Q1) A cicada can produce a sound intensity level of 105 dB at a distance of 0.5 m. How far must you stand for the cicada's noise to drop to the level of a whisper (20 dB)? A. 3 km B. 5 km C. 7 km D. 9 km

(a) What are the loudnesses in phons of sounds having frequencies of 200, 1000, 5000, and 10,000 Hz. if they are all at the same 60.0dB sound intensity level? (b) If may are all at 110 dB? (c) If they are all at 20.0 dB?

Write an expression that describes the pressure variation as a function of position and time for a sinusoidal sound wave in air. Assume the speed of sound is 343 m/s, = 0.100 m, and Pmax = 0.200 Pa.

Air temperature in the Sahara Desert can reach 56.0°C (about 134°F). What is line speed of sound in air at that temperature?

(a) How much more intense is a sound that has a level 17.0 dB higher man another? (b) If one sound has a level 23.0 dB less than another, what is the ratio of their intensi?es?

(a) What frequency is received by a person watching an oncoming ambulance moving at 110 km/h and emitting a steady 800—Hz sound from its siren? The speed of sound on this day is 345 m/s. (b) What frequency does she receive after the ambulance has passed?

Consider a diagnostic ultrasound of frequency 5.00 MHz that is used to examine an irregularity in soft tissue. (a) What is the wavelength in air of such a sound wave if the speed of sound is 343 m/s? (b) If the speed of sound in tissue is 1800 m/s, what is the wavelength of this wave in tissue?

(a) Ear trumpets were never very common, but they did aid people with hearing losses by gathering sound over a large area and concentrating it on the smaller area of the eardrum. What decibel increase does an ear trumpet produce it its sound gathering area is 900 cm2 and the area of the eardrum is 0.500 cm2, but the trumpet only has an eficiency of 5.00% in transmitting the sound to the eardrum? (b) Comment on the usefulness of the decibel increase found in part (a).

A driver travels northbound on a highway at a speed of 25.0 m/s. A police car, traveling southbound at a speed of 40.0 m/s, approaches with its siren producing sound at a frequency of 2 500 Hz. (a) What frequency does the driver observe as the police car approaches? (b) What frequency does the driver detect after the police car passes him? (c) Repeat parts (a) and (b) for the case when the police car is behind the driver and travels northbound.

A family ice show is held at an enclosed arena. The skaters perform to music playing at a level of 80.0 dB. This intensity level is too loud for your baby, who yells at 75.0 dB. (a) What total sound intensity engulfs you? (b) What is the combined sound level?