Speech & Hearing Final

Front 1

Voltage

Back 1

-How much energy the current carries.
-Electric potential is like water pressure or water height.
-Units: Volt (V) or millivolt (mV)

Front 2

Current

Back 2

-How many electrons move past a point per second.
-Units: Ampere (A, Amp) or milliampere (mA).

Front 3

Power

Back 3

-Total energy flow.
-Quantity x Potential (P=IV)
-Unit: Watt (W)

Front 4

Resistance

Back 4

-How hard it is for electrons to force their way through the device.
-Resistance is like a water flow constriction.
-Units: Ohm, kiloohm, or megaohm.

Front 5

Impedance

Back 5

-The resistance to alternating current (AC).
-Units: Ohm (same as resistance).

Front 6

RMS

Back 6

-71% of the amplitude?
-RMS= "root mean square"
-The square root of the average of the square of the voltage.
-All AC currents and voltages are RMS unless otherwise stated.

Front 7

VU

Back 7

?

Front 8

AC

Back 8

-Alternating current.
-Direction keeps changing.
-Push--Pull. >>><<<

Front 9

DC

Back 9

-Direct current.
-Always flows in the same direction.
>>>>

Front 10

Impedance Matching

Back 10

-Amplifier output impedence must be very close to the speaker impedance (usually 8 ohms).
-Microphone output impedance must be very close to the pre-amp input impedance. (more variable: 600 ohms low, 50 kiloohms high).
-Otherwise, weak signal output, might damage amplifier.

Front 11

Gain

Back 11

-Amplification: Using a small signal to control the output of a big power source.
-Transistors act like a valve or a gate.
-A little current is controlling a BIG current source.
-Effect is to multiply the input voltage and/or current.
-Called the gain of the amplifier.
-Can be 100-1000
-Symbol: triangle l>--

Front 12

Equalization

Back 12

?

Front 13

Microphone types and directionality terms

Back 13

?

Front 14

usable dynamic range of magnetic media

Back 14

only 50 dB

Front 15

Analog

Back 15

Continuously variable signal (i.e., sound).

Front 16

Digital

Back 16

-Represents something as a number.
-Typically a binary number: 1's and 0's (on and off).
-Much easier for electronics than 0-9 (decimal) numbers.

Front 17

Advantages/Disadvantages of Digital

Back 17

?

Front 18

DSP

Back 18

-Digital signal processor.
-Specialized...(more notes)

Front 19

ADC

Back 19

-Digital sampling.
-ADC: Analog to Digital Converter.
-The changing amplitude of the wave is converted to a series of numbers.

Front 20

DAC

Back 20

-Digital playback.
-DAC: Digital to Analog Converter.
-Analog wave is reconstructed by turning a series of numbers back into a changing amplitude.

Front 21

SNR

Back 21

-signal to noise ratio
-s/n

Front 22

Nyquist frequency

Back 22

Highest frequency in the signal.

Front 23

Quantization error

Back 23

Imperfect conversion (A-D and D-A).

Front 24

Sample rates and bits used for CD recording

Back 24

?

Front 25

Diphone

Back 25

-A speech segment that extends from the middle of one phoneme into another.
-"acoustic segments"
-40 phonemes in English, ~1600 diphones.

Front 26

Speech to text algorithm (very general)

Back 26

-Sample ~100 times/second (faster not better).
-Analyze spectrum into ~30 parameters.
-Pattern matching.
-Template for isolated words.
-Best match for the series of “states” associated with each word.
-Train for individual voices.
-Work on the diphone level.
-Use dictionary to associate speech units with words.
-Use grammar/context to judge homonyms.

Front 27

Parsing

Back 27

Analysis of the syntax.

Front 28

Spliced Speech

Back 28

-Record numbers, letters, and phrases. Plays them back by piecing them together.
-First used for directory assistance. Now used for banks, airlines, for automated phone services...

Front 29

Text to Speech Algorithm (Very General)

Back 29

-Pronouncing dictionary.
-Phonetic translation, syllable boundaries and stress, part of speech.
-Parsing (analysis of the syntax) of the text input.
-Determine stress and intonation.
-Retrieve diphones and merge.
-Fine-tune duration, frequency to achieve intonation.
-Control sound generator hardware.
-Still a ways to go yet…

Front 30

Fast Fourier Transform (definition)

Back 30

-Spectrum analysis.
-Converts a signal that is changing over time...into its frequency components.
-"Breaks the signal into its component frequencies."

Front 31

HMM

Back 31

-Hidden Markov Models for statistical analysis.
-Best match for the series of "states" associated with each word.
-Train for individual voices.
-Work on the diphone level.

