In Metrology, dead space or threshold is a static characteristic of an instrument defined as the range of different input values over which there is no change in output value.
If the instrument input is increased very gradually from zero there will be some minimum value below which no output change can be detected. This minimum value defines the threshold of the instrument.
The numerical value of the input to cause a change in the output is called the threshold value of the instrument.
- Threshold of hearing