A.Diederich – International University Bremen – USC – MMM – Spring 2005

Musical Instruments

Howard & Angus, Chapter 4

www.phys.unsw.edu.au

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Any acoustic instrument has two main components: a sound source, and sound modifiers.

e.g., echo, reflection, absorption Student project

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Student project

Hearing music in different environments

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Stringed instruments

The string family of musical instruments includes the

violin, viola, violoncello, double bass and all their predecessors

keyboard instruments use of strings, such as the piano, harpsichord, clavichord and spinet

A.Diederich – International University Bremen – USC – MMM – Spring 2005

All stringed instruments consist of one or more strings stretched between two points.

The fundamental frequency produced by the string is dependent on its mass per unit length, length and tension.

The mass per unit length of an individual string is constant and changes are made to the tension and/or length to enable different notes to be played.

bridgevariable mass

A.Diederich – International University Bremen – USC – MMM – Spring 2005

The string is set into vibration to provide the sound source to the instrument.

A vibrating string on its own is extremely quiet because …?

All practical stringed instruments have a body which is set motion by the vibrations of the string(s) of the instrument.

The body of the instrument is the sound modifier.

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Three main methods by which energy is provided to a stringed instrument:

plucked (e.g., violin family, guitar lute) bowed (e.g., violin family) struck (e.g., piano)

(A vibrating string fixed at both ends has a unique set of standing waves.)

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Sound modifiers in stringed instruments

The sound source provided by a plucked of bowed string is coupled to the sound modifiers of the instrument via a bridge.

The vibrational properties of all elements of the body of the instrument play a part in determining the sound modification that takes place.

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Example: Violin family

top plate ( the plate under the string which the bridge stands on and which has the f holes)

back plate the air contained within the main body of the

instrument Less: glues, varnish, choice of wood, wood

treatment

A.Diederich – International University Bremen – USC – MMM – Spring 2005

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Wind instruments

A.Diederich – International University Bremen – USC – MMM – Spring 2005

The main parts of flue (open metal and stopped wood) and reed organ pipes

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Sound source in organ flue pipes

The important features of a flue sound source are a narrow slit (the flue) through which air flows, and a wedge-shaped obstacle placed in the airstream from the slit.

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Sound modifiers in organ pipes

The sound modifier in a flue organ pipe is the main body of the pipe itself, or its "resonator".

The most straightforward are resonators whose dimensions do not vary along their length.

Two basic types: open or stopped at the end The fundamental frequency of air reed

vibration is entirely controlled by: the length of the resonator whether the pipe is open or stopped

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Recorder and flute

The length of the resonator is changed by means of finger holes.

To play a second octave the flue is overblown.

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Brass instruments

The sound source in brass instruments is the vibrating

lips of the player in the mouthpiece

A.Diederich – International University Bremen – USC – MMM – Spring 2005

The basic valve combinations used on brass instruments to enable seven semitones to be fingered.

Black circle = valve depresses White circle = valve not depressed On a trumpet, first valve is nearest the mouthpiece, second in

the middle, and third nearest the bell

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Percussion instruments

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Sound source and sound modifiers

The sound source in percussion instruments usually involves some kind of striking. (Impulse, all frequency components, non-periodic)

Three classes of percussion instruments, using bars (e.g., xylophone, glockenspiel, céleste,

triangle) membranes (e.g., drums) plates (e.g., cymbals)

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Two categories regarding pitch

Those with a definite pitch, on which a melody can be played.

Those with an indefinite pitch, on which a melody cannot be played.

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Definite Pitch Indefinite Pitch

Timpani                   Bass Drum

Celesta  Side Drum

Xylophone Cymbal

Glockenspiel  Gong

Tubular Bells      Triangle

Tambourine

Castanets

Wooden Block

A.Diederich – International University Bremen – USC – MMM – Spring 2005

A.Diederich – International University Bremen – USC – MMM – Spring 2005

Student Project

A truly psychological question:

Musicians and instruments: Are there any personality characteristics? or

Are trombone players different from violinists?