Front 32

Lossy Compression

Back 32

-Can NOT recover the complete signal when decompressing later.

Front 33

Advantage of MP3 over CD

Back 33

?

Front 34

Key points on "perspectives on therapy" (last class).

Back 34

?

Front 35

Key points from "what is science" lecture (first class).

Back 35

?

Front 36

The +3, +5, +6 dB rule as the number of identical intensity sources are added.

Back 36

+3: double
+5: triple
+6: four times

Front 37

The rationales for the frequency dependence in our threshold of hearing:

Back 37

-Particularly sensitive to certain frequencies because of our ear canal (tiny closed tube) that resonates at those frequencies (3-4 kHz).
-Not sensitive to others because they are the frequencies that the sounds of our organs resonate at.

Front 38

What dB level is a conversation? A noisy room? A quiet place?

Back 38

-Conversation: 60 dB
-A noisy room: greater than 75 dB
-A quiet place: below 40 dB

Front 39

Basic OSHA noise exposure guidelines.

Back 39

?

Front 40

The properties of intelligible speech (intensity levels, frequency ranges, sensitivity to noise).

Back 40

60 dB

Front 41

Vocal folds during vocalization and phonation.

Back 41

Vocal cords close immediately prior to phonation (voice production). Air pressure below vocal cords due to air from lungs. Vocal cords separate briefly with release of air. Vocal cords re-approximate. Vocal cords come together again.

Front 42

Myoelastic Aerodynamic Theory of Phonation

Back 42

-muscles regulate thickness and tension of folds, hence their fundamental frequency.

Front 43

Bernoulli Effect

Back 43

-Flowing air exerts less pressure than still air.
-(Why they close...) Air flowing past the folds drops in pressure. Folds are under muscle tension and can now be pulled shut. This stops the air flow, increasing pressure and causing them to push apart again. Rate of vibration is controlled by muscle tension.

Front 44

What are the vocal cords?

Back 44

-finely tuned neuromuscular units that adjust pitch and tone by altering their position and tension.

Front 45

Vocal Cord Positions:
Abducted?
Adducted?

Back 45

-Abducted: open, separated, relaxed position.
-Adducted: closed, brought together for voicing.

Front 46

Intensity JND

Back 46

-loudness difference
-average person can just tell JND at 1 dB...about 25%

Front 47

Frequency JND

Back 47

-just noticeable difference in two tones
-average person has an average .5% frequency change.

Front 48

Phon

Back 48

-unit of perceived loudness
-comparison between air power/heard power over a range of frequencies...all in reference to a 1 kHz base.

Front 49

Sone

Back 49

-unit of equal loudness
-subjective judgment...what sound "twice as loud".
-1 Son=40 phons at 1 kHz.

Front 50

Formant

Back 50

A specific frequency region wherein any harmonics are emphasized by the resonant qualities of the vocal tract.

Front 51

Overtone

Back 51

Any frequency higher than the fundamental.

Front 52

Harmonic

Back 52

Frequency that is a multiple of the fundamental.

Front 53

Hearing Level

Back 53

-Hearing Level (dBHL) is an individual's threshold of hearing (in dB) relative to a standard (typically the 0 phon level).
-Are hearing impaired if HL is shifted over 25 dB in the critical 500-2,000 Hz speech region.

Front 54

Threshold of pain

Back 54

120 phons

Front 55

Slight Hearing Loss

Back 55

16-25 dB HL loss.
-Need to ask people to repeat themselves, miss some of the softer phonemes.

Front 56

Mild Hearing Loss

Back 56

26-40 dB HL loss.
-Hear normal conversation as a whisper.
-Delays child speech development by ~2 years.

Front 57

Moderate Hearing Loss

Back 57

41-55 dB HL loss.
-Loud voice is only a whisper.

Front 58

Moderately Severe Hearing Loss

Back 58

56-70 dB HL loss.

Front 59

Severe Hearing Loss

Back 59

71-90 dB HL loss.
-3 year speech delay, probably will not develop speech spontaneously (without hearing aid).

Front 60

Profound Hearing Loss

Back 60

91+ dB HL loss
-Can't discriminate speech without aid.
-Can't understand speech with hearing aids alone.

Front 61

Place Theory of Hearing

Back 61

-regions of cochlea respond to specific frequencies.
-one octave every 3.5 mm
-the cochlea is a mechanical spectrum analyzer.

Front 62

Conductive Hearing Loss

Back 62

-the structures of the outer or middle ear do not work correctly.
-most easily treated.
-may respond to medical or surgical treatment.
-ear wax.
-fluid build up in the middle ear.
-damage of ossicles or ear drum (more serious).

