Ch 4 (MIDTERM) Flashcards
Basic Trig
SohCahToa
Starting phase
What phrase the object starts to vibrate
0,90,180,270,360
Instantaneous phase
Point in displacement cycle at time of measurement
Amplitude
Displacement of particles
Instantaneous amplitude
Amplitude at a specific moment in time
Peak amplitude
Max amplitude
Peak-to-peak amplitude
Compression to rarefaction, peak to trough
Complex tones
Multiple frequencies
Most common in speech
Pure tones
Only made up of one frequency
Periodic
Takes same amount of time for each cycle
When there is only one frequency, or the frequency make-up are harmonics of the fundamental frequency
Aperiodic
Takes different amounts of time for each cycle
When there is no pattern to the frequencies in the sound, usually made up of ALL frequencies within a certain range
Waveform
X=time, Y=amplitude
Looks like a wave
Spectrum
Shows frequency content
Frequency makeup of complex sounds
x-axis is frequency, y-axis is amplitude or phase
Line spectrum
A single line, usually harmonics (periodic) tone
Continuous spectrum
Contains all frequencies within a range, usually complex aperiodic noise
Amplitude spectrum
X axis = frequency
Y axis = Amplitude
Shows amplitude of each frequency in sound
Phase Spectrum
X axis = frequency
Y axis = phase
Shows the phase at which each frequency starts
Spectogram
3D representation of time domain, frequency Y-axis and shading shows intensity
Sine waves/Simple harmonic motion
Periodic in nature
single frequency
looks like a sine wave
one line in amp spectrum
on dot in phase spectrum
Summing pure tones of the same Hz
Add sine waves by summing the amplitude of vibration at each point in time
If 2 of the sine waves of same frequency at same phase: vibration/amplitude amplified, constructive interference
If 2 of the sine waves of same frequency at different/opposite phase: vibration/amplitude deleted, Destructive interference
Summing different pure tones
Creates COMPLEX sound
Beats
When 2 pure tones of equal intensity and slightly different frequency combine, causes sensation of listening to a single tone pulsating
Harmonics
Created when summing 2 or more specific pure tones that are whole number multiples of the fundamental frequency
Harmonics: whole number multiples of the lowest tone (fundamental frequency which is not always the lowest number in a sequence)
usually, when harmonics of a fundamental frequency are in a sound, it creates a complex PERIODIC sound since it has structure to the frequency make up
Octave scale
Doubling frequency is equal to 1 octave
Distortion
Change in a sound due to inaccurate production/transmission/reproduction
Fourier’s Theorem
Any wave can be broken down into component parts
Spectral analysis to analyze different frequency components
Complex periodic waveforms
Either looks like a square, triangle, or saw-tooth (symmetrical)
Has multiple lines in amplitude spectrum (of harmonics)
has multiple dots in phase spectrum (of the same phase)
Three types of complex periodic waveforms:
Square wave
Triangular wave
Saw-tooth wave
Square wave
-6dB/octave
Harmonics are ODD
Triangular wave
-12dB/octave
Harmonics are ODD
Saw-tooth wave
-6dB/octave
Harmonics are EVEN or ODD
Complex Aperiodic
Waveform is chaotic
One continuous line in amplitude spectrum
Multiple random dots in phase spectrum
Noise
Sound made up of ALL types of frequencies in a range
APERIODIC (no consistency in frequency makeup) and Complex (more than 1 frequency)
White noise (guaissian)
Continuous spectrum
contains ALL possible frequencies of same average intensity
Broad band noise
Contains ALL frequencies within a broad range
Narrow band noise
Contains all frequencies within a narrow limit
Usually a specific frequency
used to cover up frequency that crosses over from insert phone during audiogram
Pink noise
Less higher energy frequency, has a -3dB/octave slope
Click
Transient signal
Very short duration like the clicking of a pen
used in ABR
ABR (Auditory Brainstem Response)
Using surface electrodes to measure brain response to sounds
Often not diagnostic, for screening purposes
Specificity
Ruling out those who do not need further attention. If specificity is low, there are many false positives
Sensitivity
Identifying who does need help
If sensitivity is low, there are many false negatives
