An interface is formed between a block of aluminium (with an acoustic impedance of 1.8 x 107 kg m2 s') and a block of copper (with an acoustic impedance of 4.6 x 107 kg m-2 s-1). Longitudinal sound waves travelling through the aluminium are normally incident on the boundary, and are partially reflected. a) What is the ratio of the amplitude of the reflected wave to that of the incident wave? Number b) What is the ratio of the amplitude of the transmitted wave to that of the incident wave? Number c) What percentage of the incident power is transmitted? Number d) What percentage of the incident power is reflected? Number % Ouit P Sove Questi

The speed of sound in dry air at 20 °C is 343 m/s and the lowestfrequency sound wave that the human ear can detect is approximately20 Hz. (a) What is the wavelength of such a soundwave?

Problem 6:  An audio engineer takes decibel readings at distances of r1 = 14 m and r2 = 25 m from a concert stage speaker during a sound check. When he is r1 from the speaker, the engineer registers a decibel level of β1 = 110 dB on his loudness meter.Randomized Variables r1 = 14 mr2 = 25 mβ1 = 110 dB       Part (a) What is the intensity of the sound, I1, in watts per square meter, that is measured by the loudness meter when the engineer is a distance of r1 from the speaker?Numeric   : A numeric value is expected and not an expression.I1 = __________________________________________Part (b) How much power P, in watts, is coming from the speaker during the sound check at distance r1?Numeric   : A numeric value is expected and not an expression.P = __________________________________________Part (c) Assuming that the speaker output does not change between the two measurements at r1 and r2, what sound intensity level β2, in decibels, will the loudness meter report when the…

Find the range of wavelengths emitted by the bat in meters, by using that the speed of sound is c=343m/sec and the range of frequencies from 70 to 30KHz. The solution matches the range of sizes for an insect. What is the order of magnitude for this range? Take this order and call it  L for the average size of an insect. b) If the bat produces a power of P = 10^-5 watts and its hearing threshold is  10^-12 watts/m^2 what is the maximum distance from which the bat can detect an echo?

A sound wave at 80 dB has an intensity of 10^-4 W/m^2.  How much, Power, in Watts, does that sound wave exert over a 10 m by 10 m square?

Problem 3:  The human ear can detect a minimum intensity of Io = 10-12 W/m2, which has a sound intensity of 0 dB.Randomized Variables β = 45 dB       If the student hears a sound at 45 dB, what is the intensity of the sound?Numeric   : A numeric value is expected and not an expression.I = __________________________________________   Problem 4:  A student exchanges the stock headphones (β1 = 87 dB) for her mp3 player for a new set that is louder (β2 = 95 dB).       If the first set produced a power of P1 = 0.5 W how much power does the new set produce, P2 in W?Numeric   : A numeric value is expected and not an expression.P2 = __________________________________________

(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 if its sound gathering area is 900 cm2 and the area of theeardrum is 0.500 cm2 , but the trumpet only has an efficiency of 5.00% in transmitting the sound to the eardrum?(b) Comment on the usefulness of the decibel increase found in part (a).

Problem 7:   An audio engineer takes decibel readings at distances of r1 = 11 m and r2 = 25 m from a concert stage speaker during a sound check. When he is r1 from the speaker, the engineer registers a decibel level of β1 = 103 dB on his loudness meter.Randomized Variables r1 = 11 mr2 = 25 mβ1 = 103 dBPart (a)  What is the intensity of the sound, I1, in watts per square meter, that is measured by the loudness meter when the engineer is a distance of r1 from the speaker?  Part (b)  How much power P, in watts, is coming from the speaker during the sound check at distance r1?  Part (c)  Assuming that the speaker output does not change between the two measurements at r1 and r2, what sound intensity level β2, in decibels, will the loudness meter report when the engineer is at a distance r2 from the speaker?

The frequency separating audible waves and ultrasonic waves is considered to be 20 kHz. What wavelength in air at room temperature is associated with this frequency? (Assume the speed of sound to be 340 m/s.)