Edinburgh University Collection of Historic Musical Instruments

How to use The Sound Laboratory

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Sound tables

Visitors can excite strings under tension (i) without any soundboard, (ii) with a simple soundboard and (iii) with hollow soundboxes of different sizes. Striking differences can be heard and the unit gives an introduction to the development of string instruments.
  1. String without any soundboard

    Pluck the string and listen

    A vibrating string produces little sound because the surface area of the string is so small that the quantity of air which it can displace is tiny. There is not enough coupling with the air.

    Pluck the string and press metal mounting onto the table top - hear the difference !

  2. String with a simple soundboard

    Pluck the string and listen. Compare the sound with the above.

    What is the effect of adding a bridge and a soundboard ?

    In string instruments, the bridge transmits the vibrations of the strings to the soundboard, while filtering the sound so as to remove any squeaking. The soundboard plays an essential role in the amplification of the sound: it transmits the energy of the vibrating string and damps it by vibrating itself; the sounboard surface offers sufficient contact with the surrounding air that the sounds become audible. Certain string instruments such as the piano do not have a soundbox because their soundboard is large enough to radiate the sound.

  3. Strings with hollow soundboxes

    Why does the sound last longer with soundbox ?

    In stringed instruments, the soundbox plays an essential role in the radiation of the sound: the table quickly transmits the energy of the initial vibration to the surrounding air, in particular that contained inside the soundbox. This air vibrates in sympathy and prolongs the sound. This is important for instruments like the guitar.

    Why are the deep instruments such as the double bass equipped with a larger soundbox than high instruments such as the violin ?

    Pluck the strings and compare the sound output of similar strings mounted on soundboxes of different volumes.

    The lower the frequency of a sound emitted by a string (i.e. the thicker the string is for a same length), the greater the volume of air in the soundbox is needed. The vibrating volume of air inside the soundbox strongly influences sonority.

  4. The Clavichord

    How can a single string produce different sounds ?

    Press on the keys on the clavichord. For a stable sound, keep the key pressed dowm. What happens ?

    When the metal tangent fixed on the key strikes the string at a particluar place, it causes the string to vibrate in the following way: where the tangent touches the string there is a "node of vibration", this point on the string remains motionless. The portion of the string to the left is damped, so only the portion on the right vibrates strongly.

    The keys are positioned so that they create the node at the places where the sounding lengths are related by simple numbers (1 : 7/8 : 5/6 : 3/4 : 2/3 : 3/5 : 9/16 : 1/2) to sound a major scale. The string lengths for the octave are the simplest ratio, 1/2.

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Bowed strings

Visitors can experiment with different bowing speeds and pressures to understand the basics of violins and other bowed string instruments. The unit channels the interactive element to give a clear demonstration of these two parameters.
  1. Bow a string on the violin by pulling and pushing the bow.

    Observe the image of the sound on the screen.

    The saw-tooth shape of the waveform indicates that the bow hairs alternately grip and release the string, this "stick-slip" action causes the string to vibrate. The period of grip by the hair is longer than the time the string takes to slip back. The quicker the return, the more rich in overtones the generated sound.

  2. Vary the speed of bowing and the force of the bow on the string. Listen to the sound and see the waveform change on the screen.

  3. Try to produce the most pleasant sound, the most unpleasant sound.

    A smoother curve indicates a lower noise content.

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Vibrations in air columns and in strings

The difference between longitudinal and transverse vibrations. Visitors actuate vibrations in a spring (simulating an air column) and a long overhead string (simulating a string on a guitar or other string instrument).
  1. The end of this string goes up and down at a certain frequency. This vertical movement is propagated along the string in the horizontal direction. When the vibration occurs in the direction perpendicular to its propagation, like the case of this string, it is said to be "transverse" vibration.
  2. The end of the spring goes up and down at a certain frequency. This vertical movement is propagated up and down the spring verticallly. When the vibration occurs in the same direction as its propagation, as the case of this spring, it is said to be "longitudinal".

    Sound waves in air are longitudinal vibrations; the pressure of the air varies and it is this variation that is propagated.

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Sounding a trumpet

A real trumpet is actually played by an artificial embouchure, the visitor controls air pressure and the valves and hears the results. As the air column resonates, the waveform and the spectrum are displayed on a computer screen, which also provides interpretative material.

1. This is a real trumpet, however the human lips are replaced by water-filled balloons and the air pressure is supplied by a pump rather than human lungs. The resulting sound is not very exciting musically, but is predictable and can be sustained indefinitely, allowing us to sample the sound and study how a trumpet works.

Turn to the computer and find the following screen. Click on Main Menu if you find a different screen when you come to the computer.

