Hearing Science Unit 4

Front 1

magnitude, root mean square, power

Back 1

Because peak to peak amplitude (sound pressure) is not always the most useful index for measuring ________, it's preferable to use the _________ formula to measure the overall ________ of the sound (or vibration).

Front 2

effective, area under the curve, mean, deviation

Back 2

RMS (aka:___________) magnitude is calculated by the following formula: RMS= √(Σx²/n) and is essentially used to calculate the _________________ or the square root of the _______ of the _________ scores squared.

Front 3

0, .707

Back 3

The mean for sinusoids and other symmetrical functions is ______. When the peak magnitude of a sinusoid is 1, the RMS = _______. If the peak magnitude of a sinusoid is any other number, that number is multiplied by this RMS value to calculate the new RMS.

Front 4

dB, calibrate

Back 4

The unit for RMS is μPa, which we then convert into ____ in order to survey sounds and ________ hearing and other test instruments.

Front 5

common logarithm

Back 5

The _________ ___________ (used to compute dB values) is the exponent to which the base 10 is raised to equal the transformed number.

Front 6

characteristic, mantissa

Back 6

dB is the logarithm of the ratio of 2 quantities: the _________ and the ____________.

Front 7

characteristic

Back 7

The ____________ of the log is equal to the exponent of 10 in scientific notation of the value to be converted (computed).

Front 8

mantissa

Back 8

The _________ of the log is a given number (constant) that can be looked up on a graph based on the coefficient of the scientific notation.

Front 9

acoustic intensity level (IL), w/m^2

Back 9

Acoustic intensity in dB is referred to as _________ _________ ____________ and has a reference level measurement in ________.

Front 10

sound pressure level, N/m^2

Back 10

Sound pressure in dB is referred to as _________ _________ __________ and has a reference level measurement in ________.

Front 11

20, 0

Back 11

____μPa (=___dB SPL) represents the lowest limit of human hearing (sound detection).

Front 12

0, 140

Back 12

dB are typically represented on a scale of __-___.

Front 13

attenuation

Back 13

The mile of standard cable is a measurement of _________ effect that refers to a signal becoming weaker the farther away it is from the source (ex: the longer a telephone cable is, the weaker the power output signal is at the end of the cable). This relationship is defined by the ratio of the power measured at the output at a cable n miles long compared to the power measured at the input: log10 (Wn/Wr)=-0.1n

Front 14

RMS

Back 14

The value registered on SLM (sound level meter) readout is based on __________ magnitude of the sound pressure.

Front 15

gain

Back 15

The _______ refers to an increase in the magnitude of a signal or sound as measured in dB SPL.

Front 16

loss (aka: attenuation)

Back 16

When a decrease is observed at the output of a certain system, it is called a ______.

Front 17

octave, octaves

Back 17

For any given frequency (Fo), one _________ above= 2*Fo and the following formula holds to solve for multiple _______ (n): Fn=2^n*Fo

Front 18

F

Back 18

T/F: Octave intervals of frequency represent equal frequency intervals (i.e. 3 octaves above 100 Hz=300 Hz)

Front 19

10; 2

Back 19

dB's are logarithmic to the base of ____ while octaves are logarithmic to the base of _____.

Front 20

decade, octave

Back 20

The base of 10 notational system for frequency is called the _________. The base of 2 notational system for frequency is called the _________.

Front 21

transient, aperiodic

Back 21

A __________ is a high amplitude, short-duration sound at the beginning of a waveform that occurs in phenomena such as musical sounds, noises or speech. These sounds are not continuous and thus ____________. It can sometimes contain a higher magnitude of high frequencies than the harmonic content of that sound. These types of sounds do not necessarily directly depend on the frequency of the tone they initiate.

Front 22

complex, pure tones

Back 22

A sawtooth wave is a __________ tone that can be synthesized (produced) via a combination of discrete __________ _________.

