Audio Engineering

42 Chapter 2 The power output of Boulder Dam is said to be approximately 3,160,000,000 W. Expressed in dBm, this output would be ...

Measurement 43 The root mean square (rms) sound pressure P can be found by PfAcrms 2 πρ, (2.20) where Prms is in pascals, f is ...

44 Chapter 2 2.6 Acoustic Intensity Level ( LI), Acoustic Power Level ( LW ), and Acoustic Pressure Level ( LP ) 2.6.1 Acoustic ...

Measurement 45 2.6.2 Acoustic Power Level, L W The total acoustic power can also be expressed as a level ( LW ): L Total acousti ...

46 Chapter 2 2.7 Inverse Square Law ............................................................................................ ...

Measurement 47 This effect is commonly called the inverse square law change in level. Gravity, light, and many other physical ef ...

48 Chapter 2 2.10 A Decibel is a Decibel is a Decibel ......................................................................... ...

Measurement 49 being measured). For 1 W using 10 ^12 W at 0.283 m, LW  LP  120 dB. For 1 W using 10 ^13 W at 0.282 ft, LW  ...

50 Chapter 2 Table 2.5 : Preferred Reference Labels for Acoustic Name Defi nition Sound pressure squared level LP  20 log ( p / ...

Measurement 51 2.12 The Equivalent Level (LEQ) in Noise Measurements .............................................. Increasingly ...

52 Chapter 2 certain period of time such as 90 dBA for 3.6 s (this could be a series of levels that lasted seconds, hours, or ev ...

Measurement 53 This integration reduces to LEQ 10 10 3 6 3600 (^9010) log .s s . ⎛ ⎝ ⎜⎜ ⎜⎜⎜ ⎞ ⎠ ⎟⎟ ⎟⎟ ⎟ Thus 1.0 hour of noise ...

54 Chapter 2 LDN (day–night level), CNEL (community noise level), and so on all follow similar schemes with variation in weighti ...

Measurement 55 An alternative dB addition technique is given through the courtesy of Gary Berner. LT smallest number diff in dB ...

56 Chapter 2 and the noise combined ( LSN ). Then take another reading of the noise alone (the source having been shut off). Th ...

Measurement 57 2.13.4 To Add Levels Enter the chart with the numerical difference between the two levels being added (top of cha ...

58 Chapter 2 Example Subtract 81 dB from 90 dB; the difference is 9 dB. The 9-dB vertical line intersects the curved line at 0.6 ...

Measurement 59 Example We have a 100 W amplifi er but plan to use a 12-dB margin for “ head room. ” How many watts will our prog ...

60 Chapter 2 Example A loudspeaker has a sensitivity of LP  99 dB at 4 ft with 1 W of input power. What will the level be at 10 ...

Measurement 61 Suppose we want to fi nd the natural logarithm of 2 (written ln 2). The base of natural logarithms ise  2.718828 ...