Front 63

Sensorineural or Sensory Neural Hearing Loss

Back 63

-"nerve deafness"
-inner ear structures or nerves do not work correctly
-kills hair cells or damages nerves.
-likely to be permanent.
-Causes: hereditary, German measles (Rubella): prenatal, Meningitis, other diseases.Noise induced.

Front 64

Mixed Hearing Loss

Back 64

-both conductive and sensory neural.
-Temporary: prolonged exposure to 85+ dBA levels. Middle ear muscles adjust, but tire easily. Can't handle rapid bursts of sounds.
-Permanent: drug induced hearing loss (Streptomycin is a kind of antibiotic, when given high doses this can kill hair-cells in crista and macula). Loud sounds damages hair cells, which are not regenerated.

Front 65

Critical Band

Back 65

-A 1.2 mm band of cells along the organ of corti (35 mm) that responds to any single frequency.
-Involves about 1300 hair cells of the 30,000 hair cells total.

Front 66

Masking

Back 66

A noise that's generated to block or camoflague your ability to hear sound...the ability to distinguish a sound against background noise.

Front 67

Mels

Back 67

unit of pitch

Front 68

Otoacoustic Emissions

Back 68

Low level sounds produced by the cochlea.

Front 69

Synapse

Back 69

Connections between neurons are made primarily at junctions call synapses.

Front 70

Myelin

Back 70

-shields and protects
-coats the axon

Front 71

Tinnitus

Back 71

Ringing in the ears.

Front 72

Action Potential

Back 72

-The observed voltage.
-Sodium flowing in...potassium flowing out.
-Resting potential is -60 milivolts, action potential is 70 mV.
-Pump regulates as it moves on, follows action potential, goes back and forth.
-speed of 100 m/s when myelinated.
-diameter: 3-6 microns.

Front 73

Broca's area and Wernicke's area?

Back 73

Known to have strong involvement in speech production and language understanding.

Front 74

Broca's Aphasia

Back 74

-slow, impaired articulation, incomplete sentences.
-speech is nonfluent, labored, and halting.
-Intonation and stress patterns are deficient.
-misarticulations are common.
-speech is "telegraphic" (short phrases, only nouns and verbs)
-repetition is poor.
-comprehension is pretty good.

Front 75

Wernicke's Aphasia

Back 75

-sounds good, but meaningless sentences
-Speech is fluent but “empty” and garbled (word salad).
-Rate, intonation, and stress are normal.
-Substitutions of one word for another (“telephone”—“television”) are common.
-Comprehension and repetition are poor.

Front 76

Amplitude

Back 76

-Maximum displacement (up or down).
-A

Front 77

Period

Back 77

-Length of time for a complete cycle.
-T

Front 78

Frequency

Back 78

-Number of cycles per second.
-Hertz
-f=1/T

Front 79

Velocity of the wave

Back 79

the speed at which the vibrations propagate through the medium.

Front 80

wave

Back 80

-a disturbance which transfers energy.
-except in the case of light, it requires a medium.

Front 81

wavelength

Back 81

-the distance between crests (or the same phase point).
-lambda

Front 82

standing wave

Back 82

two identical waves moving in opposite directions.
-get alternating constructive and destructive interference at any given position along the medium.
-resulting wave "oscilliates in place".
-The sum is a transverse wave that doesn't appear to move.

Front 83

Fourier's Theorem

Back 83

Any periodic wave shape can be constructed from an appropriate fundamental and its related harmonics.

Front 84

Pressure

Back 84

-The amount of force acting over a unit area of surface, and the unit pressure used here is the dyne per square centimeter. Pressure corresponds to the amplitude of the wave.
-P=F/A
-Units: Pascal=N/m^2 or dynes/cm^2

Front 85

Power

Back 85

The amount of work done in a given time.
Units: Watts

Front 86

Force

Back 86

Units: Newton

Front 87

Energy

Back 87

Units: Joule

Front 88

Intensity

Back 88

-Intensity corresponds to the power of the wave; how many watts/cm^2 are moving through an area; intensity is proportional to the square of the pressure. Book says: The power transmitted along the wave—through an area of one square centimeter at right angles to the direction of propagation—is called the intensity of the sound wave.
-Units: W/cm^2

Front 89

Diffraction

Back 89

-Wave bends around an object and moves into the shadow behind it.
-Not due to a change in the medium or wave velocity.
-Depends on both the wavelength and size of the obstruction.

