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Sound & Hearing

Hearing is the ability to perceive sounds by detecting vibrations or changes in pressure through the ear. Sounds may be heard through solid, liquid or gaseous matter. Hearing is one of the traditional five senses. If someone has the inability to hear it is called deafness. Sound is the mechanical oscillating wave of pressure transmitted through some medium. It is composed of frequencies within the range of hearing.  

In vertebrates, hearing is performed by the auditory system. Vibrations of sound are detected by the ear and transduced into nerve impulses. These nerve impulses are then perceived by the brain. Similar to the sensation of touch, hearing requires sensitivity to the movement of molecules in the world outside the organism. Hearing and touch sensations are types of mechanosensation.

The human ear has three main components, the outer ear, the middle ear and the inner ear. The outer ear includes the visible part of the ear, the auditory canal and the eardrum. The middle ear consists of a small air filled chamber that is located behind the eardrum. Within this chamber are three small bones referred to collectively as the ossicles. The inner ear contains the cochlea. The cochlea is a spiral shaped fluid filled tube that is the organ of auditory transduction.


Categories within Sound & Hearing

Type of Interference and intensity level problems

1. There are two speakers at the front of the room. Each is outputting a 250Hz pure tone. For each of the following situations, will you hear constructive interference (a loud noise) or destructive interference (soft or no noise). Lambda represents the wavelength of the 250Hz tone. Choices: Constructive, Destructive. a. You are

Physics: Tuning fork, harmonics, transverse waves on a string

1. A tuning fork is sounded above a (narrow) resonating tube as in lab. The first resonant situation occurs when the water level is 0.08 m from the top of the tube, and the second when the level is at 0.24 m from the top. Let vsound = 340 m/s. a) Where is the water level for the third resonant point? b) What is the frequ

Tube filled with different media

The fundamental frequency of an open-open tube is 1500 Hz when the tube is filled with 0 degree Celsius helium. What is its frequency when filled with 0 degree Celsius air?

Speed of Sound and Doppler Effect

The speed of sound in air is about 660miles/hour. A passenger train approaches an unguarded railroad crossing at a constant speed of 60 miles/hour and the locomotive sounds its horn which has a frequency of 400 Hz. [A]. What frequency does a listener standing near the crossing hear? [B]. If the train continues past the

Sound travelling time through multiple mediums

An explosion occurs at the end of a pier. The sound reaches the other end of the pier by traveling through three media: air, fresh water and a slender metal handrail. The speeds of sound in air, water, and the handrail are 343, 1482, and 5040 m/s. The sound travels a distance of 125 m in each medium. a.) Which medium doe

Wave Length

Calculate the wavelength of the sound from a tuning fork. See attached file for full problem description.

Superposition of sound waves

Two speakers are driven by the same oscillator whose frequency is f. They are located a distance d from each other on a vertical pole. A man walks straight toward the lower speaker in a direction perpendicular to the pole, as shown in Figure P14.10. (Note the answers must be in all variables) (a) How many times will he hea

Harmonics of a Piano

(See attached file for full problem description with proper symbols and diagram) --- Harmonics of a Piano Wire A piano tuner stretches a steel piano wire with a tension of 800 N. The steel wire has a length of 0.400 m and a mass of 3.00 g. Part A: What is the frequency f1 of the string's fundamental mode of vibration?

Standing Waves

(See attached file for full problem description and figures) --- 21.8 The figure shows a standing wave oscillating at 100 Hz on a string. Part A : What is the wave speed? 21.5 A 40-cm-long tube has a 40-cm-long insert that can be pulled in and out. A vibrating tuning fork is held next to the tube. As the ins

Calculating frequency based on velocity and sound frequency

Taking right to be positive, if a speaker is moving at a velocity of -22 m/s while emitting a sound of frequency 1385 Hz, what frequency will you hear? If the situation is reversed in the above problem and you are the one that is moving, what would be the answer? (Remember right is positive.) See attached file for full pr

Ocean Depth

A sailor strikes the side of his ship just below the surface of the sea. He hears the echo of the wave reflected from the ocean floor directly 3.85 s later. How deep is the ocean at this point?

How Sound Travels and Pitch is Received

When a fast moving, pitched sound such as a siren travels towards and past me it's perceived pitch changes. Can you please explain what this is commonly known as and why this phenomenon occurs?

Pressure Waves

A hollow log, open at one end, is struck with a stout stick. The hollow cavity of the log is 6 meters long, and the pressure waves that constitute sound travel at 342m/s. What are the frequencies of the resulting first four harmonics?

A sound source is moving toward a microphone: Pulses, sound frequency

A sound source is moving toward a microphone at 25 m/s, emitting sound at a constant frequency of 740 Hz (i.e. 740 pulses per second). If the source starts out 5 meters from the microphone then: -how many pulses are emitted as the source approaches the microphone? -how long is it between the instant the microphone receives

Sound Waves

A steel guitar string has a length of 74 cm and thickness of 0.37 mm. It is under 35N tension. Calculate the wave speed in the string. The density of steel rho=7.84 x 10^3 kg/m^3.

Calculating the Frequency of Sound

A train is approaching a station and blows its horn with a frequency of 200hz. If the train has a speed of 25 m/s and the speed of sound is 350 m/s, what is the frequency of sound heard by the people standing on the platform a. 190hz b. 186hz c. 210 hz d. 200hz

Wavelength along a Cord

A cord is 20cm long, four complete waves fit along its length when vibrated 30 times per second for the waves on the cord. What is the wavelength? What is the frequency? What is the speed?

How far is the speaker from each observer?

A loudspeaker is placed between two observers who are 120m apart along the line connecting them. If one observer records a sound level of 60dB and the other records a sound level of 90dB, how far is the speaker from each observer?

Sound waves

A piano tuner hears one beat every 2.0s when trying to adjust two strings, one of which is sounding 440Hz. how far off in frequency is the other string?

Linear superposition, interference

(a) calculate the wavelengths in air at 20°C for sounds in the maximum range of human hearing, 20 Hz to 20,000 Hz. (b) what is the wavelength of a 10-MHz ultrasonic wave?

Linear superposition, interference

A hiker determines the length of a lake by listening for the echo of her shout reflected by a cliff at the far end of the lake. She hears the echo 1.5 s after shouting. Estimate the length of the lake.

Waves: Types and Speed

Question: A rope of mass 0.65 kg is stretched between two supports that are 30 m apart. If the tension in the rope is 120 N, how long will it take a pulse to travel from one support to the other? I am having trouble understanding this above question. Can you please explain this in a simple, non-confusing way.