibrations and waves.

Electromagnetic waves are vibrations in the electrical and magnetic field that propagate through space at the speed of light. The parameters of vibrations and waves, such as frequency, are presented in an overview.

Instructions and ideas:
As overview information for students on the topic of "vibrations and waves". Important basis for understanding sound waves in acoustics.

Medientypen

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Lernalter

11-18

Schlüsselwörter

Chart Optics Sound Wave (physics)

Sprachen

Englisch

Dieses Material ist Teil einer Sammlung

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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

Phase diagram of water

Diagram:
A P-T diagram for pure water. The lines indicate the temperature and the pressure at which the solid, liquid, and vapor phases exist in equilibrium. All three phases exist in equilibrium only at the triple point; otherwise, there are a maximum of two phases.

In addition to the equilibrium curves (melting pressure curve, sublimation curve, vapor pressure curve), the diagram also includes the pressure and temperature data for the melting, boiling, triple, and critical points.
Attention: The axes of the diagram are not shown true to scale.

Information and ideas:
This diagram also reflects the density anomaly of water (lower density in the solid state than in the liquid state): The melting pressure curve shows a negative slope. The reason for the density anomaly is the hydrogen bonds.

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Siemens Stiftung

Steam pressure curve and phase diagram of water

Charts:
The steam pressure curves (p-V diagram) and the phase diagram (p-T diagram) of water are compared.

If you heat water to 100 °C at normal atmospheric pressure, it turns into steam. But what effect does raising or lowering the pressure have on the vaporization temperature?
The answer to this is given by the steam pressure curve (T-curves in the p-V diagram on the left) and the phase diagram (p-T diagram of the right) of the water. Steam pressure is the term for the pressure at which gas and liquid are in equilibrium, i.e. the same number of molecules evaporate as condense back into water. Above the critical temperature (numerical values are given) the water is always gaseous, regardless at what temperature, and it can be treated as a real gas (Van der Waals equation, formula is given). At every temperature below the critical temperature there is a steam pressure for which there is a two-phase zone (liquid and gaseous). In the liquid phase range it is possible to recognize from the steep rise in the curves that liquid substances are barely compressible.
The critical temperature must not be confused with the triple point temperature (see p-T diagram). This characterizes the values of temperature and pressure at which all phases (solid, liquid and gaseous) are present simultaneously.

Information and ideas:
At what temperature does water boil on Mount Everest? So-called "Steam pressure tables" provide information about this. It would also be interesting to refer to the phase transition points as temperature critical points. At the phase transition from liquid to gaseous the energy applied does not initially lead to an increase in temperature. The same applies to the melting of ice. Not until all the water has evaporated or melted does the temperature rise further.

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Siemens Stiftung

;: Chemical energy

Chart:
Chemical energy as binding energy between atoms (as a potential curve in the illustration).

Chemical energy is present both in the bond between atoms and molecules as well as in the potential for chemical bonding. This energy can be released in the form of heat during the bonding process or when those bonds are broken. This "heat of reaction" is also referred to as reaction enthalpy (H). The release of heat (dH < 0) is referred to as an exothermic reaction. An endothermic reaction is when heat is absorbed (dH > 0).
Every mixture of source materials that can react to produce end products can be regarded as a potential source of chemical energy.
Microscopically speaking, this chemical energy can be found in the bonds between individual atoms, as illustrated in the potential curve.

Information and ideas:
Chemical energy is a form of energy that is easy to store - whether in the human body or in batteries. An additional example is hydrogen as a chemical energy store for renewable energy sources.