Calculate speaker delay from distance or time-align two speakers using temperature-adjusted sound speed, with feet, meters, milliseconds, and sample counts.

Enter the sound-travel distance or extra acoustic path.

Approximate dry-air model. Accepted range: −80°C to 80°C (−112°F to 176°F); accuracy is lower at the extremes. Verify alignment acoustically at the intended listening position.

Speaker Delay Formula

The following formula is used to calculate a speaker delay.

D = X / S × 1000
  • Where D is the delay (ms)
  • X is the distance from the source (ft)
  • S is the speed of sound (ft/s)
    • The calculator approximates dry-air speed as c = 331.3 + 0.606 × T°C in m/s. At 20°C (68°F), c ≈ 343.42 m/s or 1126.706 ft/s. This linear model is less accurate at temperature extremes.

To calculate sound-travel delay, divide path distance by sound speed and multiply by 1000 for milliseconds. For alignment, measure both speaker-to-listener paths to the same position and use their absolute difference; delay the nearer speaker. Reverse mode multiplies delay in seconds by sound speed to find distance. The temperature formula is the rough dry-air approximation given in the NC State/AIS sound-speed lab.

What is Speaker Delay?

Definition:

Speaker delay is a measure of the total time it takes sound to travel from a speaker to a certain location.

How to Calculate Speaker Delay?

Example Problem:

The following example outlines how to calculate a speaker delay.

First, determine the distance from the speaker. In this example, the person is standing 500 feet from the source speaker.

Next, use an air temperature of 20°C (68°F). The calculator’s linear model gives 343.42 m/s, approximately 1126.706 ft/s.

Finally, calculate the speaker delay using the formula above:

D = X / S * 1000

D = 500 / (343.42 / 0.3048) × 1000

D ≈ 443.771 milliseconds (ms). This is a sound-travel estimate for 500 ft, not automatically the alignment delay between two speakers.

FAQ

What factors can affect the speed of sound and thus the speaker delay?

Temperature and gas composition, including humidity, affect sound speed. In the ideal-gas model, lower pressure and density at altitude do not alone reduce sound speed at a fixed temperature. Altitude can affect it through changes in temperature. NASA explains the temperature dependence. This calculator uses a dry-air temperature approximation and does not model humidity.

How does speaker delay impact the listening experience in large venues?

For speakers at different distances from a chosen listening position, geometric alignment delays the nearer speaker by the difference in sound-travel times. This can reduce arrival-time differences at that position, but a single delay setting cannot guarantee synchronized arrivals or a particular listening experience throughout a venue. Verify the result with acoustic measurements and account for loudspeaker and DSP latency.

Can speaker delay be adjusted for outdoor events?

Outdoor alignment should be checked at the intended listening position. Wind and temperature gradients can change propagation, and speaker or DSP latency can add electronic delay. The geometric calculation is a starting estimate and cannot guarantee alignment throughout an audience area. Any extra localization offset is a separate choice; see QSC’s delayed-loudspeaker guidance.