Front 23

Fourier analysis

Back 23

The process of breaking down any tone into its pure tone constituents is referred to as ________ __________.

Front 24

noise

Back 24

_________ is defined as a random, aperiodic signal or sound.

Front 25

all audible frequencies

Back 25

white noise contains __________________. It has a hissing quality that can be roughly simulated by making a sustained /s/ sound.

Front 26

Gaussian

Back 26

The __________ distribution is characteristic of noise produced by thermal effects in electronic circuits, also perceived as a hissing sound (like white noise).

Front 27

acoustic intensities

Back 27

The resultant of the summation of uncorrelated (independently generated) sounds is the sum of the ____________ ____________ of the sounds.

Front 28

frequencies

Back 28

spectrum level (aka: level per cycle) is used to determine the intensity level for all __________ in a spectrum.

Front 29

bandwidth

Back 29

___________ refers to the range of frequencies spanned by a noise.

Front 30

1

Back 30

Bandwidth is divided by a reference bandwidth (unit bandwidth) = _____ Hz.

Front 31

constant

Back 31

The long-time average intensity of a noise is ________ across its bandwidth.

Front 32

time, amplitude

Back 32

In the temporal view of sounds, _____ is on the x-axis and _______ is on the y-axis.

Front 33

time history

Back 33

When a sound is characterized as having a certain waveform, such as sinusoidal, what is being described is the ______ __________ of the sound. This is what's displayed on the oscilloscope.

Front 34

spectrum, frequency, magnitude

Back 34

A _________ graph shows the "recipe" or sound signal's makeup. _______ is on the x-axis and ________ is on the y-axis.

Front 35

line (discrete), continuous

Back 35

Tones have ________ spectra while noises have _________ spectra.

Front 36

continuous, power spectrum, power, constant

Back 36

Gaussian noise is the simplest example of a _____________ spectrum. This is also referred to as a _______ _________ b/c it depicts the average amplitude contribution of each frequency to the total _________ in the signal, and this average contribution is what is depicted as __________.

Front 37

instantaneous, amplitude

Back 37

Spectral analysis of a brief snapshot of a noise is known as _________ and is depicted in an ___________ spectrum.

Front 38

phase

Back 38

The ________ spectrum must also be determined to fully specify a signal/sound with relation to the combination of simple or complex tones.

Front 39

frequency response

Back 39

Filters provide a simple and efficient way to characterize a system's _________ ___________.

Front 40

low-pass, high-pass, band-pass

Back 40

A _______________ filter rejects high frequencies while a __________ filter rejects low frequencies. A ___________ filter only allows frequencies within a certain range to pass through.

Front 41

narrow-band (band-limited)

Back 41

When wide-band noise is filtered, it results in _______ noise.

Front 42

stop-band (band-reject)

Back 42

When a combination of high and low-pass filters are used to reject frequencies within a certain band, this results in ___________ filtering.

Front 43

notch

Back 43

A stop-band filter intended to reject a specific frequency is known as a _________ filter.

Front 44

3, 50, 70.7

Back 44

The cut-off frequency can be determined by finding the point on the slope of the filter that is ___dB down (decreased relative output) from the pass frequency. This value is significant b/c it represents a half-power point, the point along the frequency axis at which the signal magnitude drops by _____% power (=______% sound pressure).

Front 45

nominal (half-power)

Back 45

The span of frequencies between the half-power points is referred to as the ______________ bandwidth.

Front 46

bandwidths, center frequency

Back 46

Filters are characterized by their ___________ and _____________.

Front 47

octaves (or quarter octaves)

Back 47

Bandwidths are stated in ________.

Front 48

attenuation

Back 48

Not all energy in the spectrum of filtered sound is confined to the frequency range indicated by the corner frequencies. The further above or below a corner frequency, the greater amount of _____________.

Front 49

roll-off (rejection rate), dB/octave

Back 49

How much sound leaks through and how much is attenuated depends on the ____________ of the filter. This parameter of filters is measured in ______.

