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Threshold of hearing (dB) |
| The lowest sound pressure level that can be heard by a young person who has had no problems with their hearing. The threshold of hearing is a function of frequency; the sound pressure level is higher at low frequencies and about 0 dB around 1000 Hz. |
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Threshold shift |
| The change in hearing level between two consecutive audiograms. It is determined at each of the audiometric test frequencies; sometimes it is averaged over several frequencies. |
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Transmission loss |
| (see Sound transmission loss) |
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Transmissibility |
| A measure of the effectivness of a vibration isolator or hanger. The smaller the transmissibility the better the vibration isolation. It is the ratio of the vibration input to the top of the isolator to the output at the bottom of the isolator. |
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Triple wall resonance |
| The same as a double wall resonance (which see) except there are three surfaces and two air spaces resulting in several resonances. |
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Time-weighted average (TWA, dB) |
| The average noise exposure of a person computed from the measured time-varying sound levels |
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TWA |
| (see Time-weighted average) |
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