during cost analysis you will also compare the proposed cost elements with i actual costs ii previous cost estimates for same or similar work iii other cost estimates iv independent government estimates and v forecasts of planned expenditures
How Decibels Apply to Music and Sound. In music, decibels are a measurement of Sound Pressure Level (SPL). When we say the speakers at a rock concert are playing at 110dB, what we really mean is that theyâre playing at 110dB SPL. Since the decibel is only a ratio, 110dB is actually a comparison to a different number: 0 SPL.
The solution to these problems is the decibel scale. Here's how the decibel scale works. The level at which a sound becomes audible to a young, average, healthy ear is designated as zero decibels (0dB). 1. Every increase of 3 dB is a doubling of the sound pressure level (twice as many micropascals). A sound of 23 dB is twice as much energy as a sound of 20 dB. 2. Every increase of 10 dB is a tenfold increase. A sound of 30 dB is ten times as loud as 20 dB, and 100 times as loud as 10 dB. 3. Conversational speech is at about 60-70 dB; a whisper is around 20 dB. 4. The decibel scale is actually a pretty accurate representation of how the human auditory system perceives sound. In reality, a 40 dB sound is 100 times as loud as a 20 dB sound, but it seems twice as loud. Twice as loud as 20 dB is actuallly 23 dB, but it doesn't really seem that way.