MULTIPLE CHOICE ANSWERS - SOUND

[mahcann]

B D A C C D C C B A A D
LOOKING GOOD

[jpcauchi]

1. B     330/512
2. D    Oscillates horizontally
3. A    10^7*10^-12=10^-5
4. C    4 times the radius, therefore 16th the intensity, 12 dB change, 58 dB
5. C    50 phon
6. D     330/(4*133)
7. C    3* previous answer
8. C    320/(2*L)
9. B    200-2000Hz is where the graph is flat - fidelity
10.B    The period shortens and the amplitude increases because the microphone is more sensitive to 3kHz than 1kHz
11. A   Baffleboad prevents out of phase waves from front and back interfering
12. D   The tweeter behind the tv cant diffract around the tv

[gamblor0]

Q 10 was A.
it said it has the same sound or something along those lines so the amplitude was the same

[SixWinged]

I seem to be getting the same as you guys

That Q10 was a tricky one considering it didn't seem like it continued on from Q9, had to be paying attention.

[kyzoo]

Got the exact same answers as OP

[coletrain]

so was q 10 a continuation of q9 or not? i dont remember

[kyzoo]

1. B     330/512
2. D    Oscillates horizontally
3. A    10^7*10^-12=10^-5
4. C    4 times the radius, therefore 16th the intensity, 12 dB change, 58 dB
5. C    50 phon
6. D     330/(4*133)
7. C    3* previous answer
8. C    320/(2*L)
9. B    200-2000Hz is where the graph is flat - fidelity
10.B    The period shortens and the amplitude increases because the microphone is more sensitive to 3kHz than 1kHz
11. A   Baffleboad prevents out of phase waves from front and back interfering
12. D   The tweeter behind the tv cant diffract around the tv

for 10, why does the amplitude increase? I'm 100% sure it said that the two soudns were of the same intensity level.

[SixWinged]

so was q 10 a continuation of q9 or not? i dont remember

Yeah, it was the same microphone. hence for the same sound intensity reaching the microphone, it would record a higher/lower value depending on frequency.

[m@tty]

10 is A, not B.

kyzoo is right. It said that the intensity was made to be EXACTLY the same after the frequency was changed.

[kyzoo]

so was q 10 a continuation of q9 or not? i dont remember

Yeah, it was the same microphone. hence for the same sound intensity reaching the microphone, it would record a higher/lower value depending on frequency.

but that's perceived loudness =/ I thought asme intensity produce same sound level regardless of how we hear it, and regardless of frequency

[SixWinged]

so was q 10 a continuation of q9 or not? i dont remember

Yeah, it was the same microphone. hence for the same sound intensity reaching the microphone, it would record a higher/lower value depending on frequency.

but that's perceived loudness =/ I thought asme intensity produce same sound level regardless of how we hear it, and regardless of frequency

Perceived loudness is the phon graphs with hearing. I can't remember the exact question, but it was asking for the value that the microphone obtains (for want of a better word). The microphone obtains a higher value for frequencies it is more sensitive to.

[kyzoo]

hmmm haha interesting dispute

[jpcauchi]

LOL true, interesting dispute

I wrote A first, then changed it when i realised that Q10 followed on from Q9

It said that the sound intensity was exactly the same when it reached the microphone
And the question said what would be read on the oscilloscope

And cos the y axis was in arbitrary units, the amplitude would be much higher. Cos at 1khz, the graph on the page prior had the output of the microphone at 0dB and at 3khz as +6dB.

So i figure the oscilloscope would have a higher output when its 3khz as opposed 1khz, even though the intensity was the same.

[garliczombie]

it was intensity level not phon though. so it should be A because it says the intensity level stays the same.

[John President]

The microphone is not of equal fidelity at 1000 and 3000 Hz though, so on the CRO display the 3000 Hz sound will have greater amplitude I believe...so B.