Drums

Terms and concepts discussed in this section:

Energy source
Energy transmission
Primary vibrator
Resonant vibrator
Sound effuser
Idiophone
Chordophone
Aerophone
1.Air chamber
2.Tonal chamber
3.External block
4.Tone holes
5.Chamfer
6.Fipple edge
7.Bernouilli effect`
8.Edge effect
Membranophone
Nodal lines
09.Radial modes
10.Azimuthal modes
11.Snares

Canadian Indigenous instruments are as refined and intricate as any in the world.  Likely, if an Indigenous crafter and a European instrument-maker were to meet, they would recognize one another immediately.  Whether drum or flute, mouthbow or violin; from east to west and across oceans, artisans have always understood and been one with wood, skin, sinew and the spiritual soul of their own communities.

The Musical Instrument

Worldwide, crafters work with five basic ingredients.  On these, they base their instruments’ more complex functions.

The energy source creates the sounds.  For a violin, a rattle, a drum, or a mouth bow, the source is the arm muscles.  For a flute or whistle, it is the mouth and airstream.

Energy transmission moves power from the source to the instrument.  Violins and fiddles use bows.  Mouth bows use sticks that hit the strings.  Drums use drumsticks, fingers or hands.  Wind instruments create an air column and use a flow control device, such as a reed, the way the musician’s lips vibrate, or a jet of air that the player directs across the embouchure hole.

The primary vibrator transforms human energy into sound.  Some instruments use strings. Drums use animal hides or membranes.  Winds use the airstream itself.

The resonant vibrator works with the primary vibrator to increase certain tones and harmonics and thus strengthen the musical sound.  The primary vibrator’s scattered frequencies move into the resonant vibrator.  These two share certain natural frequencies that constructively reinforce each other, thus making the sound not only more musical, but louder

This resonance does not increase the energy,  the law of the conservation of energy would forbid that, but rather it focusses the musical frequencies and rechannels the same energy.  The violin’s resonant vibrator is the instrument’s wooden body; the drum’s is the air volume that fills the frame and the flute’s is the air column inside the tube.  For the mouth bow, the mouth itself is this resonator.  Opening and closing the mouth accentuates the string’s desirable sounds.

The sound effuser, the way sound radiates out of the instrument, is the final component.  This includes the flute’s tone and end holes; the open mouth behind the mouth bow and the outer air in contact with the drum.  In European-style violins, the sound effusers are the holes in the violin’s body

The Four Categories of Musical Instruments

Idiophones are simple and produce vibrations when musicians play the instruments themselves.  This covers natural rhythm-makers as hollow logs, clacking sticks together or  directly working with thick hides.  This also includes notched-stick rasps, rattles, split-ash sticks (that the Mi’kmaq language calls ji’kmaqn) and the box drums of the Northwest Coast.

The sounds are strictly percussive, that is, they are not harmonic.  The various tonal partials are simply sound pulses.  However, Native musicians also use natural idiophonic resonators.  Inverted baskets or half-gourds become resonant vibrators when musicians play them.  Also, holes in the ground covered with wooden planks, metal or hide can increase vibrations. Other idiophones are objects that dancers attach to clothing, such as shells, bones or wood that jingle as the person moves.  More recently, Native women sew tobacco-tin cones on jingle dresses for powwow dances.

Only recently have musicologists recognized that Indigenous musicians developed various chordophones prior to European  contact.  These instruments include the mouth bow. This is simply a string stretched tightly between two ends of a bent stick.  As discussed earlier, the musician holds this against the cheek to send sounds to the mouth cavity.

In addition Indigenous people stretch a sinew across the arc of a caribou shoulder blade to create a one-string fiddle.  The musician plays this instrument with a sinew-strung bow. The tautirut of the Eastern Inuit might be a form of zither or fidla.  Closely related forms exist in northern Scandinavian countries and the Orkney Islands.

Later crafters began modelling chordophones on instruments traders and trappers brought from Europe.  These include stringed instruments that work like violins and guitars.  To make these instruments, crafters usually fasten strings to two fixed points at the ends of a wooden or metal body.  Like a fiddle or guitar, a bridge transfers the vibrations into a resonant vibrator.

