OUTLINE FOR SESSION 1


1) BASIC TASK: TO IDENTIFY THE SOUND SOURCE

2) BASIC PROBLEM: ONE RECEPTOR SURFACE

3) SCHEME:

A) TRANSDUCTION TO A NEURAL CODE
B) PROCESS AND INTEGRATE
     PERCEIVE AND RESPOND
4) BASIC ATTRIBUTES OF SIGNAL:
FREQUENCY
INTENSITY
TIME
COMPLEX COMBINATIONS

OUTLINE FOR SESSION 2: SINUSOIDS


THE BASIC SOUND

BASIC CONCEPTS:

VIBRATION: A FUNCTION OF MASS, ELASTICITY, AND A MOMENTARY FORCE
FOURIER ANALYSIS

3) THE SINUSOID:

THE TRIGONOMETRY sin a = A/B
THE UNIT CIRCLE
SIMPLE HARMONIC MOTION: AMPLITUDE WITH TIME
PROPERTIES OF A SINUSOID
FREQ. (PERIOD); AMPLITUDE; PHASE; WAVE LENGTH
MEASURES OF AMPLITUDE:
INSTANTANEOUS; PEAK; ROOT-MEAN-SQUARE
6) A CLASSIC OSCILLATOR A WEIGHT AND A SPRING
 

OUTLINE FOR SESSION 3: SOUND TRANSMISSION


PRELUDE: NEWTONS LAW'S OF MOTION

INERTIA AND MOMENTUM
A = F/M or F = M * A
FORCES ARE EQUAL BUT OPPOSITE

VIBRATING OBJECTS EXERT FORCE

FORCE UNITS ARE M * DISTANCE / T * T
[UNITS ARE NEWTONS OR DYNES]
AND DO WORK: W = F * DISTANCE
[UNITS ARE JOULES AND ERGS]
WITH POWER: P = W/TIME
[UNITS ARE WATTS]

NOTE: P = W/T; W = F * D; P = F * (D/T) OR

P = F * VELOCITY

BACK TO THE SPRING AND THE WEIGHT

SUPPOSE MASS IS HIGH: A IS LOW
SUPPOSE MASS IS LOW: A IS HIGH
WHAT ABOUT STIFFNESS OF SPRING?
F = -S * L : SO IF S IS HIGH, L IS LOW
IF S IS LOW, L IS HIGH: FILTER EFFECTS
RELEVANCE TO SOUND

AIR IS ELASTIC, RESISTS DEFORMATION, AND HAS MASS

IMAGINE A VIBRATING OBJECT IN AIR

WAVES OF DENSITY CHANGES: CONDENSATION/RAREFACTION
INCREASES AND DECREASES IN PRESSURE
WAVE HAS FREQUENCY, PHASE AND AMPLITUDE
MEASURES OF AMPLITUDE: PRESSURE OR POWER:
PRESSURE = FORCE/AREA and
POWER = PRESSURE SQUARED

OTHER WAVE CONCEPTS

dB: THE DECIBEL
REDUCES RANGE
FITS SENSATIONS
dB SPL, dB SL, and dB HL

EFFECT OF DISTANCE ON INTENSITY
IMPLICATION FOR HEARING

THE CONCEPT OF IMPEDANCE

THE EFFECTS OF RESISTANCE AND REACTANCE: (MASS ñ STIFFNESS)
THE IMPEDANCE OF OBJECTS:
ZC = DENSITY * SPEED OF SOUND AND
I = PRESSURE-SQUARED / IMPEDANCE
EFFECTS ON AIR TO WATER SHIFT

IMPLICATION FOR HEARING
THE CONCEPT OF STANDING WAVES, IN STRINGS AND IN PIPES:
IMPLICATION FOR HEARING

SOUND SHADOWS: BLOCKING OF SOUND AND THE WAVELENGTH OF SOUND:
IMPLICATION FOR HEARING
 

OUTLINE OF SESSION 4: COMPLEX STIMULI


1: FOURIER ANALYSIS

A) FIGURE 4.1 (and others) DEPICTING WAVES IN THE TIME AND FREQUENCY DOMAIN
B) THE FUNDAMENTAL FREQUENCY AND HARMONICS
C) FOURIER ANALYSIS OF CLICKS AND BRIEF STIMULI (FIGURE 4.2)
2: NOISE
AMPLITUDE VARIATION THAT IS RANDOM IN TIME (FIGURE 4.3): GAUSSIAN, WHITE, AND PINK NOISE.
TOTAL POWER AND POWER PER UNIT BAND WIDTH (SPECTRUM LEVEL, No)
Total power given No:
TP = No + 10 log BW.
IN GENERAL: ADD POWER NOT dB
No IS IMPORTANT WHEN PREDICTING MASKING
FOURIER SPECTRA FOR CLICKS AND PERIODIC TRANSIENTS

3: BEATS AND AMPLITUDE MODULATION
A) LARGE F DIFFERENCES: ADDITION

SMALL F DIFFERENCES: BEATS
B) AMPLITUDE MODULATION:
THE AMPLITUDE OF A SIN WAVE VARIES SINUSOIDALLY
C) FREQUENCY MODULATION: FREQUENCY OF A SIN WAVE VARIES SINUSOIDALLY

4: AN EXAMPLE OF AN EXPERIMENT USING COMPLEX STIMULI: AMPLITUDE MODULATED FREQUENCY MODULATION AND EVOKED POTENTIALS

Stefanatos, Green, & Ratcliff (1989)