Unleash the Hidden Bank of Sounds in Your Acoustic Piano

October 18, 2013
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  There’s a multitimbral percussion kit inside your acoustic piano. By placing objects on or among the strings, you can create a universe of new and useful sounds while retaining the action and dynamics of a real piano.



 

Background Check

Fig. 1. Common objects that work well for preparing a piano, including screws, felt, and erasers.Prepared piano is a simple concept that uses everyday items to quickly and safely modify the timbre of the strings. Common objects from the home and garage can do the job (see Figure 1).

The interior of the piano has been fair game for performers and composers since Henry Cowell pioneered the use of hands on the piano strings in pieces such as “Aeolian Harp” and “The Banshee.” But it was John Cage who brought the term “prepared piano” into common usage. Cage developed the idea out of necessity: He needed to produce a variety of percussive sounds to accompany dancers when there was no room for extra musicians onstage. He settled on the idea of altering the sound of the strings by adding such objects as screws and bolts, and further refined the technique as he composed more works for the instrument.

Development of the prepared piano didn’t stop with Cage. Piano interiors have been a playground for film composers for decades, and improvisers in all musical genres have been known to reach into the piano and lay a hand across the strings to get muted timbres, or touch a string lightly to get harmonics.


Handle with Care

There is only one rule for working inside the piano: Do no harm. The preparations you use should be based as much on the owner’s feelings about the instrument as on what sounds you’re looking for.

Some piano owners are absolutely against foreign objects, even the player’s fingers, touching the strings. This is totally understandable and must be respected: A grand piano is a major investment and a precision instrument. In these cases, graciously step away from the piano.

Other piano owners may be skeptical at first, but have an open mind about using the piano interior as long as you promise not to do damage. If you keep the following guidelines in mind, you can assuage their fears. When I inquire about preparing a piano for a concert or recording, I pull out my non-metal objects first to show that some of the materials I use are no different than a piano tuner’s (e.g., rubber and felt inserted between the strings).

Even if your hands are clean and dry, oils from your fingers get left on the strings when you touch them. These oils attract particulates that hold moisture and eventually oxidize the metal and lead to corrosion. On a new piano where the copper-wound strings are still shiny, your fingers will leave black marks or dark lines, which cannot be safely removed. If you use clean gloves and work carefully, you can avoid skin-to-string contact. Not surprisingly, new piano strings are the most resonant when prepared. However, the majority of pianos you’ll run across will not have shiny wound strings, so finger contact is less of an issue.

Technicians recommend that you protect the dampers by pressing down the sustain pedal before inserting or removing anything from between the strings. This keeps the damper’s felt pads and wedges from being damaged or misshaped as you spread the strings apart with a preparation.

Take special care not to touch the moving parts of the action. If a hammer or damper gets pushed out of alignment, repairing it can be an expensive proposition.

When selecting an item for use in the piano, be sure the object’s diameter is similar to the distance between the strings, so that the preparation doesn’t inordinately increase the string tension. Similarly, keep the preparations away from the agraffe and bridge pins at the ends of the strings. The middle portion of a string’s speaking length is the safest and easiest to prepare, though this can become an issue as the strings get shorter at the top of the instrument’s range.

Never force a preparation between the strings. The safest way to insert metal objects such as bolts and screws between the strings is to turn the flat blade of a screwdriver between the strings to gently part them enough to place the preparation. Remove the preparation the same way. Rubber, felt, and wood are usually simple to insert and remove. 

Be sure that your preparations, such as screws and bolts, do not scratch or gouge the soundboard. And keep them away from the area above the hammers and piano action, because occasionally items fall into the piano. Things that fall onto the soundboard can be removed by pushing them toward the lower strings with a piece of paper or card stock. 



Every Piano Is Different

Pianists know that every instrument will offer surprises—and that’s just from the action, tuning, and timbre. Look inside grand pianos from five different manufacturers and you’ll see structural differences.

The differences you’ll notice include overall string lengths, the number of strings per unison in each register, the type of strings in the lower register (copper wound or plain steel), the distance between strings, and the point where the bass strings cross over the lower midrange strings. Consequently, a specific preparation you have for a note on your personal instrument might not translate to other pianos when you travel.

For example, from one instrument to the next you will find that different areas of the lower mid-register strings cross under the bass section. When much of the string is inaccessible, certain preparations becomes difficult or impossible. Another common issue is that a screw or bolt that works well in one piano will be too narrow or wide for another because of differences in the spaces between strings. The locations of braces and cross beams within the piano can also make it difficult to place objects in specific spots.

So be ready to improvise with your preparations when you change pianos. Cage had this in mind when he wrote, in the Foreword to Richard Bunger’s book, The Well-Prepared Piano (1981, Litoral Arts Press), “Instead of the possibility of repetition, we are faced in life with the unique qualities and characteristics of each occasion.”


Surface versus Internal Preparations

Nearly anything you can do to a guitar, bass, or violin string can be done to the strings of a piano, such as strumming, muting, bowing, or isolating a harmonic by touching the nodes on a string. Surface preparations—objects placed on the strings such as a book, a ring of keys, or a sheet of paper—are good for changing the timbre of range of notes. The objects should be heavy enough that they don’t bounce out of position as you play, unless the sound of it bouncing is what you’re after. For example, lighter objects with curved bases, including cymbals and gongs, can be set into a rocking motion to create trill and glissando effects.