Front 50

corner, roll-offs

Back 50

To completely specify the response characteristics of a particular filter, both the ________ frequency(ies) and the __________ of the filter must be stated.

Front 51

electronic

Back 51

Which type of filter is preferred due to the fact that they are easier to build, easier to design for specific response characteristics, easier to adjust, and less expensive to implement? acoustic or electronic?

Front 52

narrow

Back 52

Adjustable ____________ band-pass filters can be used to measure the contribution of each component of a complex sound, a form of spectral analysis.

Front 53

time-dependent amplitude, frequency, phase variations (modulations)

Back 53

Temporal characteristics of a sound on its spectrum include: ________-_______ ___________, ______________, and/or ____________ ____________.

Front 54

gating, impulses

Back 54

The transformation that describes how a signal is turned on and off is referred to as the ___________ function (time window), and is found by 1st examining the spectra of simple _____________.

Front 55

dc (discharge) pulse

Back 55

Rapidly switching a direct current on and off creates a ___________.

Front 56

nulls

Back 56

Spectral ________ occur at frequencies equal to the reciprocal of the pulse-duration (1/D).

Front 57

higher, wider

Back 57

The shorter the duration of the pulse, the _______ is the frequency of the first null or _________ the intervals between the nulls.

Front 58

lobe

Back 58

The hill between nulls is referred to as a _______.

Front 59

less

Back 59

The magnitude of the main lobe is proportional to the pulse duration, so that when there is less on-time ________ energy is present.

Front 60

acoustic click, band-pass

Back 60

If a dc pulse (which does not occur naturally) is used to drive an earphone or loudspeaker, the transduced sound is called a(n) _______ ___________, which generates a fairly broad spectrum. This occurs because transducers, such as earphones, act like ________________ filters in that they fail to operate efficiently at very low and very high frequencies.

Front 61

duration, bandwidth

Back 61

Heisenberg's uncertainty principle states that as ___________ decreases, ____________ must increase.

Front 62

increasing, gradually

Back 62

The splattering caused by gating the sinusoid can be reduced effectively by simply ___________ the duration of the tone burst and turning the tone on/off more __________.

Front 63

plateau duration

Back 63

________ _____________ is the steady-state part of the tone burst.

Front 64

overall energy

Back 64

Effective duration represents the ________ _________ of the sound.

Front 65

0, 90

Back 65

High frequency splatter is minimized by gating at the ____ degree phase while low frequency splatter is minimized by gating at the ____ degree phase.

Front 66

spectrum, waveform

Back 66

Changes in the time domain influence the __________. Changes in the frequency domain influence the ___________.

Front 67

F

Back 67

T/F: The frequency and time domains are independent.

Front 68

phase

Back 68

__________ distortion occurs when the output signal shifts (so that it's starting at a different degree) relative to the input signal.

Front 69

nonlinearity

Back 69

Amplitude distortion is the form of distortion most commonly associated with _______________ b/c the graph of the magnitude output signal vs the input signal is not a straight line.

Front 70

peak clipping, square

Back 70

________ ____________ occurs when the output is limited to particular positive and/or negative values. This may result in a _________ wave.

Front 71

driving, not present

Back 71

The result of nonlinearity is that energy is no longer focused exclusively at the __________ frequencies. The presence of amplitude distortion is characterized by the production of frequency components in the spectrum of the output signal that are ____________ at the input.

Front 72

total harmonic distortion

Back 72

_________ ____________ ____________ is measured as a % computed from the ratio of the total energy in the distortion components/total energy of the sound.

Front 73

sound pressure

Back 73

The dB is defined in terms of acoustic intensity but also can be calculated conveniently from _________ _________, a more practical measure of sound magnitude.

Front 74

noise, tone, aperiodic, periodic, complex, simple, random, transient

Back 74

Sounds may be categorized via different schemes:

Front 75

intensity (power rule)

Back 75

Uncorrelated (random sounds) add according to acoustic ___________.

