Problem 6 - GPS W2 Two speakers (see Figure) are separated by a distance d=1m and emit sound wave of frequency f=1kHz. (in air, sound = 340 m/s). The speakers are considered as point sources. (a) Calculate the smallest angle theta for constructive interferences. (b) If D=30m, at what locations z should an observer stands to hear constructive interferences (i.e. maximum sound)? (c) At what locations z should observers stand to hear no sound. CE-d sine E Z

Your ear is capable of differentiating sounds that arrive at each ear just 0.34 ms apart, which is useful in determining where low frequency sound is originating from. (a) Suppose a low-frequency sound source is placed to the right of a person, whose ears are approximately 18 cm apart, and the speed of sound generated is 340 m/s. How long is the interval between when the sound arrives at the right ear and the sound arrives at the left ear? (b) Assume the same person was scuba diving and a low-frequency sound source was to the right of the scuba diver. How long is the interval between when the sound arrives at the right ear and the sound arrives at the left ear, if the speed of sound in water is 1500 m/s? (c) What is significant about the time interval of the two situations?

(a) What is the speed of sound in a medium where a 100kHz frequency produces a 5.96cm wavelength? (b) Which substance in Table 17.1 is this likely to be?

Loudspeakers can produce intense sounds with surprisingly small energy input in spite of their low efficiencies. Calculate the power input needed to produce a 90.0-dB sound intensity level for a 12.0-cm-diameter speaker that has an efficiency of 1.00% . (This value is the sound intensity level right at the speaker.)

Sound is more effectively transmitted into a stethoscope by direct contact rather than through the air, and it is further intensified by being concentrated on the smaller area of the eardrum. It is reasonable to assume that sound is transmitted into a stethoscope 100 times as effectively compared with transmission though the air. What, then, is the gain in decibels produced by a stethoscope that has a sound gathering area of 15.0 cm2, and concentrates the sound onto two eardrums with a total area of 0.900 cm2 with an efficiency of 40.0% ?

When poked by a spear, an operatic soprano lets out a 1200—Hz shriek. What is its wavelength if the speed of sound is 345 m/s?

SWI-1 Two speakers are in phase and are both playing a tone with a frequency of 250.0 Hz. A listener starts at the location of speaker 2 and moves along the x axis. At what values of x are the first 3 locations where he will hear an intensity minimum? Hint: these are the n = 0, 1, 2 points of destructive interference. Take the speed of sound in air to be 343 m/s. speaker 1 (0, 4.50m) speaker 2 (0, 0) X

IP-2 101 speakers with a spacing of one meter between adjacent speakers form a line 100m long on the ground (the x-z plane) onthe x axis. The total power output of all of the speakers is 2,500W. The shape of the wavefront arriving at point P is cylindrical as shown to the right. R=2m 50.0m 50.0m Find the intensity of the sound at point P assuming that all sound energy goes into the cylindrical wavefront shown (not including the two half circles at the ends). Answers IP-1 a) 6.22x10 W/m? IP-2 3.98W/m? b) 1.24x10 W/m? c) 4.97x10?W/m? d) 0.199W/m?

B3

Two waves Y1-6.3 sin (3297 t-0.0765 x + 8x) and Y2-8.3 sin (3297 t-0.0765 x + 9%) interfere. Compute: (a) the frequency (f) of cach wave, and (b) the wavelength (A.) of cach wave (All quantities are in SI units)