The further, harder and faster that a string is pluck/struck/bowed, the louder and more overtone-rich the sound. 

A sound is louder and overtone-richer if:

  • – A plectrum pulls the string hard and far 
  • – A hammer hits the string fast and hard
  • – Bow speed and bow pressure are high. However, the situation for bowing is more complicated. Cello map link

Very high excitation force causes detuning and pitch bends

Eventually the sound does not become louder or overtone-richer by plucking, striking and bowing at very high forces; instead, a detuning effect is heard. The tone is sharp at first and falls to its normal frequency as the sound decays, causing a downward pitch bend.  This is especially noticeable for the plucked string because the decay is usually relatively long.  The effect is greater on the lower strings.

The stopped C string is plucked so hard that it vibrates at a sharper pitch.  A downward pitch bend is heard as the vibration decays.


For the bowed string, a downward pitch bend is produced by increasing bow pressure.  Because it is possible to change bow pressure during a stroke, a detuning followed by a return to normal pitch is possible within a single stroke.

A downward pitch bend is controlled by increasing bow pressure.  The pitch returns to normal as the pressure decreases



Pitch bends are easier to produce for harmonics, especially lower order harmonics; high harmonics are less stable under bow pressure changes.

Downward pitch bends in harmonics by increasing bow pressure

Very low excitation force causes overtone-takeover 

Under very low plucking/striking/bowing force, higher partials are more present than the fundamental; the first few overtones dominate the sound.  In this case, the excitation force is so low that the overtone-takeover point is moved into the region of the ‘normal’ contact point. Cello map link.See above for more info and video.


Bartók or snap pizzicato 

Plucking a string with high force often results in Bartók or snap pizzicato.  The quality of the ‘snap’ and the normal pizzicato sound depend on contact points and plucking directions. Cello map link


Increasing/decreasing striking force changes the balance between piano- and clavichord-type battuto

Both types of battuto get louder as striking force increases.  

  • – For light to moderate striking forces, increases in the loudness of piano-type vibrations are more apparent than clavichord-type.  
  • – For large striking forces, increases in the loudness of clavichord-type vibration are more apparent than piano-type. 

Light to moderate striking forces:

For a light striking force, clavichord-type can be as loud as piano-type pitches; however, with increasing force the loudness of the latter quickly overtakes the former.  Under moderate striking forces, piano-type vibrations are usually louder than the clavichord-type.  

A ‘scale’ of striking force from very light to moderate.  An open string is struck four times with a very light force, four times with a light force and four times with a moderate force.  The piano-type pitch becomes more and more dominant.

The only case in which this is not true is for short lengths of string, where damping effects at the stopping finger reduce the amplitude of the piano-type tone significantly and the hammer-to-bridge clavichord-type tone can be well heard.

Striking force is less significant for short lengths of string.  A stopped string is struck four times with a very light force, four times with a light force and four times with a moderate force.  The piano-type pitch is relatively weak; it gets louder with higher force, but does not dominate the hammer-bridge clavichord pitch. 

High forces:

The duration of contact between string and hammer is an important factor in battuto sound and it increases with striking force.  As contact time between hammer and string increases, clavichord-type battuto become louder and longer and piano-type battuto become quieter and decay faster.

Scale of striking force from moderate to very high force.  An open string is struck four times with moderate force, four times with a relatively high force, and four times with a very high force.  The clavichord tones become more dominant as the force increases.  A slight upward shift in pitch is also heard.

You can control contact time between bow and string by changing the impact point of the bow.Contact time can be easily controlled independently of striking force.  For example, striking the string with different points of the bow:  
– If the middle of the bow strikes the string, the bow naturally ‘jumps’ away from the string quickly after impact
– If the frog of the bow strikes the string, the bow stays in contact with the string for a longer time
-If the hammer is held down on the string after striking there is no/almost no output from piano-type vibration.

The bow is held to the string until the excitation energy is used up.  Only clavichord-type pitches are heard


Clavichord-like pitch bends

Pitch bends occur with high striking force.  They can be controlled for clavichord-type pitches to produce a ‘vibrato’ effect (like the vibrato effect in a clavichord) by applying a pulsating force with the hammer after it has struck the string (maintaining contact between hammer and string).  This is more effective when a dense hammer is used (e.g., a knife).

