A gathering hall is designed to filter noise from traveling outside by absorbing it. Suppose the walls of the hall decrease the sound intensity level by 25 dB. Determine the fraction by which the walls lower the sound intensity in W/m².

An alarm emits sound waves at a frequency of 520 Hz. The air has a temperature of 17.8° C. The wave has an amplitude of 6.00 × 10^-3 mm. What is the pressure amplitude of this wave (in Pa)?

Sound is recorded by a microphone using the vibrations caused by the sound on a diaphragm. If a microphone has a diaphragm diameter of 12.7 mm, how much energy does a singer singing at 90 dB supply to the diaphragm?

A vessel contains a 20. cm high column of water and a layer of carbon tetrafluoride of unknown thickness (the two layers do not mix). A high-frequency sound wave propagates vertically into the liquids. The ratio N_w/N_T = 0.83 (#cycles in water to #cycles in carbon tetrafluoride). Find the thickness of the carbon tetrafluoride layer. Take the speed of sound in water as 1493 m/s and in carbon tetrafluoride as 930 m/s.

Cats employ sound localization techniques to catch mice. Cats can determine the direction of the sound source, the mouse, thanks to variations in the sounds that reach their auditory system (for instance, differences in the sounds' arrival times). Consider a mouse gnawing 3.0 m away from the center of the cat's head, along a line 30° to the left. Find the difference in the arrival time of the sound of gnawing. The distance between the cat's left and right ears is 7.0 cm. Assume a room temperature of 20 °C.

A longitudinal sound wave generated by an ultrasonic emitter travels along a 3.50 m copper rod in 1.00 ms. The volume of the rod is 1.116 × 10^-4 m³ and its mass is 1.00 kg. What is Young's modulus (Y) for copper?

A nylon guitar string vibrates according to the equation y = 0.2 sin(2.28 x)sin(40π t) where x and y are in cm and t in seconds. What is the amplitude A of the two transversal waves that form this standing wave pattern?

A second harmonic is generated in an elastic cord of length l stretched between two clamps. The vertical displacement (y) of a cord element as a function of the horizontal position x and time t is given by the equation  . Make a sketch of the standing-wave pattern.

A copper cable is tied between two trees. The horizontal distance between the two trees is 3 m. The transverse waves travel at a speed of 80 m/s along the taut cable. Calculate the i) wavelength and ii) frequency of the third overtone.

A physicist uses a 40 cm plastic line with a linear density of 0.3 g/m to create sounds by making the line vibrate. The physicist tests the instrument in a lecture hall by making the line vibrate in its fundamental mode. The temperature in the hall was 20°C. The students in the hall catch a sound with a wavelength of 50 cm. Calculate the tension in the line.