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Pascal (Pa, n/m2) |
| The unit of pressure. It is used as a reference pressure for sound pressure levels. |
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Peak level (L peak, dB) |
| The highest sound pressure measured during a time period. This is the instantaneous pressure and not the rms (effective) pressure which is used for sound level and sound pressure level. This is measured using a sound level meter capable of measuring impact or impulse sounds which not every sound level meter is capable of doing. |
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Percentile |
| A distribution of numbers, the fraction (or percentage) of the distribution which exceeds the specified value. |
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Period (sec) |
| The length of time between repetitions of a periodic phenomena. The period is the reciprocal of frequency. Periods in acoustics are usually in fractions of a second. |
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Peak-to-peak (m[in.] |
| A vibration term for the total displacement of a vibrating surface. |
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PNC curves |
| A series of curves for rating sounds. The curves in increments of 5 units give in octave-band sound pressure levels for each curve. The curves have been published in the ASHRAE Guide and Data Book and are widely accepted. These curves superceded the NC curves. |
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Presbycusis (dB) |
| The gradual loss of hearing with age. The loss seems to differ between men and women. It is may be taken into account in some workers' compensation claims. It may be taken into account in evaluation of a threshold shift in an audiometric program. |
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Pure tone (f, Hz) |
| A sound which contains only one frequency. |
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