Front 76

amplitude, phase

Back 76

Spectral analysis gives __________ and ___________ vs frequency.

Front 77

discrete

Back 77

For pure and complex tones, the spectra are ________ and their graphs are portrayed by lines for each frequency component.

Front 78

continuous (energy is spread continuously over frequency, even if unevenly).

Back 78

Transient and random noises have _______ spectra.

Front 79

frequency, filters

Back 79

Sound can be shaped in the __________ domain. A common means of doing so is with _______.

Front 80

time, spectrum

Back 80

Gating/windowing is shaping in the ________ domain, but it has effects on the _________, due to reciprocity between time and frequency.

Front 81

continuous, transient, impulses, clicks

Back 81

Turning signals on and off for just a "burst" of sound, even when a pure tone is being switched, causes the spectrum to become ___________ because it has been rendered a __________. This phenomenon can be understood from the spectra of __________, which are continuous and predictable from their duration, but also of interest in themselves, producing sounds called _________.

Front 82

distortion, filtering, phase

Back 82

Other than gain or attenuation, any change in a signal/sound as it moves through a system is called _________. Some such changes (like __________ and ________ effects) are still results of linear processes and do not create new energy or redistribute it.

Front 83

amplitude distortion

Back 83

When amplitude fails to change proportionally or two sounds add disproportionally, ____________ ____________ results, wherein power is redistributed, creating new frequency components not present in the input signal.

Front 84

narrow band filter, broad

Back 84

The SHO (simple harmonic oscillator) is tuned to a specific frequency (determined by the ratio of mass & stiffness). Therefore, it's frequency response can be thought of as a _________ _________ _________. Impulses can "drive" the SHO, namely such pulses have __________ spectra.

Front 85

amplitude spectrum

Back 85

When we look at the time analysis (time history) of sinusoidal pulses (aka: tone bursts) or clicks vs. white noise (for example), we are struck by differences. On the other hand, they all share a common general type of spectrum, called a(n) _____________ _______________.

Front 86

transient

Back 86

A ___________ is the type of sound you get when you turn a sinusoid on & off (gating it) for just a few cycles.

Front 87

dB

Back 87

Sound pressure level is measured in ____.

Front 88

pure tone

Back 88

The amplitude or power spectrum of a sound that has only 1 line at 1000 Hz must be a ________ ________.

Front 89

continuous

Back 89

Unlike tones spectra of noises are ________________.

Front 90

3dB down, half

Back 90

We call cut-off frequency of filters half power points because at these frequencies the output will be _______ & _____ of the maximum power passed by the filter.

Front 91

plateau duration, rise/fall time, shape

Back 91

_____________, _____________, & ___________ contribute to the spectrum's appearance as a result of gating function (ramping the sinusoid)

Front 92

6

Back 92

When a measured value of SP is doubled in intensity, the increase is always _____dB.

Front 93

dimensionless

Back 93

dB is a ____________ unit of measure.

Front 94

random aperiodic

Back 94

A noise is filtered so as to limit its energy to a very narrow frequency range centered at 2000Hz. The sound produced is perceived to have a fairly definite pitch, but it's still a noise by our definition because it's still a __________ ___________ sound, in reality.

Front 95

continuous

Back 95

Discharge impulses (transients) and clicks (similar to snapping fingers) have a _________ line spectra.

Front 96

centered around the sinusoid's frequency, splattered, continuous

Back 96

Distinguishing characteristics of sinusoidal pulses or "tone bursts" is that their power is ___________________, but _________ forming a __________ spectrum.

Front 97

broad continuous, nulls, duration

Back 97

An impulsive signal, like a dc pulse whose duration(d)=100 μPa will have a ________ _________ spectrum, but with _______ related to it's ________ at intervals of 1/d=10,000 Hz.