Acoustics

Question 1

Sound

Answer 1

Need a medium –> air molecules make elastic connections with each other and exert pressure

Rate of pressure waves stay constant throughout sound waves

Question 2

Speed of Wave

Answer 2

Frequency changes speed waves are released BUT not how fast the waves move

Question 3

Intensity

Answer 3

amount of sound power passing through a unit area

Question 4

Plane Wave

Answer 4

No matter how far from sound source, waves are the same –> Power & Pressure do not change

Question 5

Spherical Point Source

Answer 5

Sphere radiates equally in all directions, fewer rays go through last section than first (different than plane waves)

Question 6

Characteristic acoustic impediance

Answer 6

impediance is pressure/volume velocity

Question 7

impediance

Answer 7

Relationship between velocity and pressure

Question 8

eardrum impediance

Answer 8

fundamentally important, use 226 hz tone for tymps because there are no nodes or antinodes so same pressure anywhere in canal because of the long wavelength and no standing waves

Question 9

interaural level differences

Answer 9

Head shadow, best used for higher frequencies

diffraction occurs if dimensions are big enough, waves bend around the object

arithmetic sound level between 2 ears to determine where sound is in horizontal plane

Question 10

(binaural) interaural timing delay

Answer 10

2degrees=minimal audiblee angle, used more for lower frequencies, but can be used for high frequencies if modulated with low frequencies and have big time difference

~10 msec is time delay associated with the 2degrees angle –> big for ability to locale, .6msec is max delay sound can take if traveling all around the head

No time delay when directly facing source, greatest at 90degrees