Click on the box with your choice of language: Dutch, English, French or German.

2. If you are not familiar with using screen-and-mouse controls such as the sliders, learn how to use them by clicking on Introduction to Graphical Controls. Otherwise, click on Next Screen

3. At this screen, select Wind Instruments and use the programme to explore the way a trumpet works.

4.  Select Sampling a Sound. Sound the trumpet by turning the air valve on and while it is sounding click on New Sample with the mouse. This can be repeated with the valve pressed - hear and see the difference when the trumpet's tube is lengthened.

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Sounding a clarinet

A real clarinet is actually played by an artificial embouchure, the visitor controls air pressure and one of the keys and hears the results. As the air column resonates, the waveform and the spectrum are displayed on a computer screen, which also provides interpretative material.

1. This is a real clarinet, however the human lip is replaced by a rubber tube and the air pressure is supplied by a pump rather than human lungs. The resulting sound is not very exciting musically, but is predictable and can be sustained indefinitely, allowing us to sample the sound and study how a clarinet works.

Turn to the computer and find the following screen. Click on Main Menu if you find a different screen when you come to the computer.

Click on the box with your choice of language: Dutch, English, French or German.

2. If you are not familiar with using screen-and-mouse controls such as the sliders, learn how to use them by clicking on Introduction to Graphical Controls. Otherwise, click on Next Screen

3. At this screen, select Wind Instruments and use the programme to explore the way a clarinet works.

4. Select Sampling a Sound. Sound the clarinet by turning the air valve on and while it is sounding click on New Sample with the mouse. This can be repeated with the key pressed - hear and see the difference when the clarinet's sounding length is changed.

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Strings and percussion

Visitors can hammer a thin string, a thick string and a metal bar mounted on a soundbox and hear the results and see the basic difference between the piano and the marimba. The waveform and the spectrum are displayed on a computer screen, which also provides interpretative material.

  1. The string on the left is like a piano string; the bar on the right is like a marimba bar. The thick string in the middle is not like the sounding part of any usual musical instrument. Hit each one and listen.

    The computer can explain why the effects sound different.

  2. Turn to the computer and find the following screen. Click on Main Menu if you find a different screen when you come to the computer.

    Click on the box with your choice of language: Dutch, English, French or German.

  3. If you are not familiar with using screen-and-mouse controls such as the sliders, learn how to use them by clicking on Introduction to Graphical Controls. Otherwise, click on Next Screen

  4. At this screen, select String instruments and use the programme to explore the way a string instruments work.

  5. Select Sampling a Sound. Sound the thin and thick strings and the bar, and while each is sounding click on New Sample with the mouse. See how the waveforms and spectra are very different.

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    Instruments Workshop

    If you change the shape of a cello or make it from another material instead of wood, what happens to the sound ? Enter a virtual instrument manufacturing studio using this sound synthesis program. Learn how stringed, wind and percussion instruments are made and then try your hand at recreating a mystery instrument piece by piece.
    1. Find the Instruments Workshop computer. Click on Main Menu if you find a different screen when you come to the computer.
    2. Click on Start.
    3. Select a language: Dutch, English, French or German.
    4. Select Instruments Workshop
    5. Explore the families of instruments. There are similar instruments here in the museum and you can see many more in most of the classes described. Some of the instruments pictured are actually here in the museum - see if you can find them.

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    Reconstruct a Sound

    What distinguishes a violin from a trumpet ? What are the musical components of a sound ? What is harmonic richness ? Try to resonstruct the sound of different instruments; observe how sounds are analysed and visually represented by sonograms.
    1. Find the Instruments Workshop computer. Click on Main Menu if you find a different screen when you come to the computer.
    2. Click on Start.
    3. Select a language: Dutch, English, French or German.
    4. Select Reconstruct a Sound
    5. Find out what determines the sound quality of an instrument, and how difficult it is to identify instruments from a short sample of the sound.

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    Exploring Timbre

    Mellow, tinny, blaring ... each instrument has its own distinctive timbre, or tone colour. In fact each musician has a distinctive way of playing an instrument, his or her own specific timbre readily recognisable by music lovers. Explore this notion by manipulating the sounds, and by comparing instruments and some famous musicians.
    1. Find the Exploring Timbre computer. Click on Main Menu if you find a different screen when you come to the computer.
    2. Click on Start.
    3. Select a language: Dutch, English, French or German.
    4. Explore the different ways instruments sound different, and how players can control sound quality.

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    Links to further information

    See where and when to visit the Sound Laboratory

    See further information about the Sound Laboratory

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    © Edinburgh University Collection of Historic Musical Instruments, 2000.

    This page updated 11.1.00