| Meter | Delay in msec | ||
| 3.4 mm | 0.01 | ||
| 6.8 mm | 0.02 | ||
| 34 mm | 0.10 | ||
| 340 mm | 1.00 | ||
| Meter | Delay in msec | Feet | Delay in msec |
| 3.40 | 10 | 20 | 17.9 |
| 5 | 14.6 | 30 | 26.8 |
| 10 | 29.2 | 40 | 35.7 |
| 15 | 43.8 | 50 | 44.6 |
| 20 | 58.5 | 60 | 53.6 |
| 25 | 73.1 | 70 | 62.5 |
| 30 | 87.7 | 80 | 71.4 |
| 34 | 100 | 90 | 80.4 |
| 35 | 102.3 | 100 | 89.3 |
| 40 | 117.0 | 110 | 98.2 |
| 45 | 131.6 | 120 | 107.1 |
| 50 | 146.2 | 130 | 116.1 |
| 55 | 160.8 | 140 | 125.0 |
| 60 | 175.4 | 150 | 133.9 |
| 65 | 190.1 | 160 | 142.9 |
| 70 | 204.7 | 170 | 151.8 |
| 75 | 219.3 | 180 | 160.7 |
| 80 | 233.9 | 190 | 169.6 |
| 85 | 248.5 | 200 | 178.6 |
| 90 | 263.2 | ||
| 95 | 277.8 |
The audible echo or delay results in the time difference of the arrival of the sound from the source and the sound reflected on a reflective surface. Because the audible sound from the source is delayed already by the travelling distance from the source to the listener, the audible echo is created just by the travel distance between the listener and the surface and back to the listener! The closer one is standing to the reflecting surface the shorter is the audible echo. The audible echo is always longest at the source position.
An artist on stage is hearing the echo from the rear wall of a concert hall with the longest delay, in the audience this echo is getting shorter the further back one is sitting. The echo from the rear wall is inaudible directly at the rear wall.
Audible echo or delay time is always depending on the distance to the reflective surface and not depending on the distance to the sound source.
