Exam 16: Sound and Hearing

One of the harmonics of a column of air open at one end and closed at the other has a frequency of 448 Hz and the next higher harmonic has a frequency of 576 Hz.What is the fundamental frequency of the air column?

A factory siren indicating the end of a shift has a frequency of 90.0 Hz.The speed of sound is . (a)What frequency is perceived by the occupant of a car traveling towards the factory at ? (b)What frequency is perceived by the occupant of a car traveling away from the factory at ?

You are driving along a highway at 35.0 m/s when you hear the siren of a police car approaching you from behind and you perceive the frequency as 1370 Hz.You are relieved that he is in pursuit of a different speeder when he continues past you,but now you perceive the frequency as 1330 Hz.What is the speed of the police car? The speed of sound in air is

A sound source emits 20.0 W of acoustical power spread equally in all directions.The threshold of hearing is .What is the sound intensity level 30.0 m from the source?

Which one of the following statements is true?

Two motors in a factory are running at slightly different rates.One runs at 825 rpm and the other at 786 rpm.You hear the sound intensity increase and then decrease periodically due to wave interference.How much time elapses between successive maxima of the sound intensity?

Two in-phase loudspeakers that emit sound with the same frequency are placed along a wall and are separated by a distance of 8.00 m.A person is standing 12.0 m away from the wall,equidistant from the loudspeakers.When the person moves 3.00 m parallel to the wall,she experiences destructive interference for the second time.What is the frequency of the sound? The speed of sound in the room is 343 m/s.CAREFUL! The distance to the wall is NOT much greater than the distance between the speakers.

An enclosed chamber with sound absorbing walls has a opening for an outside window.A loudspeaker is located outdoors,84 m away and facing the window.The intensity level of the sound entering the window space from the loudspeaker is 56 dB.Assume the acoustic output of the loudspeaker is uniform in all directions and that acoustic energy incident upon the ground is completely absorbed and therefore is not reflected into the window.The threshold of hearing is .The acoustic power output of the loudspeaker is closest to

When a rocket is traveling toward a mountain at 100 m/s,the sound waves from this rocket's engine approach the mountain at speed V.If the rocket doubles its speed to 200 m/s,the sound waves from the engine will now approach the mountain at speed

The tension in each of two strings is adjusted so that both vibrate at exactly 666 Hz.The tension in one of the strings is then increased slightly.As a result,six beats per second are heard when both strings vibrate.What is the new frequency of the string that was tightened?

A stationary siren emits sound of frequency 1000 Hz and wavelength 0.343 m.An observer who is moving toward the siren will measure a frequency f and wavelength λ for this sound such that

A bat emits a sound at a frequency of 30.0 kHz as it approaches a wall.The bat detects beats such that the frequency of the echo is 900 Hz higher than the frequency the bat is emitting.The speed of sound in air is 340 m/s.The speed of the bat is closest to

If the intensity level at distance d of one trombone is 70 dB,what is the intensity level of 76 identical trombones,all at distance d?

The speed of sound in an alcohol at a temperature of 20°C is 1260 m/s.The density of the alcohol at that temperature is At a temperature of 20°C,find the bulk modulus of the alcohol.

The howler monkey is the loudest land animal and,under some circumstances,can be heard up to a distance of 8.9 km.Assume the acoustic output of a howler to be uniform in all directions and that the threshold of hearing is .A juvenile howler monkey has an acoustic output of What is the ratio of the acoustic intensity produced by the juvenile howler to the reference intensity I₀,at a distance of 210 m?

A jet aircraft,in level flight at constant speed,is observed directly overhead.A sonic boom is heard later,at which time the line of sight to the aircraft forms a 56° angle with respect to the horizontal.The speed of sound is .What is the Mach number (the ratio of the speed of the jet to the speed of sound)for the aircraft?

Two stereo speakers mounted 4.52 m apart on a wall emit identical in-phase sound waves.You are standing at the opposite wall of the room at a point directly between the two speakers.You walk 2.11 m parallel to the wall,to a location where you first notice that the sound intensity drops to zero.If the wall along which you are walking is 10.7 m from the wall with the speakers,what is the wavelength of the sound waves? CAREFUL! The distance to the wall is NOT much greater than the distance between the speakers.

The lowest-pitch tone to resonate in a pipe of length L that is closed at one end and open at the other end is 200 Hz.Which one of the following frequencies will NOT resonate in the same pipe?

As you stand by the side of the road,a car approaches you at a constant speed,sounding its horn,and you hear a frequency of 80.0 Hz.After the car goes by,you hear a frequency of 60.0 Hz.What is the speed of the car? The speed of sound in the air is 343 m/s.

A supersonic plane passes overhead at a speed of 500 m/s.If you hear the sonic boom (shock wave)4.00 s after the plane is directly overhead,at what altitude is the plane flying? Assume the speed of sound in air is 340 m/s.