One of the most effective surface preparations is a magnet. If it’s strong enough, it will add mass to the string and create a lower sound, similar to what an internal preparation does. However, placing and removing a magnet can be done quickly. The strength of the magnet determines where on the instrument it can be used: Because the lower strings are larger, you’ll need a fairly strong magnet for this range or it will pop off when you play. Round magnets are good for covering one note, while long rectangular magnets can reach across several strings.

Another favorite surface preparation, and one that is equally easy to place, is a layer of clear packing tape across the highest notes of the instrument. The resulting sound is a high-pitched pop that works well on its own or blended with lower notes. I often place a small ball of plumber’s putty on strings in the middle and upper registers to get a percussive sound with a softer attack and shortened decay.

Internal preparations are objects placed between the strings. Here, you have the opportunity to shape the unique characteristics of each note of the piano, such as its overtones and envelope. The material you choose—metal, wood, felt, paper, plastic, stone—will have a large impact on the sound you get. 

Let’s take three common objects to represent the different materials—a dime (metal), speaker wire (plastic), and a golf tee (wood)—and see how they affect the sound of the trichord strings. You’ll get a resonant gong-like sound by weaving a dime between the three strings of middle C. To insert the dime, press down the sustain pedal and tuck the dime under the middle of the three strings so that the edges of the dime sit on top of the outer two. (Be careful that the sides of the dime do not touch adjacent strings, unless you want to add some extra buzz.) The notes you’ll hear in the resulting tone cluster will depend on the dime’s lateral position on the string. Fine-tune the sound by sliding the dime in either direction along the string.

Note that the sound is lower in pitch than the natural note. That’s because you’ve added mass to the string.

The speaker wire, in contrast, sounds less resonant, but still yields a rich mix of harmonics. When used in the upper register, rubber and plastic preparations offer a nice woody texture with variable decay based on their position along the string. You can get a similar effect in the low octaves by placing large rubber pencil erasers between strings. Because the bass strings are longer, you can emphasize specific harmonics and fine-tune the note’s decay based on the position of the eraser.

When used with a trichord note such as middle C, the golf tee adds a new dimension to our preparations because it leaves one of the strings untouched. As a result, you will hear the normal pitch mixed with the complex harmonics of the prepared strings. This is where the grand piano’s una corda, or soft pedal, comes in.

The una corda shifts the entire keyboard to the right so that the hammers hit fewer strings—the middle and right strings of a three-string unison—leaving the left string to vibrate sympathetically. If you place the golf tee between the middle and right string of the trichord, then play the note while pressing down the una corda pedal, you will hear only the prepared note (see Figure 2). Release the una corda pedal and play the note again to sound the normal and prepared notes simultaneously. Two different timbres are available from one key. By putting a tee on either side of the middle note, you can use the una corda pedal to switch between two prepared sonorities.

You can tap on these preparation directly with a pencil or chopstick for a more percussive sound than you get by playing the keyboard. However, the fragility of the object you’ve used will determine how hard you can strike it, and the results might be quieter than if you played it from the keyboard. In a recording situation, or onstage with a miked piano, tapping on the preparations is usually loud enough to be heard clearly.



Bowing

Few sounds coming from a piano surprise an audience more than sustained ones. Although a traditional bow doesn’t adapt easily to the piano, making one that does is simple.

The low-cost method is to cut a 2- to 3-foot length of monofilament fishing line and coat it with bow rosin. Often, I’ll use two or three lengths of the line and tape the ends together with duct tape so that the strands don’t tangle. Rosin dust can be removed from the piano strings with a clean, dry cloth.

When your bow is ready, weave it under a piano string, press down the sustain pedal, and pull up on either end of the line while moving your hands back and forth. If you bow trichord notes, you’ll mostly activate the outer strings, and the middle string vibrates sympathetically.

Another effective bowing technique is to use rosined popsicle sticks or coffee stirrers, as are found at the condiment bar of every Starbucks. Add some rosin to one end of the stick and rub it up and down against the side of a string: instant string tremolo.

Lateral bowing can be done with a small square of rubber from the inner tube of a bicycle tire. The resulting sound is made up entirely of upper partials. Wrap the piece around your index finger, hold down the sustain pedal, and drag the rubber along the length of the string. 

The pianist’s secret weapon is the Heet Sound EBow (ebow.com). Designed for guitarists, the EBow is a battery-powered, hand-held device that causes a metal string to vibrate (see Figure 3 at left). The underside of the device has ridges that are designed to sit on the guitar strings on either side of the one you want sustained. Because the piano’s strings are closer together, you’ll typically excite only the middle of the three strings in the trichord. 

The tone that the EBow gives you is pure, sonorous, and almost synth-like. The newest model, called the PlusEBow, has two settings, one of which causes the string to play an octave harmonic. If you press down hard enough on the EBow while playing, the piano string will vibrate against the device and create a distorted sound that is very pleasing. The best part about using an EBow in the piano is that the audience can’t see what you’re doing, so you’ll get their attention immediately.


 
 

 

Always Be Prepared

These are by no means the only ways to prepare a piano, but merely a starting point for further exploration. I strongly recommend reading Bunger’s The Well-Prepared Piano (available from richardbevans.com), which goes into great detail about material choices, hybrid preparations, and approaches to notation and performance. 

Once you get started, you’ll have fun experimenting with items from around the house placed inside the piano. And don’t forget to record what you do: you never know when you’ll find the perfect sound to add to your sample library.

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