|Fill in the gray fields above, select the unit and click on the calculation button of the respective
column. Also the adjusted speed of sound c can be changed: 343 m/s or 1125.33 ft/s at 20°C.
When converting seconds to distance, the seconds have to be multiplied by 1000 and entered in the first field with the unit ms. The well known maximum value of the time difference (ITD) from ear to ear is 0.63 ms – and the strange "ear distance" that is believed to be 0.175 m = 17.5 cm.
Really? Do a calculation. c = r / Δ t r = Δ t × c Δ t = r / c r = distance
|Using the formula Δ t = r / c shows that the propagation of sound over a distance r in meters (m) is always connected to a time t in seconds (s). For example this correlation is important when calculating a delay line and using the Haas effect. Distance = time × velocity.|
In SI units with dry air at 20 °C (68 °F), the speed of sound c is 343 m/s.
This also equates to 1235 km/h, 767 mph, and 1125 ft/s.
The time duration of sound per meter (in air)
Effect of temperature on the time difference Δ t
Dependence of the speed of sound only on the temperature of the air
of air in °C
|Speed of sound
c in m/s
| Time per 1 m
Δ t in ms/m
Sound engineers take usually the rule of thumb:
For the distance of r = 1 m the sound needs about t = 3 ms in air.
Δ t = r / c and r = Δ t · c Speed of sound c = 343 m/s at 20°C,
equivalent to rounded 3 ms/m.
Temperature Dependence of Physical Quantities
Comb filter, Time delay Δ t and sound path r