A vibrato effect for clavichord battuto

A longer, more effective vibrato effect is possible for dense hammers (in the video I use a knife) and on longer lengths of string (in the video, the vibrato on the lower clavichord pitch is almost always more prominent).


The relationship between bow pressure and bow speed

Bow speed, bow pressure and contact point are interdependent.  If a cellist changes one factor (e.g., increases bow pressure), the bowing conditions will change, and the other factors will, relatively, also change.  

Controlling relative bow pressure, speed and point of contact becomes instinctive to cellists.  For example, for an increase in bow pressure, a constant sound quality and loudness is only maintained by reducing bow speed and/or by moving contact point away from the string’s mid point.  Some overpressure techniques require a desynchronising of well-practiced methods.  

Very low bow pressure

At very low pressures, timbre has a thin quality: flautando or flautato.  Both the fundamental and the high partials are weak.  Flautando sul ponticello brings out some upper partials.  Cello map link Bowing at low pressure with a fast bow stroke is shown in this video link to video 

Very high bow pressure

Extreme increases in bowing pressure can be controlled to produce distorted sounds, low pitches and clicking sounds.  The controlling factor is the relationship between bow pressure and bow speed. 

Distorted noise

Distortion-like sounds are produced by ‘desynchronising’ bow speed and pressure (i.e., by using bow speeds above or below the normal range for a particular high bow pressure).  High-pitched squeaking sounds might also be present alongside clicking sounds and/or undertones (see below).  Loudness is controlled by bow speed; relatively quiet distortion sounds are easily producible under slow bow strokes.  Contact point can change the sound significantly.

Distortion sounds by playing with high bow pressure.  The sounds are played with a fast and then slow bow stroke, sul ponticello and sul tasto.


Undertones (or subharmonics) are pitches below the fundamental frequency of a string.  The pitch is usually a minor seventh below the fundamental but can vary. Several different pitches might be possible.  Undertones require high bow pressure and a very consistent bow speed at the lower end of ‘normal’ playing.  In general they are easier to produce when the point of contact is not very close to the bridge.  It is very difficult to sustain the tone, which often has a high noise component. There has been some research into violin undertones by Mari Kimura. Bibliography link Moving the point of contact towards the bridge sharpens the pitch slightly but also makes the tone less stable.

Undertones on each string.  At first, a short tone is played with normal pressure to show the fundamental pitch.

Clicking Sounds/Nageln

Bowing under very high pressure and with very slow strokes produces a ‘clicking’ sound with either one or two clear pitches.  The speed of the individual ‘clicks’ is controlled by bow speed.  Long pauses between the clicks can be controlled more easily when the right hand thumb presses against the fingerboard as a pivot.  The two possible pitches are dependent on point of contact, being determined by the length of string between bridge-edge of bow and bridge and between nut-edge of bow and nut.  Damping or stopping the string on either side of the bow isolates one of these pitches.  It is easier to produce a consistent effect when the bow is held in the fist of the right hand or if the first finger of the right hand is extended along the length of the bow.  The technique is stabilised when the cellist pulls the string upwards, towards the bow with the left hand.  This necessarily dampens one of the component pitches.

Some examples of nageln/clicking sounds.  The right-hand thumb is used as a pivot to stabilise the hand. The technique is shown on each string.  I show a variety of sounds, by damping the string on either side of the bow and by damping the other strings or letting them ring. 


Controlling volume is difficult for high-pressure techniques

Variations in volume for undertones and clicking sounds are restricted because the bow pressure and speed are fixed within a narrow range.  For undertones, where the technique is most dependent on the relationship between bow pressure and speed, volume is virtually fixed and uncontrollable.

In general, overpressure effects are easier to produce on shorter, thicker vibrating strings.  In other words, a more extreme, more easily controlled overpressure effects are possible in high positions on the low strings. 


Nageln sounds similar to high-pressure vertical bowing.  The pitch content is, however, different because in the former case the string is vibrating and, in the latter case, the bow. 

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