Course:PHYS341/Archive/2016wTerm2/Assignments/A6

Practice Questions for Quiz 6, Friday Mar 10'

Textbook sections covered: 15.3, 15.5-7, Wood Lecture, 16.1-7, 16.10

1. If a complex tone consists of frequencies 200, 300, 400, 500 and 600 Hz, you perceive a pitch associated with what frequency?

(a) 100 Hz ✓
(b) 200 Hz
(c) 400 Hz
(d) 600 Hz
(e) 1 kHz
(f) 2 kHz

2.A violinist tunes her top two strings to 12-TET with fundamental frequencies 440 and 659.3 Hz. If the two strings are bowed together, what beat frequency will be heard? Reminder: the beat frequency is the difference between two close frequencies. (Warning: think what is going on here!)

(a) 1.4 Hz ✓
(b) 5.6 Hz
(c) 9.3 Hz
(d) 259.3 Hz
(e) 440 Hz
(f) 659.3 Hz

3. Wood is favoured for instrument sound boxes for the following reasons:

(a) It is much cheaper than, say, aluminum.
(b) It is easily and quickly available from cut trees.
(c) It has consistent properties: any two same-size pieces of, say, spruce, will be acoustically identical.
(d) Its orthotropic structure causes it to be more resonant at low frequencies than high frequencies. ✓
(e) With centuries of experience, we know how to deal with it. ✓
(f) Finished right, it has transcendent beauty. ✓

4. String instruments often have a hole (or holes) because:

(a) the sound echoes in the hole.
(b) the hole lets the sound out.(vague and not very helpful notion, but has some measure of truth about it).
(c) it adds an extra resonance to the sound box related to the Helmholtz "beer bottle" resonance.✓
(d) it lowers the lowest frequency of the sound box without having to thin the sound board too much.✓