vocab

Question 1

acoustics

Answer 1

branch of physics; the study of physical properties of sound and how sound is generated and propogated

Question 2

psychoacoustics

Answer 2

study of how humans respond to sound as a physical phenomenon; it is a branch of both psychology and acoustics

Question 3

sound

Answer 3

physically: result of vibration or disturbance in the molecules of a medium;
psychologically: vibration or distrurbance in the air that is potentially audible, although instruments can measure inaudible sound

Question 4

sound waves

Answer 4

movements of particles in a medium containing expansions and contractions of molecules

Question 5

compression or condensation

Answer 5

phase of sound in which vibratory movements of an object increase the density of air molecules bc the molecules are compressed or condensed; opposite of rarefaction

Question 6

rarefaction

Answer 6

the thinning of air molecules when vibrating object returns to equilibrium; opposite of condensation/compression

Question 7

simple harmonic motion

Answer 7

back and forth movement of particles when the movement is symmetrical and periodic; also known as sine wave

Question 8

siusoidal wave

Answer 8

wave w/ horizontal and vertical symmetry bc it contains one peak and one valley; contains a single frequency and is the result of simple harmonic motion

Question 9

aperiodic wave

Answer 9

waves that do not repeat themselves at regular intervals; their vibratory patterns are random and difficult to predict from one time interval to the next

Question 10

period wave

Answer 10

sound waves that repeat themselves at regular intervals and are predictable

Question 11

amplitude

Answer 11

magnitude and direction of displacement; in acoustics, it is the strength or magnitude of a sound signal; the greater the amplitude, the louder the sound signal

Question 12

intensity

Answer 12

quality of sound that creates the sensation of loudness; physically, intensity is the amount of energy transmitted per second over an area of 1 square meter. it is measured in terms of watts per square meter and is also expressed in decibels

Question 13

bel

Answer 13

logartihmic unit of measure of sound intensity. it is a basic and relative reference measure that helps express the wide range of sound intensities to which the human ear is sensitive by means of a compressed, logarithmic scale

Question 14

decibel

Answer 14

measure of sound intensity that equals one tenth of a bel

Question 15

CSG system

Answer 15

metric system of measuring length in centimeters, time in seconds, and mass in grams; it can be contrasted w/ the MKS system.

Question 16

MKS system

Answer 16

metric system of measuring length in meters, mass in kilograms, and time in seconds

Question 17

dyne

Answer 17

measure of force in the CSG metric system; 1 dyne is the force required to accelerate a mass of 1 gram from a velocity of 0 cm per second to a velocity of 1 cm per second

Question 18

density

Answer 18

around of mass per unit volume; serves as a medium for sound and affects sound transmission

Question 19

displacement

Answer 19

change in position; air molecules are said to be displaces b/c of the vibratory acceleration of an object

Question 20

oscillation

Answer 20

back and forth movement of air molecules b/c of a vibrating object

Question 21

force

Answer 21

vector quantity that tends to produce an acceleration of a body in the direction of its application; it is also defined as the produce of mass and acceleration

Question 22

elasticity

Answer 22

property that makes it possible for matter to recover form and volume when subjected to distortion

Question 23

velocity

Answer 23

change in position of, for example, air molecules when an object is set into vibration; is measured in terms of distance an object moves per time and direction it takes to move

Question 24

frequency

Answer 24

one of the two characteristics of vibratory motion; it is the rate of vibratory motion that is measured in terms of the number of cycles per second; Hz. Hertz is the unit of measure of 1 cycle per second

Question 25

natural frequency

Answer 25

frequency w/ which a source of sound normally vibrates; it is determined by the sources mass and stiffness. mass is the quantity of matter and is not to be confused w/ eight, which is gravitational force exerted on mass. the mass of a medium of sound affects its transmission. increased mass results in decreased frequency, and increased stiffness results in increased frequency

Question 26

formant frequency

Answer 26

frequency region w/ concentrated acoustic energy. it is the center frequency of a formant, which is resonance

Question 27

fundamental frequency

Answer 27

lowest frequency of a periodic wave; it is the first harmonic

Question 28

octave

Answer 28

indication of the interval b/w two frequencies. intervals always maintain a ration of 1:2, thus, each octave doubles a particular frequency; ex/ 200 Hz is 1 octave above 100 Hz, and 2000 is 1 octave above 1000 Hz

Question 29

impedance

Answer 29

acoustic, mechanical, or electrical resistance to motion or sound transmission

Question 30

newtons law of motion

Answer 30

sound involves motion; law of inertia: all bodies remain at rest or in a state of uniform motion unless another force acts in opposition. in other words, a body in motion tends to remain in motion and a body at rest tends to stay at rest. the law of reaction forces says that every force is associated w/ a reaction force of opposite direction

Question 31

pressure

Answer 31

around of force per unit area; measured either as dynes or newtons and is important in understanding the amount of pressure that sound waves exert on the eardrum

Question 32

reflection

Answer 32

phenomenon of sound waves traveling back after hitting an obstacle, with no change in the speed of propagation

Question 33

refraction

Answer 33

bending of the sound wave due to change in its speech of propogation; this happens, for example, when sound waves move from one medium to another (air to water)

Question 34

resonance

Answer 34

modification of sound by other sources; in speech acoustics, resonance refers to modification of the laryngeal tone predominantly by the nasal and oral cavities

Question 35

transmitting medium

Answer 35

any matter that carries or transmits sound. air liquids and solids can all transmit sound; the mass and elasticity of transmitting medium affect sound