A string’s fixed length partly controls a chordophone’s frequency.  But, the string’s other characteristics, its tension and thickness, still allow the musician to change the frequencies.  For example, a heavier string will vibrate more slowly than a lighter one.  If the musician tightens both heavy and light strings, they will produce ever-higher frequencies.

Harmonics depend on whether the musician bows or plucks the strings and the points at which this takes place.  A chordophone’s string is the primary vibrator, but it is unique because the instrument itself, not the resonant vibrator, creates the musical frequencies.  Once the string’s vibrations move into the instrument’s body, the resonant vibrator simply reinforces those frequencies, rather than actively selecting the musical tones.  A chordophone’s body, therefore, usually is irregular, which increases the number of frequencies it can resonate.

Aerophones are instruments in which vibrating columns of air radiate sound.  Among Native peoples, whistles and horns are common aerophones.  But, here we will discuss one of Indigenous North America’s most distinctive instruments: the flute with external block.  Musicologists classify the Indigenous flute as a flageolet.  This is because the flute’s mouthpiece is at the instrument’s end and the musician blows directly into it.  (A European analogue would be the recorder).  However, people commonly call the Native instrument a “flute” so we will do the same.

The flute has four important parts: the air chamber, the tonal chamber, the external block (also known as a saddle or baffle) and the finger holes.  The airstream moves through these as follows.

When the musician blows through the flute’s mouthpiece, the airstream first enters the air chamber, a short section that a plug separates from the tonal chamber.  Reaching the plug, the air takes the path of least resistance: a small hole bored in the air chamber’s upper wall.  The airstream then runs into a chamfer, essentially a slot that directs the air towards the tonal chamber.  The chamfer is either a small metal plate the external block holds in place, or the flute-maker can carve it directly into the block’s underside.  The airstream moves down the chamfer, then reaches a hole that leads into the tonal chamber that comprises the rest of the flute’s body.  Unlike the hole in the air chamber, the hole leading to the tonal chamber also opens slightly to the outer air.

At this point, the airstream responds to the Bernoulli effect: the principle that moving air has less pressure than air that is standing still.  When a musician blows through a flute, the lower-pressure moving air creates a sideways suction that disturbs the air around it.  We call this an edge effect.  The airstream emerges from the chamfer and strikes the fipple edge, the sharp boundary of a window in the upper wall of the tonal chamber.  The Bernoulli effect sucks most of the air downwards into the tube.  However, the suction also pulls some of the excess air from above the fipple edge into the tube.  Scientists think this suction whirls the excess air inside the tube.  This, under greater pressure, moves back to where the pressure is lower, that is, above the fipple edge.  When the air reaches the space above the fipple edge, the air stream’s continuing suction pulls it down into the tube again.  This creates a tone in much the same way as blowing across a pop bottle’s opening.

These events continue for as long as the musician blows, but varies depending on how fast the air moves.  In a flute, the complicated vibrations across the window’s edge produce an interesting variety of musical sounds.  This is where the external block can earn its alternate name of “tuning block.” If the block is adjustable, the musician can move it back and forth to change the window’s width.  This affects the flute’s tones.  A narrow window, for example, emits sounds closer to a pure tone with fewer harmonics, while a wider window allows richer and more diverse tones.  Also, the way the crafter forms the channel in the flue affects how many harmonics the instrument can produce.

The tone holes along the flute’s body also contribute to tonal variety.  When the musician’s fingers cover all the tone holes, the wave inside the tube must travel down the entire tube before it can exit at the lower end.  This produces the lowest possible sound, so the tone is the fundamental frequency.  But, if the player begins uncovering the holes, the air path shortens and the frequency rises, which elicits progressively higher pitches.

Crafters produce a wide variety of flutes, each with its own sounds.  People traditionally measure the Amerindian flute from the index finger’s tip to the elbow: an average 20 inches.  Longer and wider flutes produce lower-pitched scales.  Also, the spacing and tone-hole sizes affect the pitch and timbre of the tones.  Indigenous cultures have not set up any fixed standards, but their final goal is to create flutes that produce a pleasing tonal quaver (or tremolo).  Native peoples prefer this quality, especially in the instrument’s lowest pitch.

Membranophones are drums: percussion instruments that stretch an animal hide (membrane) across a wooden frame, or even over a hole in the ground.  A drum’s vibrations are far more complex than those of strings or air columns.  While the latter two are one-dimensional media, the membrane is two-dimensional and thus its vibrations act in different ways.

