2. Physiological and Acoustic Phonetics: A Speech Science Foundation Flashcards
Pitch
- Auditory sensation (i.e., perception) of the frequency with which the VFs vibrate, whereas frequency is a physical property of the actual sound waves
- Determined by mass, tension, and elasticity of the VFs
- Can affect meaning (e.g., statement vs question)
Intensity
- Intensity is sound pressure
- Sensory correlate of intensity is loudness/volume
- Loudness is related to amplitude
Juncture
“Vocal punctuation”
- Combination of suprasegmentals (e.g., intonation and pausing)
- E.g., “What did you eat?” vs “What, did you eat?”; “I scream” vs “Ice cream”
Acoustics: Basic Definitions
Sound Waves
Movements of particles in a medium containing expansions and contractions of molecules; Waves can be periodic or aperiodic
Compression (aka Condensation)
Compression/condensation: a phase of sound in which the vibratory movements of an object (e.g., the tines of a tuning fork) increase the density of air molecules b/c the molecules are compressed or condensed; Opposite of rarefaction
Rarefaction
Thinning of air molecules when the vibrating object returns to equilibrium; Opposite of condensation
Simple Harmonic Motion
Back-and-forth movement of particles when the movement is symmetrical and periodic; Aka a sine wave
Sinusoidal Motion/Wave
A wave with horizontal and vertical symmetry b/c it contains one peak/crest and one valley/trough; Contains a single frequency and is a result of simple harmonic motion
Amplitude
Amplitude is 1 of 2 characteristics of vibratory motion and is the magnitude and direction of displacement; In acoustics, it is the strength and magnitude of a sound signal (the greater the amplitude, the louder the sound signal)
Intensity
Quality of sound that creates the sensation of loudness; Physically, intensity is the amount of energy transmitted per second over an area of one square meter; Measured in terms of watts per square meter and is also expressed in decibels (dB)
Frequency
Frequency is 1 of 2 characteristics of vibratory motion; It is the rate of vibratory motion that is measured in terms of the number of cycles completed per second or, more recently, in terms of hertz (Hz)
Natural Frequency
Frequency with which a source of sound normally vibrates; Determined by the source’s mass (quantity of matter) and stiffness
Increased mass results in decreased frequency, and increased stiffness results in increased frequency
Formant Frequency and
Fundamental Frequency
Formant frequency: A frequency region with concentrated acoustic energy; It is the center frequency of a formant, which is a resonance
Fundamental frequency: lowest frequency of a periodic wave; It is the first harmonic
Octave
Indication of the interval between two frequencies; The intervals always maintain a ratio of 1:2; thus, each octave doubles a particular frequency (e.g., 200 Hz is one octave above 100 Hz)
Impedance
Acoustic, mechanical, or electrical resistance to motion or sound transmission
Newton’s Law of Motion
Explains motion and its characteristics. Basically, sound involves motion. The law of inertia states that all bodies remain at rest or in a state of uniform motion unless another force acts in opposition. I.e., a body in motion tends to stay in motion and a body at rest tends to stay at rest. The law of reaction forces says that every force is associated with a reaction force of opposite direction
(Sound) Pressure
Pressure is the amount of force per unit area
Force is measured either as dynes or as newtons and is important in understanding the amount of force sound waves exert on the eardrum
Sound Wave Generation and Propagation
The 2 Main Properties of a Medium That Affect the Transmission of Sound
Mass (density) and Elasticity
*A more elastic medium (even if it is more dense) will propagate sound faster than a less elastic (even if it is less dense) medium (e.g., steel>air)
Velocity
The amount of molecular displacement per unit of time is measured in terms of velocity ; A change in velocity is described as acceleration or deceleration; Acceleration is also related to direction of movement (when direction changes, velocity also changes)
Frequency and Pitch: The normal ear of a young adult can respond to __ Hz to ___ Hz.
20 Hz to 20,000 Hz
Human ear is more sensitive to changes in lower frequencies (below 1,000 Hz) vs higher frequencies
Intensity of normal conversational speech
Varies between 50 and 70 dB SPL
very intense sounds exceed 100 dB SPL and may induce pain
