Sounds of Music

Sounds of Music is an event in which two participants build two instruments, play two songs in a performance taking up less than 4 minutes, and explain the physics of sound through an interview or written test.

The Instruments
The main part of Sounds of Music is the building of the instruments. You will need to build two durable, original, and creative instruments with which you will play two pieces of music. You will also need to answer questions about the theory of your instrument and how you built it.

Building an Instrument
For this year's competition, you'll have to build two instruments: One must be a wind instrument (an aerophone, see below) and one must be a percussion instrument (an idiophone or membraphone). Note that chordophones and electrophones are NOT allowed.

When building your instruments, you'll have to be creative. No commercially available instrument parts are allowed, (i.e. mouthpieces, mallets) excepting strings. Experiment with different materials. PVC Pipe is a common material that is cheap and easy to make into an instrument; many teams will make PVC pipe aerophones.

Another common instrument under this year's rules is the xylophone. You will also want to experiment with materials if you are building one. Try different types of metal pipes and different types of wood to see what works best. There are several resources online that will give you the exact length to build the bars, but you will need to fine tune these so you get the exact pitch.

When building a xylophone you will also need to consider the material with which you build the mallets. If you use a soft material such as rubber or yarn, the percussion instrument may be drowned out by your wind instrument. If you use harder materials, the xylophone will be heard but the tone quality may suffer. Once again, you'll have to experiment to see what suits your playing style best.

Remember that your instruments MUST be in the allowable range. Your percussion instrument will be in the bass clef range (G2 to G3) and your wind instrument will be in the treble clef range (C4 to C5). It is not uncommon for teams to get knocked down a tier or two because they are in the wrong octave.

There are four basic classifications of instruments under the Hornbostel-Sachs system as shown below. The fifth, electrophones, was not included for several years after the creation of the Hornbostel-Sachs system and is not used in competition.

Idiophones
In idiophones, the vibration of the instrument itself is what creates sound. They are generally the percussion instruments that are hit, shaken, or rubbed to create sound. Resonators can also be added to these instruments to create a sound.

In this event, the major type of idiophones created are xylophones, marimbas, or chimes. So when you double the length of a bar, you cut the frequency in a fourth (put it down two active octave). So in these instruments, to go down an increment of the scale, you must decrease the note length by a factor of the 24th root of 2. These also require you to fine tune (sand/file).

Examples of idiophones include
 * Xylophones
 * Bells
 * Steel Drums
 * Wine Glasses

Membranophones
In membranophones a vibrating membrane over a resonator creates sound. This would be rather difficult to build, and I wouldn't advise it.

Examples of membranophones include
 * Tuned drums
 * Timpani
 * Kazoo (not sure whether your judge would like it though...and you'd need perfect pitch)

Aerophones
In aerophones, sound is produced by a vibrating column of air within the instrument. Pitch is changed by changing size of vibrating air.

Examples of aerophones include
 * Flutes
 * Pan Flutes
 * Tubas
 * Trombones
 * Horns/Trumpets

Chordophones
 '''NOTE: Chordophones are not allowed under the rules for 2011. They may be reinstated in a later year, but for 2011 chordophones are disallowed.'''

In Chordophones, sound is produced by a vibrating string. The vibration of strings produces standing waves producing fundamental frequency as well as harmonics (the relative abundance of these make up the timbre of your instrument). Resonators added to the string will enhance the sound by vibrating sympathetically with them.

In chordophones, the wavelength made is twice the length of the string. Since we know that velocity equals frequency time wavelength, after assuming that the velocity of sound in the string will remain constant, we find that when one doubles length, frequency will be cut in half (note goes down an octave). Because the relationship between length and frequency is exponential we know that for every increment one goes up in a scale (1/12), the note increases by a factor of the 12th root of two. You can use this fact for starting your tuning. Unfortunately, you'll need some fine tuning and many hours to get your instrument to play accurate notes due to imperfections in string and to the fact that there will be different amount of tension on different strings (when playing different notes on single guitar string, there will be different amounts of tension). This will result in different velocities of sound in the string...making this form of tuning less reliable.

Examples of chordophones include
 * Guitars
 * Violins
 * Harps
 * Zithers
 * Lyres
 * Piano/Harpsichords (a bit hard to make, not really advised)

Electrophones
 '''NOTE: Electrophones are not allowed under the rules for 2011. They may be instated in a later year, but for 2011 electrophones are disallowed.'''

Concerning electrophones, sound is produced by an electrically powered oscillator. It is highly unlikely anyone will build this type of instrument for Sounds of Music anytime in the near future, and it is also barred from competition under 2011 rules.

Examples of electrophones include
 * Theremins
 * Synthesizers

Technical Interview
The technical interview generally becomes more important as the year goes on (and the competition becomes tougher). This is because your opposition usually gets tougher as well and many more instruments sound 'real'. Because of this, the interview will become a huge separator of teams. Make sure you understand the physics of sound and wave theory, basics of resonance, basics of tempering, and go into as much depth as possible into how your own instruments function. Many people take this part of the competition lightly, but 30 points is nothing to scoff at.

The following website provides much of the knowledge needed for the technical interview portion of sounds of music

Instrument Instructions
Here are websites with tutorials to make instruments:


 * Woodwinds
 * Whistle


 * Strings


 * Brass


 * Percussion