5. The noise level caused by a compressor located outdoors is 77 dB at 20 m....
The noise level due to a compressor located outdoors is 89 dB at 15 m with no intervening structures. Estimate the level at 60 m if the compressor is located 2 m from a large building wall 8.
Fifty machines in a room produce a noise level of 100 dB (re 20 μPa). Using the exact method, answer the following: a. If 20 machines are removed, what will be the new noise level in the room? b. If in place of 20 machines, 25 machines are removed, calculate the new noise level. c. Would you recommend removing the additional five machines (part b)? Why or why not?
vi) The random noise level of a buzzing bee is 42 dB and that heard in a typical beehive is 78 dB. How many bees are there in the bee hive ? (3) 41(2): 10 lo7 (2) Itoy = n I, vii) What is the charge to mass ratio (C/kg) when an ion with unknown charge and mass has moved through a potential of 10 kV and is observed to move in an 84 cm radius circular orbit perpendicular to...
. At your apartment, you hear the busy road (the dB level of a freeway is 80 dB from 1.00 m away) and measure the noise at a constant level of 45 dB. a) What is the power output of traffic on the road? b) How far away is your house from the road? c) How far from the road would you need to be for the sound to measure at 20 dB? d) Town Hall is planning to add...
At your house, you hear the busy freeway (the dB level of a freeway is 80 dB from 1.00 m away) and measure the noise at a constant level of 45 dB. A. What is the power output of traffic on the freeway? B. How far away is your house from the freeway? C. How far from the freeway would you need to be for the sound to measure at 20 dB? D. Town Hall is planning to add panels...
The decibel level of the noise from a jet aircraft is 130 dB when measured 24.8 m from the aircraft. How much sound power does the jet aircraft emit? Answer in units of W. How much sound power would strike the eardrum of an airport worker 24.8 m from the aircraft? Assume the diameter of the worker’s eardrum is 1.7 × 10−2 m. Answer in units of W.
7. Sound pressure level measurements were taken in a semi-anechoic chamber at 5 m from the source. A ten point hemispherical array was utilized in this process. The following data was obtained: (1) L,-94 dB, (2) Lp-96 dB, (3) L,-97 dB, (4) L,-93 dB, (5) Lp-92 dB, (6) L,-90 dB, (7) L,-91 dB, (8) L,-95 dB, (9) L,-93 dB, (10) Lp-94 dB From these values a) Determine the sound power level of the noise source b) The maximum directivity index...
Question # B.5 signal power-level at the coresponding change in is signal power-level at the input is kept constant? Is C a linear function of temperature? Justify (a) In a communication system, suppose the associated operating temperature is doubled. Then, what is the corresponding change in the system capacity (C), if the (b) A mixer-stage in a radio receiver has a NF-20 dB and this mixer-stage is preceded by a preamplifier with a NF 9 dB. The available power-gain ratio...
An air compressor used in a large car body shop is located in an inside equipment room. Fresh air at 5 ºC, 96 kPa is conveyed to the compressor from outside through a 30-cm circular duct that is 15-m long. The duct runs along the ceiling of the facility where the temperature is 34 ºC. If the air flow rate is 0.35 m3 /s, determine: a. the temperature of the air when it reaches the compressor (in ºC) b. the...
12 oblem # 6 The front-endof has a a radio receiver has a preamplifier followed by a mixer stage. The mixer stage with lactorN2-100 and the pre amplifier has NF, 9 dB. The overall noise factor of the 11.04. Suppose a signal of power-level equal to 5 dBm is watts,h imput of the preamplifier. Determine the output power-level of the preamplifier in Useful hint-Friis formula: SOLUTION
12 oblem # 6 The front-endof has a a radio receiver has a preamplifier...