Hearing Science Test 1

three parts of sound as a system

source, medium, receiver

source

(part of sound system) disturb the air molecules by its vibration, e.g., larynx, headphones, speaker

medium

(part of sound system) sound waves must travel through this, e.g., air, water

receiver

(part of sound system) detect the propagation of sound wave, e.g., ear

gas, liquid, solid

the mediums that sound travels in from fast to fastest

compression, rarefaction

molecules being closer together is called ____ while molecules being farther apart is called ____ (pressure and density higher vs. lower) in a sound wave

transverse

(type of wave) particles of medium move perpendicular to the direction of the wave

longitudinal

particles of medium move parallel to the direction of wave

longitudinal wave

What type of wave is a sound wave?

transverse wave

We plot sound as if it were what kind of wave? (pressure changes at one location over time)

complete cycle of sound wave

1. positive zero crossing

2. positive peak

3. negative zero crossing

4. negative peak

5. positive zero crossing

properties of sound

period, frequency, amplitude, phase

period/frequency

(sound property) how often pressure changes

amplitude

(sound property) how big pressure changes are; related to perceived loudness

phase

(sound property) when pressure changes began

period

the amount of time a sound wave takes to complete one cycle (seconds, milliseconds)

T=1/f

formula for period

wavelength

how long a cycle of a sound wave is in distance (meters, millimeters)

frequency

the number of cycles a sound wave finishes in the given amount of time (usually 1 sec.); measured in Hz

f=1/T

formula for frequency

peak, peak-to-peak, RMS

What are the three measures of amplitude?

peak amplitude x 0.707

formula for RMS

0, 90, 180, 270

the different degrees of starting phases of a sinusoidal wave

Why phase is important

-determines how waveforms add together

-plays a role in the perceived location of the sound

1, 2

To find the amplitude of a complex sine wave, you add amplitude __ + amplitude __

slowest

The period of a complex wave is the same as the ___ moving simple sine wave component

spectrum

the ___ is a way of looking at the components of a more complicated sound like speech or music

summing, decomposed

Principles of the Fourier Transfomation:

1. Any sound can be created by ___ enough pure tones w/diff. freq., amp., and phases

2. Any sound can be ____ into a series of pure tones w/diff. freq., amp., and phases

frequency, amplitude

While a sine wave shows time (x axis) vs. pressure (y axis), a frequency domain using spectrum shows _______ (x axis) vs. _____ (y axis)

spectrogram

shows spectra by Fourier analysis as they change over time

time, frequency

a spectrogram displays ____ on the x axis and ___ on the y axis

resonance

increased amplitude that occurs when the frequency of a sound (or a Fourier component of it) is equal or close to a natural frequency of the system

ear canal, basilar membrane

two parts of the auditory system that use resonance to help us process sound (outer ear, inner ear)

mass, elasticity

two properties of an object that influence its resonant frequency

length

Resonant frequency is determined by the ___ of the pipe (e.g., ear canal)

absolute threshold

lowest intensity at which a stimulus can be detected; intensity that can be detected 50% of the time

discrimination threshold

the minimal amount of change in a stimulus that can be detected

limits, adjustment, constant stimuli

classical methods for finding thresholds (method of ___)

method of limits

(classical method for finding threshold) determine the stimulus intensity at which the observer can either no longer detect the stimulus (high to low) or begins to detect it (low to high)

method of adjustment

(classical method for finding threshold) observer, NOT experimenter, adjusts stimulus intensity until observer can either no longer detect the stimulus or just begin to hear it)

method of constant stimuli

(classical method for finding threshold) determine the % of “yes” responses for a stimulus at a variety of different, randomly presented, stimulus intensities

psychometric function

percent “yes” detections as a function of stimulus level, meaning stimulus intensity is on x axis, percent of yes responses is on y axis; how method of constant stimuli is graphed; s-shaped

issues with method of limits

observer may lack engagement, presenter may be biased when presenting the stimuli

issues with method of adjustment

more complicated process, so observers may have more trouble adhering to the instructions

issues with method of constant stimuli

requires a complicated programming to randomize trials

sensory impression, decision process

Perception is controlled by what two basic internal processes?

noise

a random disturbance that can be confused w/signals; is always present inside humans or by environment

sensory impressions

any stimulus, even noise, produces a distribution of ____ _______

independent

Signal detection theory provides a way to characterize performance ______ (independent or dependent) of the listener’s criterion (i.e., strict vs. liberal) for answering yes or no

hit, miss, false alarm, correct rejection

Signal detection theory responses (yes vs. no) and signals (present vs. absent) result in what possible outcomes?