Science and Technology of Musical Sound

Phys 1251.001 Practice Exam Unit 2

1. In the human ear, frequency is "decoded" by:

A. the range of motion of the ear drum. B. the intensity of the sound. C. resonant vibrations at different points along the Basilar membrane. D. by the semicircular canal. E. by resonances in the ossicles.

2. The ear is protected from damage due to sudden loud sounds by what mechanism? A. the ear drum cannot respond to percussion. B. the muscles of the middle ear contract reflexively on percussion. C. the cochlea does not transmit percussion in the perilymph. D. the hair cells will not respond to a sudden motion of the perilymph. E. the ear is unprotected.

3. An ensemble of eight (8) people each playing at the sample loudness will sound

how much louder than one (1) of them performing as a soloist? A. equal loudness. B. twice as loud (2x). C. ten times as loud (10x). D. one hundred times as loud (100x). E. not enough information.

4. What is the Sound Intensity Level (SIL) of a sound that has an intensity of 2.0 x 10-4 W/m2? A. -37 dB B. 42 dB C. 60 dB D. 83 dB E. 124 dB

5. Out of doors an orator is speaking. If the intensity is 1.0 x 10-4 W/m2 at one

meter (1m) in front of the podium, what is the intensity on the last row, 32 meters away? A. 1.0 x 10-4 W/m2 B. 1.8 x 10-5 W/m2 C. 3.1 x 10-6 W/m2 D. 1.0 x 10-8 W/m2 E. 9.8 x 10-8 W/m2

6. The range of normal human hearing is:

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A. 2000 - 5000 Hz B. 20 - 2000 Hz C. 200 - 20,000 Hz D. 20 - 20,000 Hz E. 20 kHz – 20,000 kHz

7. The wavelength of a 2,000 Hz string wave on a string of mass density .001 kg/m

and a tension of 1000 N at 20C is: A. 0.5m B. 0.172 m C. 1000 m D. 2.000 m E. 343. m

8. What is the fundamental frequency of a wave on a string that is 0.25 m meters

long with a mass density of 0.01 kg/m and is stretched with a tension of 156 N? A. 31200 Hz B. 62400 Hz C. 250 Hz D. 500 Hz E. 1372 Hz

9. The property of waves that accounts for the ability to hear around corners is:

A. Reflection B. Refraction C. Diffraction D. Interference E. Doppler Effect

10. The property of waves that accounts for the absence of thunder after some

lighting flashes due to variations in the temperature of the air is: A. Reflection B. Refraction C. Diffraction D. Interference E. Doppler Effect

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11. The property of waves that causes a column loud speaker to produce a "focused" beam of sound is: A. Reflection B. Refraction C. Diffraction D. Interference E. Doppler Effect

12. The property of waves that causes a train horn to change pitch as it passes is:

A. Reflection B. Refraction C. Diffraction D. Interference E. Doppler Effect

13. The primary cause of reverberation is:

A. Reflection B. Refraction C. Diffraction D. Interference E. Doppler Effect

14. The property of waves that permit submarines to determine the range to

underwater objects using their “pings” is: A. Reflection B. Refraction C. Diffraction D. Interference E. Doppler Effect

15. Two tones of equal intensity are played at the same time; one has a frequency of

505 Hz the other 503 Hz. What will you hear? A. Both tones independently. B. A tone of 504 Hz that beats with a frequency of 2 Hz. C. A single tone of 1008 Hz. D. A tone of 504 Hz that gets louder and softer 503 times a second. E. A tone that is 252 Hz and rough sounding.

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16. A room is 20 m wide and 30 m long and 10 m high with a volume of 6000 m3 and a surface area of 2200 m2. If all the surfaces are tile on concrete with an absorption coefficient of a = 0.1, what is the reverberation time? A. 27 sec B. 8.8 sec C. 4.4 sec D. 0.44 sec E. 0.27 sec

17. In an equal tempered scale, two notes that differ by a semitone: A. have a difference in frequency of 0.5 Hz B. have a ratio of frequencies of 2 C. differ in pitch by 100¢ D. differ in pitch by 1200¢ E. have a ratio of frequencies of 1.5.

18. Two pitches that differ by an octave:

A. have a difference in frequency of 440 Hz B. have a ratio of frequencies that is approximately 5/4 =1.25 C. have a ratio of frequencies that is approximately 4/3=1.33 D. have a ratio of frequencies that is approximately 3/2=1.50 E. have a ratio of frequencies that is approximately 2.00

19. If a piano is tuned to the just tempered scale so that A4 is 440.0 Hz, what is the

frequency of the perfect fifth (E5) be? A. 220 Hz B. 330 Hz C. 550 Hz D. 660 Hz E. 880 Hz

20. Reverberation in a room is a good thing for which of the following reasons?

A. It makes speech easier to understand. B. It is tunes the pitch of the sound. C. It makes the sound intensity more uniform throughout the room. D. It softens the sound. E. It is not really a good thing.

21. The Just Noticeable Difference (JND) in Sound Intensity Level (SIL) is

A. a cent. B. a Bel. C. a deciBel. D. a sone. E. a phon.

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22. A plucked string has a different timbre from a bowed string because (choose the best answer): A. The overtones have different frequencies. B. The bow adds its own vibrations to the vibration recipe. C. The plucked string sound has more transients and the harmonic have different intensities. D. The bow significantly changes the tension in the string. E. The bow usually produces longitudinal vibrations that the plucked string doesn't have.

23. Tightening the tuning peg on a stringed instrument:

A. raises the pitch because the length is shortened. B. raises the pitch because the stiffness of the wire is increased. C. raises the pitch because the tension is increased. D. raised the pitch because the mass of the wire is reduced. E. lowers the pitch because the velocity of the wave on the string is reduced.

24. One important advantage of a piano over a harpsichord is:

A. a piano is more portable. B. the improved timbre of the piano. C. the ability of the piano to play loud or soft. D. the shape of the cabinet. E. the piano is tuned to an equal tempered scale.

25. A violin is tuned so that the fundamental of the G string is 380 Hz. What is the frequency of the fourth harmonic? A. 384 Hz B. 440 Hz C. 760 Hz D. 1520 Hz E. 6080 Hz

Answer Key: 1. 2. 3. 4. 5 6. 7. 8. 9. 10. C B B D E D A C C B 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. D E A A B C C E D C 21. 22. 23. 24. 25. C C C C D