“A Thousand Different Sounds”: Tone Quality at the Piano
The question of tone quality comes up amongst pianists regularly. It is often said that no matter what the pianist does all that matters is the speed of the hammer when it hits the strings. This is partially true from the point of view of physics where all that is taken into account is the relationship between the fundamentals and partials. But what we consider to be “tone quality” is a result of a complex and fascinating combination of the mechanics of the instrument, the body, and human perception. Without getting too technical here is a brief overview:
1. Pitch and Timbre
Pitch generally corresponds with frequency. The higher the frequency, the higher the pitch. Few sounds are made of pure, regular sound waves. The number and intensity of overtones (partials) are what allow us to distinguish between a harp and a violin. This can be described as timbre.
2. Human Sensation
Our bodies react to external stimuli via the end organs of the inner ear (fine hair-cells), our retinas (rods and cones) and through touch (bulbs beneath the skin). In piano playing we are primarily concerned with auditory stimuli but when we play the piano or watch the piano being played our vision and touch can also play significant roles in our perception of tone quality.
3. What is tone quality?
What we perceive to be tone quality is a result of three different attributes combined to create a single aural experience.
a. Pitch- frequency
b. Intensity- tonal loudness
c. Duration- length of time the pitch is sounded
Each of these elements can vary greatly. It is through combining these elements that a vast array of tone colors are created at the piano.
4. Ortmann and the Oscillograph
Otto Ortmann, was an American educator who served as director of the Peabody Conservatory from 1928 to 1942. Beginning in the 1920’s Ortmann and other researchers began using a device called the oscillograph to record and create graphic representations of sound waves.
The results were fascinating. For instance, the higher a pitch is played on a trombone, the fewer partials are present and a more pure tone quality is produced.
The greater the intensity (loudness) of a mezzo-soprano when singing A=440 the greater the complexity.
The shorter the duration of a sound on the piano the more noise and less tone we perceive.
4. Percussive and noise elements
When we play a key we hear not only the tone produced by the instrument but also how percussively the key is played and mechanical noises produced by the instrument (finger-key impact, key-bed impact, hammer-string impact, hammer-check impact, and friction among the action parts).
A percussive sound is created by striking the key from above. A non-percussive sound by staying close to the surface of the key.
Ortmann showed in his research that these noise and percussive elements affect the way we perceive the quality of tone. Subsequent research, including this study published in Novemeber 2014 issue of “The Journal of the Acoustical Society of America,” support that view.
A fascinating blog post on the study can be read at Physics Central:physics buzz blog.
As Ortmann notes, the effect of duration in piano playing is particularly striking as the human ear is not capable of separating the noise elements present at the beginning of a tone from the tone itself. When the noise elements were removed in the recording studio even professional musicians were unable to identify the tone as being produced by a piano, and instead guessed double bass, flute, violin, and other instruments.
The piano does not sound like a piano without a human being playing it.
5. So how do we create different sounds at the piano?
I. Varying the speed of the hammer hitting the string
If you want to create a soft sound at the piano play slowly into the key. If you want to play loudly, play fast. However, volume is not the only thing that is altered by varying the key speed. The mix of overtones shift as well.
If you play too slowly the hammer will fail to hit the string and a weak sound, or no sound at all will be produced.
If you play too fast a harsh sound that fails to carry is created. This is due the suddenness of the attack which causes the strings to segment the vibrations rather than allowing the whole length of the string to vibrate, enforcing the fundamental sound.
Children and amateur pianists often make the mistake of believing volume is created by force and will press and push on the keybed. This is a waste of muscular effort and creates an unpleasant tone. As soon as the hammer has struck the string there is nothing we can do to alter the sound other than activating or releasing the dampers. It is important to separate our emotional response to the music from the physical means of tone production.
II. Touch matters
Despite some claims to the contrary, how we physically play the instrument matters. Small changes in alignment and balance can produce large differences in tone production due the way they vary transfer of energy into the key and alter key speed. I’m always astonished how simply unlocking a joint or balancing the finger into a key, a weak, flabby tone can suddenly sound rich and full.
As Thomas Mark notes in his book “What Every Pianist Needs to Know About the Body,”the kinesthetic energy delivered to the string is a function of mass and the velocity of the hammer. But kinesthetic energy fluctuates not with the velocity but with the square of the velocity. Consequently, a change in velocity by a certain percent…will result in a larger change in the kinetic energy delivered to the string. This means that seemingly slight changes in the speed of key descent produce large differences in volume and tone quality.”
At the 1:02:00 mark of this Masterclass, Leon Fleisher suggests to a student playing the opening of Beethoven op. 110 that she play more on the pad of the fingers in order to slow the descent of the key and create a more lyrical sound.
At the 2:20 mark of this Masterclass, Fleisher suggest that the pianist play the opening of Prokofiev’s 6th Sonata on the tips of the fingers in order to create a bright and percussive sound.
III. Arm Weight and Matthay
In order to drop into weighted keys without having to use excessive force, forearm weight is essential. While the weight of the arm does not directly affect the sound, it can indirectly change the tone quality by altering the speed of key descent. For instance, asking the forearm to release more weight into the key can cause the key to descend more slowly and less percussively.
One particularly useful way creating different sounds at the piano used by Tobias Matthay was to think in terms of “arm touch”, “hand touch”, and “finger touch”. We of course use all three in combination when playing (moving any part of the body in insolation is in-coordinate), but by slightly altering the proportions we can create different tonal effects.
This was first shown to me in a lesson with Nina Tichman, an expert in Debussy. I was preparing Book 1 of the Preludes for a performance and played for her “Voiles.” The opening passage depicts a sail fluttering in the wind. She suggested playing the opening third with a weighty “arm” sound to ring in the air, the descending thirds with “finger sounds” to create the light flutter of the sail, and the final gesture with “hand” sounds for the ending gust. Immediately the passage took on three distinct colors and sonorities.
You can see her masterful performance of the work here at 1:03:10.
It can be great fun going through your repertoire and experimenting with different combinations.
IV. Ortmann and Descriptive Imagery
Ortmann recognized that we mostly use visual and tactile imagery to describe sound. In his book, “The Physiological Mechanics of Piano Technique” he dedicates a chapter to unpacking what goes into creating these sound images for the listener. Here is a brief summary:
Image Pitch Intensity Duration Percussion/Noise Technique
- “Sparkling” high moderate to great extremely brief very percussive rapid and short muscular contractions
- “Velvety” varied moderate or little long non-percussive molto legato
- “Crisp” n/a at least moderate short but marked n/a fast key release
- “Bell-like” varied moderate or great short percussive beginning rebound off the key
- “Dry” noise small minimal very percussive marked muscular contraction
- “Brittle” n/a moderate to great variable abrupt/percussive abrupt beginning
- “Singing” n/a moderate long non-percussive gradual drop and release
The sound quality needed in the beginning of Schubert Sonata in Bb D. 960 will not be effective at the opening of Bartok’s “Allegro Barbaro.” Provided we create them in a way that is healthy for our bodies, the greater the range of sounds we can conjure up at the instrument, the more interesting our playing will be.
V. Other variables
The focus of this post has been on altering the tone quality of a single note. But there are many other ways to alter the tonal qualities including use of the damper and una corda pedals, balancing chords, melody vs. accompaniment, musical line, and timing. Some factors like regulation of the instrument and acoustics of the space are out of our control.
What is so remarkable about the piano is the seemingly endless sounds and colors that, with knowledge and imagination, we can draw from it. I hope this post will inspire you to experiment and enjoy all the possibilities that the instrument has to offer.
Please let me know if you enjoyed this post. Questions and comments welcomed!