Web viewhas it bars set across a wooden box with an open top and a bottom that slopes downward toward the bass end. Different ranges of bars from alto to bass can be removed and inserted

Xylophone task report

Figure1: Mekoumbou Xylophone lay out.

HistoryHolmes believed that xylophone is an ancient instrument believes to be

originated independently from Africa and Asia. The common aspect of the

instrument is that all xylophones are made from the main component which

are Wooden bars with a variety of setup depending of some factors such as

cultural back ground or the maker technicality which in turn affect the quality

of the instrument.

The widest variety of xylophone are from Africa, including the one on figure

one above uses for Mekoumbou dance.

In the seventeenth century, African instrumentalists took the xylophone with

them to Central America where it was modified and became the Marimba. The

marimba remains popular throughout Mexico and Central America and is

considered the national instrument of Guatemala. The Africans who were

responsible for the instrument's migration also developed an effective method

of tuning by carving a gentle arch on the underside of each bar and simply

continued carving until the bar was tuned accurately.

The type of xylophone from Asia mainly invented in Indonesia known as

Trough, has it bars set across a wooden box with an open top and a bottom

that slopes downward toward the bass end. Different ranges of bars from alto

to bass can be removed and inserted in the box, so its range can be changed

to suit the music.

It is believed to be around the fifteenth century that the xylophone was

developed in Eastern Europe and it is in mid -1800s that western composers

discovered the instrument

Description

The xylophone is one of the most well known musical instruments around the

globe. It varies from cultures to cultures. Although different cultures have their

ways to build the instrument, it appears that almost all the xylophones have

similar tonality, which is the vibration of wooden bar in air when it is hit with a

mallet.

The xylophone belong to a family know as Idiophone.

Collins (1979) defined Idiophone as a class of musical instrument in which a

resonant solid material such as wood, metal, or stone, vibrates to produce the

initial sound, that itself forms the instrument’s body.

AnalysisThe diagram in figure 3 shows the time domain of the vibration of the

xylophone in air.

Mode 1 sine wave in blue color has a period time of half cycle per second,

representing a low frequencies and could be considered here as the

fundamental

Mode 2 in red color completes a cycle but in phase with Mode 1 at the

beginning of the second period

Mode 3 completes one and half cycle per second but not in phase either with

Mode 1 and 2

The analysis of these diagrams Mode 1, Mode 2 and Mode 3 suggests that

the frequency of the xylophone sound of the xylophone is aperiodic meaning

not in integer relationship.

Rogers (2003) developed a critical analysis of the diagram on figure 3 by

emphasizing on the relationship between the sum of the shapes that form the

sound as well as the base on which are attached the bars. He pointed out that

looking at the Mode 1 in Figure 2, it can be seen that there are two positions

(about 0.22 and 0.78) where the beam always has a displacement of zero. He

also mentioned that a xylophone bars are designed with two pins used to

attach each bar to the base, the importance being to allow Mode 1 to ring out

loud and clear, while disrupting all the other mode virtually making them

negligible.

Figure 2: xylophone time domain

Resonance of Xylophone bars: Analysis of frequency shift phenomenon:

Brancheriau L, Bailleres, Sales (2002) defined the xylophone as a percussion instrument made of vibrating wooden bars, the free ends of which can be struck by a mallet. The cross section of xylophone bars is not uniform for tuning purposes. They emphasized on the understanding of the frequency domain in acoustic resonance of xylophone bars during their tuning operation, which states the presence of one or several defects called weak elements in a bar considered as a one-dimensional system in free–free longitudinal and transversal vibration. Their analysis suggested that the weak element mechanically represents one or several real structural irregularities in the wood, corresponding to a mechanical behavior analogy and

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characterized by two positional parameters and by its Young’s modulus, resulting on their conclusion that:The frequency shift depends on the weak element position

along the bar When element weakens, the natural frequencies decrease

meaning that the frequency depends on the weak element along the bar.

Longitudinal and transverse dynamic behaviors are similar regarding the presence of a weak element in a bar.

An analysis on figure 4 below, show the frequency domain of a variety of

instruments plotted by using a spectrum analyzer and a microphone. The

analysis consisted to play the same musical note C on each instrument below.

Although the diagram shows that the fundamental frequency is the same for

all of the instruments, it appeared that the xylophone is the instrument with

least frequency content, with partials not in integer multiple relationship

Figure 3: frequency domain analysis

Bork (1989) suggested that the characteristic quality of xylophone sound depends, both on the enharmonic structure of its partials and on the order in which the individual partials decay.

Although xylophone seems to have the same tonality, it exist different types and forms. The tuning system and the setup also varies based on cultural group or technicality. The image on figure 4 below shows some different types of xylophone from a vast range worldwide but the main focus is on the Mekoumbou type, which is at the bottom of the figure

Figure 4: Different type of xylophone

Mekoumbou Xylophone:

Primary this type is one of the simplest type. It is not chromatically tuned. It is

made from a random set of notes predefined by the maker.

Each performer ensembles bars based on their playing ability. It is made from

red wood with large sizes bars, cut not in a random order.

Traditionally, Mekoumbou xylophone is ensemble during the performance

where bars are placed on two cut body bananas tree. Each bar has a hole on

one of its edge through which it is fixed on the banana body

Xylophone is at the heart of Mekoumbou. Two people usually play it, one for

the rhythm and the second for harmony called solo part. It is sustained by 3

pieces of bongo drum or more depend on the size of the event.

The rhythm is established by the rim shot, which in this occasion is a drummer

beating the edge of the table with hard wood or bamboo mallet in 1/4 + 3/4

beat per note. the Xylophone . Traditionally the Mekoumbou xylophone is

made from red wood, each piece with its own tonality, which does not

necessary fit in the Equal temperament of modern tuning system. For the

performance, each piece of xylophone has a whole on it and is attached to

two banana trees disposed on a table, but could also be disposed otherwise

depend on the technical ability of any group

The following link below demonstrates the kind of ceremonial into which the

Mekoumbou take place. It is executed for special events mostly during

funerals where the performance starts with a farewell and consolation to the

family that lost relative.

Tchanque (2012) stated that the Mekoumbou USA is a socio-cultural group

that promote the cultural diversity of Cameroonian culture in the American

territory.

Peter, R (2003). Vibrations Laboratory ME 4053 Lecture 2. Georgia Institute of Technology: Atlanta, Georgia [Assessed, 18 December 2014]

Holmes, G (2001) Xylophone .How Products are made: Encyclopedia.com [assessed, 12 December 2014]Tchanque, S. (2012). Tchanque Media Production [Assessed, 2 November 2014]