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Siemens Stiftung

The Ear, Hearing and Hearing Impairment; Teaching unit: From the drum to the eardrum: Resonance body piano

Photo:
Grand piano and piano are good examples of the great significance of resonance bodies with regard to volume and sound.

The frame and the air in the piano vibrate in resonance with the string that has just been struck. Whereas the more modern grand piano "fills" whole concert halls, its historical predecessor, the spinet, is just loud enough for the living-room. Apart from the volume the tone colour of the spinet is also much thinner. This comparison makes the importance of the resonance body very clear - both generally in the production of sound and specifically in music.

Information and ideas:
A practical example from the field of music shows how important the subjects of Physics and Acoustics are for the world of art and communication.

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

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Siemens Stiftung

Frequency differentiation in the uncurled cochlea

Labeled graphic:
High-pitched tones are heard in the front part of the cochlea, low tones are heard in the back part.

As the sense of hearing is able to differentiate locations of the nerves, it is able to recognize the frequencies.

Information and ideas:
This graphic is good for creating a link between the topics of "Sound? and "Hearing?.
Further information regarding this graphic is available as information sheet on the media portal of the Siemens Stiftung.

Relevant for teaching:
Perception of sound
Human hearing ability
Communication and understanding
The human body
Structure and functions of a sensory organ

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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

The Ear, Hearing and Hearing Impairment: Sound curve vs. frequency and amplitude

Chart:
Shows vibration with a high and loud tone.

With respect to the sound curve upper left, the lower left sound curve has twice the sound pressure (amplitude is twice as high). The upper right curve, however, has twice as high tone (twice the frequency). Bottom right, both the amplitude and frequency have been doubled.The following can be said about a sound curve:
- Amplitude stands for volume.
- The frequency indicates the pitch.

With high tones, the wave shapes are narrow and are repeated quickly, with low tones, the wave shapes are broader and are repeated more slowly.

Information and ideas:
Connection can be made to the curve discussion in Mathematics. To be used on worksheets, transparencies etc.

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

Medientypen

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Lernalter

11-18

Schlüsselwörter

Sound Wave (physics)

Sprachen

Englisch

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Siemens Stiftung

Test tone as purest sound signal

Graphic:
Oscilloscope graph of a periodic tone of a single frequency (pure tone). Produced with an electronic sound generator.

Simple periodic tones consist of a "pure tone" with a single frequency (mono-frequency sine tone). That only exists in measuring technology as a synthetically generated "test tone".

Information and ideas:
Possible cross reference: Examination of aperiodic speech signals with the help of spectral analysis.
Further information on this graphic is available as information sheet on the media portal of the Siemens Stiftung.

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

Medientypen

Bild

Lernalter

11-18

Schlüsselwörter

Sound Wave (physics)

Sprachen

Englisch

Dieses Material ist Teil einer Sammlung

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Siemens Stiftung

Bang as aperiodic sound impulse

Graphic:
Oscilloscope graph of a bang as example of an aperiodic tone of high volume and short duration (impulse).

Basically, a bang is an abrupt, mechanical, aperiodic oscillation of very short duration and large amplitude. The amplitude also decays quickly.
Examples are a gunshot, bursting of a paper bag or a door slamming shut.

Information and ideas:
Possible cross reference: Examination of aperiodic speech signals with the help of spectral analysis.
Further information on this graphic is available as 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

11-18

Schlüsselwörter

Sound

Sprachen

Englisch

Dieses Material ist Teil einer Sammlung

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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

Bild

Lernalter

11-18

Schlüsselwörter

Chart Sound Wave (physics)

Sprachen

Englisch

Dieses Material ist Teil einer Sammlung

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Siemens Stiftung

Sound propagation: tambourine & candle 3

Photo:
The sound waves from the tambourine blow out the lit candle. Third picture of three of the experiment: "Tambourine blows out candle".

The experiment "tambourine blows out candle" demonstrates clearly how sound waves propagate and that a movement of air particles is associated with it.

Information and ideas:
Experiment which can be done easily in class.
Further information regarding this photo is available as information sheet on the media portal of the Siemens Stiftung.

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


Dieses Material ist Teil einer Sammlung

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Siemens Stiftung

Tuning fork as "simple" sound

Graphic:
Oscilloscope graph of a tuning fork tone as example of a simple tone with visible upper harmonics in the starting phase of oscillation.

Tuning forks as well produce simple periodic tones but, strictly speaking, they are not really pure as there are several upper harmonics already overlapped.

Information and ideas:
Possible cross reference: Examination of aperiodic speech signals with the help of spectral analysis.
Further information on this graphic is available as information sheet on the media portal of the Siemens Stiftung.

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

Medientypen

Bild

Lernalter

11-18

Schlüsselwörter

Sound Wave (physics)

Sprachen

Englisch

Dieses Material ist Teil einer Sammlung

Bild

Siemens Stiftung

Sound propagation: tambourine & candle 1

Photo:
Tambourine in front of a lit candle. First of three pictures of the experiment "tambourine blows out candle".

The experiment "tambourine blows out candle" demonstrates clearly how sound waves propagate and that a movement of air particles is associated with it.

Information and ideas:
Simple experiment that is easy to do in the classroom.
Further information regarding this photo is available as information sheet on the media portal of the Siemens Stiftung.

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


Dieses Material ist Teil einer Sammlung