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Musical Instruments. Howard & Angus, Chapter 4 www.phys.unsw.edu.au. Any acoustic instrument has two main components: a sound source, and sound modifiers. e.g., echo, reflection, absorption. Student project. Student project. Hearing music in different environments. Stringed instruments.
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Musical Instruments Howard & Angus, Chapter 4 www.phys.unsw.edu.au
Any acoustic instrument has two main components: • a sound source, and • sound modifiers. e.g., echo, reflection, absorption Student project
Student project Hearing music in different environments
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
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. bridge variable mass
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.
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.)
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.
Example: Violin family • top plate ( the plate under the string which the bridge stands on and which has the fholes) • back plate • the air contained within the main body of the instrument • Less: • glues, varnish, choice of wood, wood treatment
The main parts of flue (open metal and stopped wood) and reed organ pipes
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.
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
Recorder and flute • The length of the resonator is changed by means of finger holes. • To play a second octave the flue is overblown.
Brass instruments The sound source in brass instruments is the vibrating lips of the player in the mouthpiece
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
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)
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.
Student Project A truly psychological question: Musicians and instruments: Are there any personality characteristics? or Are trombone players different from violinists?