Exam Flashcards
What is the ratio of a Pythagorean octave?
2:1
What is the ratio of a Pythagorean perfect fifth?
3:2
What is the ratio of a Pythagorean perfect fourth?
4:3
What is the ratio of a Pythagorean whole tone?
9:8
What is the ratio of a Pythagorean semi-tone?
256:243
Pythagorean tuning is based on stacking which interval?
Perfect fifths
Quarter-comma mean tone puts which interval perfectly in tune at the expense of the fifth?
Major third
What is the first part of an amplitude envelope called?
Attack
What is the general speed of sound at room temperature?
343 m/s
What type of nodes will you find at the ends of an open-open pipe?
Pressure nodes
What are the disadvantages of just intonation?
It only works with one fundamental (no modulating) and there are two sizes of whole tone
What is the average frequency range of musical pitch?
30-4000 Hz
What is the Pythagorean comma?
The difference between 7 octaves and 12 pure fifths
Which interval is most commonly made out of tune when tempering?
Fifths
What is the ratio of the fifths in 1/4-comma mean tone?
1.495
What is the “wolf” fifth?
The wolf fifth is the fifth that is most out of tune in 1/4-comma mean tone temperament, called the wolf because it “howls”
How big is a cent?
1/100 of an equally tempered semitone
What is the ratio for the equally tempered semitone?
1.0595
What frequency would the A two octaves below A440 be?
110 Hz
What is a standing wave?
A wave that appears to form a stable displacement pattern on a vibrating string (the first mode of vibration)
Two pitches (one at 440 Hz and one at 442Hz) will beat at what frequency?
2 Hz
The pitches formed by the harmonic series of a string correspond to which tuning system?
Just
How do you find the total displacement pattern of a string?
Add all of the component modes
What does a two-dimensional spectrum show?
Amplitude over frequency
The approximate displacement pattern of a bowed string has what waveform?
A sawtooth wave
What does the body of the violin do?
Radiates and filters the sound
How do you calculate frequency?
Speed/wavelength
What do convex surfaces do to sound?
Scatter the sound outwards
What is it called when sound waves bend around an object in their path?
Diffraction
What is intensity?
The amount of power flowing through a given area
How many times more intense will a sound be at 12m than at 3m distance?
16 (3x4)
How do you double intensity in dB?
double is roughly 3dB
What are room modes?
The frequency bands favoured by a room
What do acoustic clouds do in an auditorium?
Increase intimacy and ensemble
What 3 things contribute to the frequency created by blowing on a sharp edge?
Speed of air flow, sharpness of edge, and angle of airflow
What interval do closed pipes overblow at?
Twelfth
What will a small hole drilled near the middle of a length of pipe do?
Allow the second mode to sound more easily
What type of waveform does a double reed create?
Rectangular
How many slide positions does the trombone have?
7
What is the ratio for a Ptolomaic (or just) semitone?
16:15
What are the four types of natural oscillators?
Springs, strings, air columns, and pendulums
What is a node?
The point of no vibration
What is an antinode?
The point of maximum displacement
What is a period?
The horizontal “distance” of one repetition of a vibration
What is the amplitude?
The vertical “distance” between the peak & trough of a wave, on the y-axis of a waveform diagram
What happens to the amplitude with each successive mode?
The amplitude gets smaller with each mode (A=1/m)
What is a spectrum showing?
Amplitude/Frequency, which frequencies are present and the relative volume of the harmonics
What is decay?
The dampening of sounds over time
What is attack?
How quickly a note reaches its maximum amplitude
What are transients?
The collective of decay, sustain, and attack, which together form the amplitude envelope
What is the function of the strings and the body of a violin?
The string is the sound producer and the body is the sound amplifier/modifier (a filter of sorts)
What is impedence?
The resistance to vibration of a particular material. If equal, all energy is transmitted, instantaneous dampening. If very different, vibration lasts and not as much energy transmitted (because there is energy to return along the string)
What is the Helmholtz resonance?
The fundamental resonance of an enclose space (depends on volume of air and the size of the hole)
What are transverse waves?
Waves that displace perpendicular to the direction of propagation.
What are longitudinal waves?
Waves that displace parallel to the direction of propagation (essentially the elasticity of air)
What is the approximate speed of sound at room temperature?
343 m/s
What causes a sonic boom?
When a plane’s speed crosses the speed of sound, the Doppler effect creates a sonic boom
Are the angle of incidence and the angle of reflection equal to one another?
Yes
What is reflection?
Sound bouncing off of a material, depends on impedence
What is absorption?
Sound being absorbed by a material, usually more absorption with softer materials
What is diffraction?
When a sound bends around a solid object
What is refraction?
A change in medium, such as temperature, that causes a soundwave to bend
What is interference?
Two sound sources at the same frequency, can be either in or out of phase with each other
What is phase?
Phase refers to the degree to which two sounds are in sync
What is reverberation?
Time to decay (less than 60dB), the overall mashup of echoes, depending on the volume of the room, the surface area, and absorption and reflection
What is resonance?
The shape and size of a room (which affects the preferred harmonics of the room)
What is diffusion?
Where the waves are scattered, reduces resonance
What is intimacy?
How close the performer sounds
What is ensemble?
The level of reflection among players in an ensemble, as players bodies create acoustic shadows and impede sounds from reaching those behind them
What is warmth?
The reverberation time at low frequencies
What is brilliance?
The opposite of warmth, reverberation times at higher frequencies
What are the 4 types of pipes?
Open-open (such as a flute), open-closed (such as a clarinet), conical (such as a sax), and mixed (such as a trumpet)
Where are the pressure nodes for lower modes in a trumpet?
In the bell (higher outside)
Where are the pressure antinodes for higher modes in a trumpet?
In the mouthpiece
What is unique about the harmonics in a trumpet?
The pedal tone (fundamental) is missing because it s severely out of tune
What is the pipe shape progression of a trumpet?
Cylinder-cone-flare
What are the three types of idiophones?
Lithophones, made of stones, xylophones, made of wood, and metallophones, made of metal
Are the ends of the bar in an idiophone nodes or antinodes?
antinodes
What is Young’s modulus?
The stiffer a thing is, the higher its frequency
How do the supports for the bars on an idiophone affect the modes?
First mode is promoted, second and third are suppressed (due to forced nodes at the antinode position)
How do you tune the bars of an idiophone?
Filing the ends heightens the pitch, filing underneath lowers the pitch
In idiophones, frequency is proportional to what two other elements?
Rigidity and thickness
In idiophones, frequency is inversely proportional to what two other elements?
Density and length
How do you strike a pitched vibrating plate?
You must first get the plate speaking as it has a slow attack
What shape are the nodes on a bell?
Circular nodal lines, concentric around the center of the bell
