Speech Science

LEC 1 + 2

helium

airflow changes acoustic output and frequency leading to increased frequency than normal

sinewave speech

synthesizer; machine creates speech signal, not perfect

(used to create vocal harmonics and simulate speech sounds through varying frequencies.)

cochlear implants

speech is filtered, doesnt sound clear, frequencies

problems with speech:

1) segmentation

2) streaming

3) lack of invariance

segmentation

speech is continuous even if it’s perceived as discrete (like if ur hearing a foreign lang and cant tell where one word starts/ends without breaks)

streaming

hearing listeners can separate sounds easily (relevant sounds vs background noise)

lack of invariance

acoustic signal does not always show exact same patterns for two perceptually identical segments (same word/sound does not always sound the same even if said the same way)

(speakers differ from each other; coarticulation: the articulation of speech sounds are affected by other sounds near them)

movement made audible

speech is nothing but change of pressure in the air

speech is

tangible/concrete (can be measured/manipulated due to acoustic output; strings of sounds reflect movement of articulators)

3 major areas of study

1) physiologic arena/articulatory phonetics

2) acoustic arena/acoustic speech

3) perceptual arena/speech perception

measurement in clinical evaluations

Qualitative: pitch, loudness, roughness

quantitative: fundamental frequency, amplitude

no mass/weight

sound has no mass/weight

something needs to

vibrate for something to happen

longitudinal wave

sound travels in a longitidunal wave

movement made visible

speech is movement made visible

force

push/pull (displacement/restorative); measured by effect upon an object

newton 1st law of motion (law of inertia)

object at rest stays at rest, object in motion stays in motion (change in motion is not the same as no motion)

2 things needed to vibrate

inertia, elasticity

inertia

tendency for mass at rest to remain at rest

elasticity

ability to spring back after deformation (all solids are elastic; gases also behave like it)

friction

impedes/opposes movement

newtons 3rd law of motion

for every action (force) there exists an equal or opposite reaction (air molecules hitting another)

solid

holds shape + volume

liquid

maintains volume, takes shape of container

gas

does not retain shape or volume

(molecules in gas collide with each other)

density

amount of material packed in given volume

density equals

mass/volume (not weight but state)

_ volume _ density

larger volume lower density; lower volume larger density

pressure

force exerted by collision of molecules with each other and the wall of the container

_ volume _ pressure

higher volume lower pressure; higher pressure lower volume

maximum point of displacement

as far as they can go

inertia and elasticity have

inertia and elasticity have inverse relationship

period

time to complete 1 cycle (every cycle same time)

ex: 5 secs for 1 cycle so then 2nd cycle is also 5s ecs

amplitude

depends on amount of force used to start movement (strong push makes swing go further)

what travels forward? molecule or wave?

disturbance (wave) travels forward not the molecule/particle

waves

disturbance composed of vibration

medium

interconnected particles

compression

increased pressure

rarefaction

decreased pressure

longitudanal wave

movement of particle is parallel to movement of wave

transverse wave

movement of particle is perpendicular to movement of wave

Simple Harmonic Motion

pure tone (one frequency)

Frequency

cycles per sec Fo

cycle

one alternating compression + rarefaction

period and frequency

period and frequency are inversely related

mathematically

Freq= 1/period Period= 1/freq

ex: if freq= 20Hz then period is 1/20th of a second

if freq= 200Hz then period is 1/200th of a second

the higher the frequency the ___ the period

shorter

the lower the frequency the ___ the period

longer