Speech Science: Basic Definitions

acoustic

a branch of physics, is the study of the physical properties of sound and how sound is generated and propagated

psychoacoustic

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

sound

it is the result of vibration or disturbance in the air or it is an audible variation or disturbance in the air

compression or condensation

is a phase of sound in which the vibratory movement of an object (tuning fork) INCREASE the DENSITY of air molecules because the molecules are compressed or condensed. It is the opposite of rarefratction.

Rarefraction

is the thinning of air molecules when the vibrating object returns to equilibrium; it is the opposite of condensation

simple harmonic motion

refers to the back-and-forth movement of particles when the movement is SYMMETRICAL and PERIODIC, it is also known as SINE WAVE

Sinusoidal motion or wave

is a wave with HORIZONTAL and VERTICAL SYMMETRY because it contains one peak or crest and one valley or trough; it contains a SINGELE FREQUENCY; it is a result of simple harmonic motion

aperiodic waves

are those that DO NOT REPEAT themeselves at regular intervals; their vibratory patterns are random and difficult to predict from one tme interval to the next

periodic wave

sound waves that REPEAT themselves at regular intervals

amplitude

is one of two characteristics of vibratory motion and is the MAGNITUDE and DISPLACEMENT. In acoustics, it's the strength or magnitude of a sound signal; the GREATER the AMPLITUDE the LOUDER the SOUND SIGNAL

Intensity

is the quality of sound that creates the SENSATION of LOUDNESS ; physically, intensity is the amoutn of energy transmitted per second over an area of one square meter; it is measured in terms of watt per square meter; it is also expressed in DECIBELS

Bel

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

Decibel dB

is a measure of sound intensity; it equals one tenth of a bel

csg system

is a metric system of measuring length in centimeters , time in seconds and mass in grams, it can be contrasted with the MKS this system measures length in meters and mass in kilograms and time in seconds

dyne

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

density

is the amount of mass per unit volume. It is the matter that serves as a medium for sound affects sound transmission

displacement

is a change in position; air molecules are said to be displaced because of the vibratory action of an object

oscillation

refers to the to-and -from movement of the air molecules becasue of a vibrating object

force

is a vector quantity that tends to produce an acceleration of a body in the direction of its application; it is also defined as the product of mass and acceleration. it is measured in terms of Nt (Newton) 1 newton equals the force required to accelerate a

elasticity

is a property that makes it posible for matter (helps transmit sound) to recover its form and volume when subjected to distortion; all matter is subjected to distortion when force is applied to it

velocity

is a CHANGE in POSITION; ex. air molecules when an object is set to vibration velocity is measured in terms of distance an object moves per the time and the direction it takes to move

frequency

is one of the two characteristics of vibratory motion and is the RATE of vibratory motionthat is measured in terms of NUMBER OF CYCLES COMPLETED PER SECOND OR IN TERMS OF HZ

Hertz

is the unit of measure of frequency 1 cycle per second is 1 HZ

natural frequency

is the frequency with which a source of sound normally vibrates. It is determined by the source's mass and stiffness

mass

is the quantity of matter, adn is not to be confused with weight the mass of a medium of sound affects its transmission. INCREASED mass = DECREASED frequency
INCREASED STIFFNESS = INCREASED FREQUENCY

formant frequency

is a frequency region with conentrated acoustic enery; it si the center of frequency of a formant, which is RESONANCE

Fundamental frequency

is the LOWEST FREQUENCY of a PERIODIC WAVE. It is the FIRST HARMONIC

octave

is an indication of the interval between two frequencies the intervals always maintain a ratio of 1;2, each octave DOUBLES apraticular frequency (ex. 200 Hz is one octave of 100 Hz, and 2, 000 Hz is one octave above 1,000 Hz)`

impedance

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

Newton's Law of Motion

explain motion and its characeteristics. Sound involves motion; the law of inertia states that all bodies reamin at rest or ina state of uniform motion unless another force acts in opposition. in other words, a body in motion tends to treamin in moiton an

pressure

is the amount of force per unit area. Force is measured eithea s dynes or as newtons and is important in understanding the amount of force sound waves exert on the eardrum

reflection

refers to the phenomenon of sound waves traveling back after hitting an obstacle with no change in the speed of propagation, this happens for ex when sound waves move from one medium (air) to another (water)

resonance

is the modifiaiton of sound by other sources; speech acoustics, it refers to the modifcation of the laryngeal tone predominantly by the nasal and oral cavities

transmitting medium

is any matter that carries or transmits sound, air, liquids, and solids can all transmit sound; MASS AND ELASTICITY media affect sound