In certain respects, a drum is like a wide string.  The membrane doesn’t have two fixed nodes.  Instead, the entire frame supplies the tension.  Like a string, the membrane’s frequencies rise as the tension increases (as the membrane tightens across the frame).  Similarly, the frequencies are lower if the crafter uses thicker and heavier membranes.  When the drummer strikes the membrane, it vibrates in all its modes at once.  The drum also has points that do not vibrate, but since the membrane is two-dimensional, these nodes become nodal lines.  Rather than single points, the most vibration-free line forms a ring where the membrane connects to the frame.

But, that is about as far as the likenesses go.  The membrane can vibrate in two different ways:  where nodal lines are circles (radial modes), and where they are diameters of a circle (azimuthal modes).  This creates radically varying vibratory modes, all acting at once as the whole membrane moves in phase.  These simultaneous vibrations move a lot of air, and thus the membrane’s sound energy spreads out strongly.  Also, the membrane heavily damps the sound, in other words, the tones decay quickly.  Strings, in contrast, can vibrate a long time.

Because the membrane’s different vibrations often compete with one another, the waveforms vary from one cycle to the next.  Drummers can use this if they decide to strike the membrane at different points on its surface to produce different kinds of sounds.  The effect is similar to plucking a string at different points.  In both cases, this affects the kinds of sounds the instruments will produce.

Unlike the string, however, the drum has a wider variety of vibrations.  In fact, an ideal membrane can have  as many as 12 vibrational modes .  This would require a membrane  exactly even in thickness and density.  But, in reality, a membrane will vary considerably and produce complex and non-periodic tones.  For this reason, many drums do not seem to favour a specific pitch.  However, some drum makers have learned ways to obtain an exact pitch.  They can,  for example, carefully construct the enclosed air cavity (kettle drums), or skillfully apply layers of black paste to the membrane (tabla of India).

Even though the drum is a percussive instrument rather than melodious, it features a far wider array of possible tones than the basic idiophone.  Indeed, some Indigenous singers will pitch their singing, subconsciously or consciously, to match a particular drum’s tone.

To achieve these tonal varieties, a crafter must create a drum whose sound pulses will be loud, strong, and resonant.  The drum’s frame is a crucial resonator.  Like a guitar or violin string, a membrane itself produces little sound.  The sound wave’s air condensations on one side match the rarefactions on the other.  Simultaneously, the opposite phases cancel one another out.  However, once the crafter attaches the membrane to the frame, the sound wave from the underside cannot interact and cancel the sound wave from the upper.  The enclosed cavity of air, shallow as it might be, provides the necessary divide between the membrane’s two sides and increases its radiating ability.  Additionally, if the drum is closed on both sides, for example, a double headed drum, it will have unique vibrational characteristics.  Closing the air space generally lowers some of the overtone frequencies.  This is why powwow drums historically have become larger.  The double head and the larger airspace produce a fuller, more resonant and deeply lower pitch.

Besides these natural variations, Indigenous musicians have learned to adjust a finished drum to maintain the deep, resonant tones they desire.  The membrane’s tension and thickness (weight) determine the natural frequency at which it vibrates, but other variables also affect the way it sounds.  The problem is that temperature and humidity stretch or shrink the membrane, which changes its pitch.  Cool, moist weather causes both the hide and the pitch to become loose and limp.  Hot, dry weather stretches it too tightly, making the sound high-pitched and tinny.

To offset these effects, a drummer will heat or cool the drum’s membrane before playing.  If the hide is wet and flabby, the musician will hold the drum over a fire or use a heater or hair dryer, which causes the membrane’s pores to contract.  It the hide is dry and tight, the drummer will brush in drops of water to loosen the skin and lower the tone.

Indigenous musicians also use other methods to improve this basic tone.  A drummer often will loosen or tighten snares, usually twisted hide or gut, that stretch over or under the membrane.  When the musician strikes the drumhead, these snares vibrate against the membrane, producing a buzz tone about one octave lower than the drumhead alone.  Also, to provide even greater tonal effects, sometimes crafters wind small bones, sticks or feathers into the snares.  Like stringed instruments, these snares have harmonic qualities that, when combined with the drum’s full tonal array, create a rich and fluid soundscape that changes with every strike.

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Native Drum