Bild

Siemens Stiftung

The watering can as a trumpet

Photo:
Child blows into a watering can, thus producing relatively loud trumpet-like sounds.

By pressing the current of air between its lips, the child produces the original vibration. In addition, the entire air volume in the watering can is stimulated to start vibrating. The sound gets louder. At certain pitches, the watering can volume vibrates more or less. As in our case it is the lower pitched tones that tend to vibrate, the watering can trumpet produces a relatively muffled sound.

Information and ideas:
Easy experiment to do in class. Then comparisons can be made to various different musical instruments which work on this very principle.

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

Medientypen

Bild

Lernalter

6-18

Schlüsselwörter

Sound

Sprachen

Englisch

Bild

Siemens Stiftung

Sound reflection

Graphic:
When sound waves hit an obstacle, they can be reflected in a similar way to light.

When a sound wave hits a large, hard surface, sound reflection occurs:
Sound is reflected by the surface just as light is reflected by a mirror.

Information and ideas:
Reference to students' everyday world: Echo in the mountains.
Can be checked with the students in an experiment.

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

Medientypen

Bild

Lernalter

11-18

Schlüsselwörter

Sound Wave (physics)

Sprachen

Englisch

Bild

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

Bild

Lernalter

13-18

Schlüsselwörter

Chart Optics Sound Wave (physics)

Sprachen

Englisch

Bild

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

Bild

Siemens Stiftung

Sound propagation in solid bodies

Photo:
Demonstration of a simple experiment on sound propagation in solid bodies. A table top transmits sound, for example.

In old Westerns the Indians put their ears to the ground and listen and the bandits do the same at the railway line. The students can do the same at the table.
These examples show that not only air conducts sound but also solid bodies and how sound propagation is affected positively or negatively by different materials

Information and ideas:
Variations of the experiment:
A tuning fork that has been struck is put onto the table top. Now, put different materials between the tuning fork and the table top and observe the influence of these materials. In this way, the transmission of sound with different materials can be compared.
Use an alarm clock instead of the tuning fork. If you position your ear on the table top the alarm clock seems to be louder. How does the sound volume change if a plate or the like is positioned under the alarm clock?

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

Medientypen

Bild

Lernalter

6-18

Schlüsselwörter

Sound

Sprachen

Englisch

Dieses Material ist Teil einer Sammlung

Bild

Siemens Stiftung

The Ear, Hearing and Hearing Impairment: Violins as complex sound signal

Graphic:
Oscilloscope graph of violin playing. Example of complex tone as overlapping of simple tones.

In the case of complex periodic tones, several simple tones overlap to create one "overall tone" (sound).
With the violin, several simple tones overlap their upper harmonics to form "sounds" and the sounds and tones of several strings form complex "tone and sound mixtures". A complex periodic sound signal is formed through the combination of simple harmonics or partial tones.

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

Sprachen

Englisch

Dieses Material ist Teil einer Sammlung

Bild

Siemens Stiftung

The Ear, Hearing and Hearing Impairment;: Sound reflection - experiments

Experimentation instructions:
Experiment on sound reflection.

Without the metal plate, the ticking would be barely audible, but in the appropriate position, it can be heard very clearly: Sound waves are partly reflected when they hit an obstacle. The angle of incidence is just as big as the angle of reflection.

Information and ideas:
The experiment can be done in class together with the students.

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

Tuning fork - source of pure tones

Photo:
Musical instruments are tuned with the help of the especially pure tones of a tuning fork. But why does a tuning fork produce such pure tones?

With the help of a tuning fork it can be demonstrated that audible tones are often created by vibrating objects and that the tones depend on shape and dimensions of the objects. With a tuning fork all vibrations of undesired frequency are greatly attenuated or extinguished altogether. In the end only the tone which corresponds to the self-resonant frequency of the tuning fork remains. The tone is almost ideally monofrequent pure.

Information and ideas:
To check that this assumption is correct, the following experiment can be carried out:
A piece of glass covered in soot is placed on an overhead projector. A tuning fork is struck and the point of one of the tines is put carefully on the piece of glass and pulled along it.
The students notice that the vibrations of the tuning fork go "up and down" regularly. From this it can be concluded that tones are created when objects vibrate regularly.

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


Dieses Material ist Teil einer Sammlung

Bild

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

Bild

Siemens Stiftung

Microphone - transparent

Graphic:
With a moving coil microphone (dynamic microphone), the coil moves in "time" with the sound and produces a tone-frequency current.

In a microphone the mechanical energy of the sound waves is transduced into electric energy. From the mechanical vibrations the microphone produces an electric signal of the same frequency and amplitude.

Information and ideas:
Explanation of the process of sound transduction as it occurs in the inner ear of a human being using a technical device familiar to the students.

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