Ch. 5: Intensities

Question 1

Spatial refers to…

Answer 1

location, distance or space.

Question 2

Define ‘peak’.

Answer 2

maximum value

Question 3

Define ‘average’.

Answer 3

mathematical middle value

Question 4

Temporal refers to…

Answer 4

all time, transmit (pulse duration), and receive.

Question 5

Pulsed refers to…

Answer 5

transmit time only (ignoring listening time).

Question 6

What is spatial peak intensity?

Answer 6

The beam’s intensity at the location where it is at its maximum; I-sp

Question 7

What is spatial average intensity?

Answer 7

The average intensity across the beam’s entire cross-sectional area; I-sa

Question 8

Spatial peak intensity is always ___ than the spatial average intensity.

Answer 8

higher

Question 9

What is temporal peak intensity?

Answer 9

The intensity of the beam at the instant in time of its maximal value; I-tp

Question 10

What is maximum intensity?

Answer 10

The average intensity during the most intense half-cycle; I-max or I-m

Question 11

What is pulse average intensity?

Answer 11

The average intensity during the pulse duration (transmit only); I-pa

Question 12

What is the temporal average intensity?

Answer 12

The average intensity during the entire pulse repetition period (transmit + receive); I-ta

Question 13

Of the four temporal intensity measurements, which has the highest value?

Answer 13

temporal peak (I-tp) which is slightly higher than I-max.

Question 14

Which is the lowest of the temporal intensity measurements?

Answer 14

temporal average (I-ta)

Question 15

Temporal intensities from largest to smallest?

Answer 15

I-tp, I-max, I-pa, I-ta

Question 16

Which intensity is measured at the location where intensity is maximum and at the instant in time when the most powerful part of the pulse passes?

Answer 16

I-sptp

Question 17

Which intensity is measured at the location where intensity is maximum, averaged over the pulse duration?

Answer 17

I-sppa

Question 18

Which intensity is measured at the location where intensity is maximum and averaged over all time?

Answer 18

I-spta

Question 19

Which intensity is measured over the entire cross-sectional area of the sound beam and over all time?

Answer 19

I-sata

Question 20

Intensities may be reported in various ways with respect to…

Answer 20

time and space.

Question 21

The different measurements of intensities are important in…

Answer 21

the study of bioeffects.

Question 22

Which is the most relevant intensity with respect to tisue heating?

Answer 22

I-spta

Question 23

Intensities are reported in units of…

Answer 23

W/cm^2

Question 24

Peak measurements are ___ than average measurements.

Answer 24

larger

Question 25

Which intensity has the highest value?

Answer 25

I-sptp

Question 26

Which intensity has the lowest value?

Answer 26

I-sata

Question 27

What number describes the spread of a beam in space?

Answer 27

the beam uniformity coefficient (aka SP/SA factor)

Question 28

The beam uniformity coefficient (SP/SA factor) is reported in units of...

Answer 28

Trick question! It's unitless, with a value of 1 or greater.

Question 29

What describes the relationship of beam intensities with time?

Answer 29

The duty factor

Question 30

The duty factor is reported in units of...

Answer 30

Trick question! It's unitless, with a value between 0 and 1.

Question 31

In continuous wave u/s the pulse average and temporal average are the ___.

Answer 31

same. So SPTA = SPPA and SATA = SAPA.

Question 32

When pulsed and continuous wave sound beams have the same SPTP intensities, the continuous wave beam has the ___ SPTA intensity.

Answer 32

higher

Question 33

When pulse and continous wave sound beams have the same SATP intensities, the continuous wave beam has the ___ SATA intensity.

Answer 33

higher

Question 34

I-tp is the ___ intensity in time.

Answer 34

maximum

Question 35

I-m intensity is averaged over the most intense ___.

Answer 35

half-cycle

Question 36

I-pa is averaged during the ___.

Answer 36

pulse duration

Question 37

I-ta is averaged during the ___.

Answer 37

pulse repetition period

Question 38

I-sp is the ___ in space.

Answer 38

maximum

Question 39

I-sa is averaged over the ___.

Answer 39

cross-sectional area of the beam

Question 40

Rank the intensities from largest to smallest.

Answer 40

SPTP, I-m, SPPA, SPTA, SATA