Front 90

Reflection

Back 90

-Waves bouncing off a surface.
-Angle of incidence and angle of reflection are equal.
-Parabolic reflectors can focus (concentrate) waves by reflecting them to a common point (the focus).

Front 91

Resonance

Back 91

-External force is applied in phase with natural frequency; energy is stored and builds up in the motion.
-This phenomenon, whereby a body undergoing forced vibration oscilliates with greatest amplitude for applied frequencies near its own natural frequency, is called resonance.

Front 92

Interference

Back 92

Two similar waves in the same place at the same time.

Front 93

Constructive Interference

Back 93

Pulses add together at the moment when they are in the same place at the same time; when the waves are in phase then teh two waves will add together and enhance.

Front 94

Destructive Interference

Back 94

one pulse is positive the other is negative, therefore at the moment when they are in the same place at the same time they cancel each other out; when the waves are out of phase they will disappear because they cancel each other out.

Front 95

Spatial Interference

Back 95

constructive or destructive interference depends on your position relative to the sources. If a half-wavelength difference in the paths (x), waves cancel. If a full-wavelength difference in the paths (x), waves add. Depends on the particular wavelength. (Interference in two dimensions: water ripples).

Front 96

Temporal Interference

Back 96

Interference in time…waves slowly go in and out of phase as you listen from the same position. Alternating constructive and destructive interference. We hear the average frequency: f(heard)=(f1+f2)/2. Amplitude varies with the difference (beat) in frequency.

Front 97

Beat Rate

Back 97

f(beat)=f2-f1

Front 98

Longitudinal

Back 98

Pressure wave; Oscillation is in the same direction (parallel to) as the propagation (Example: sound).

Front 99

Transverse

Back 99

Oscillation is perpendicular to the direction of propagation (example: ropes, light).

Front 100

Superposition

Back 100

More than one wave can be in the same place at the same time.

Front 101

Ultrasonic

Back 101

sound frequency greater than 20,000 Hz

Front 102

Infrasonic

Back 102

sound frequency less than 20 Hz

Front 103

Supersonic

Back 103

An object that moves faster than the speed of sound.

Front 104

Fundamental

Back 104

The 1st harmonic, lowest frequency that (the string) will naturally vibrate.

Front 105

Harmonic

Back 105

A harmonic is an integer multitude of f. Book says: The component whose frequency is twice the fundamental frequency is called the second harmonic, the component 3 times the fundamental frequency is called the third harmonic, and so forth…

Front 106

Overtone

Back 106

General term for anything higher than the fundamental.

Front 107

Timbre

Back 107

Another term for "tone quality".

Front 108

Loudness

Back 108

Proportional to the amplitude or intensity.

Front 109

Pitch

Back 109

Proportional to the frequency; very slightly affected by loudness...

Front 110

Tone Quality

Back 110

Unique sound of an instrument or voice. Affected by…the wave form (shape of the wave), amplitudes of harmonics, transients (attack and decay). Attack: how the note starts (very rapid changes, easily distorted when recording). Decay: how the note ends (higher energy oscillations are damped more quickly).

Front 111

White Noise

Back 111

-All frequencies present in equal amplitude, like white light has all colors in it.
-Has a larger component of high frequencies.
-Is a very annoying sound, and is used to call attention to faint sounds.

Front 112

Pink Noise

Back 112

-Same energy in each octave (energy depends on the square of the amplitude).
-Has a larger component of low frequencies.
-Is a calming, relaxing sound, and is used to mask unwanted sounds.

Front 113

Formant

Back 113

A specific frequency region wherein any harmonics are emphasized by the resonant qualities of the instrument (or vocal tract).

Front 114

SPL

Back 114

-Sound Pressure Level
-How loud is it?
-Units: decibel

Front 115

SIL

Back 115

-Sound Intensity Level
-How loud is it?
-Units: decibel

Front 116

dB

Back 116

decibel

Front 117

How does intensity vary with the distance from a source?

Back 117

Intensity decreases with the square of the distance.

Front 118

What determines the speed that a vibration (or a sound) travels?

Back 118

The density of the medium through which it travels.

Front 119

When are reflections inverted or not inverted?

Back 119

Rope) Fixed end inverts: wall pulls down to hold end in place, generating a negative (inverted) reflection. Free end reflects: No restraint, so end overshoots, generating a positive (not inverted) reflection.

Front 120

How do dB's change as identical sources are added or removed?

Back 120

• Calculate “how much louder” by doing SIL=10 log (New I/Old I). Double the intensity...+3dB, triple the intensity…+5dB, quadruple the intensity…+6dB.