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Solve delay in ms from a 0-500 m path difference and -40 to 60 C temperature, then classify it as direct-fusion, Haas, or echo with cutoffs at 1 and 40 ms.

📘 How to Use

  1. Enter the path difference in meters from the two sources to the listener
  2. Enter the air temperature of the room or venue in °C
  3. Read the delay in ms, the speed of sound, and the perceptual zone

Haas Effect Delay Calculator

m

Distance gap from the two sources to the listener position in meters.

°C

-40 to 60 C. Sound speed shifts with temperature so this is required.

※ Sound speed c = 331.3 + 0.606 T(C); delay = path difference / c.

※ Zone cutoffs: under 1 ms fuses, 1 to 40 ms is the Haas zone, 40 ms and above is heard as echo.

Delay
— ms
Speed of sound
— m/s
Perceptual zone
—

—

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Article

Haas Effect Delay Calculator | Turn a path difference into a precedence-effect zone

Drop in a path difference and a temperature, and this tool solves the delay in milliseconds with c = 331.3 + 0.606·T(°C), then tells you whether that delay lands in the direct-fusion, Haas, or echo zone. Built for dialing in stereo width and lining up live PA delay speakers.

💡 About this tool

If you mix, you have probably nudged a Haas delay to "around 15 ms" by feel and called the widening good enough. The catch is that the precedence effect switches behavior in stages: under-shoot or over-shoot the window and the image collapses, or the second copy peels off as an audible echo instead of width.

This calculator works backward from physics. Feed it the path difference between two arrivals and the air temperature, and it returns the delay plus the zone it falls into: under 1 ms the two copies fuse and only the image position moves, 1 to 40 ms is the Haas window where the image locks to the earlier source, and 40 ms and up the second copy separates as an echo. Because the speed of sound tracks temperature, a sweltering outdoor stage and an air-conditioned control room give different delays for the same distance, and the tool bakes that in.

🧐 Frequently asked questions

What delay range counts as the Haas effect? This tool treats 1 to 40 ms as the Haas window. Below 1 ms the copies fuse; above roughly 40 ms the ear starts hearing the second arrival as a separate echo. In practice, mixers often park stereo-width delays in the 5 to 30 ms region.

How do I measure the path difference? Measure the path length from each source (or each speaker) to the listening point separately, then enter the difference in meters. For live PA that is the distance gap from the main and delay speakers to a seat in the audience.

Why does temperature matter? The speed of sound rises with temperature: c = 331.3 + 0.606·T(°C). That is about 331 m/s at 0 °C, 343 m/s at 20 °C, and 349 m/s at 30 °C. The longer the outdoor delay run, the more a temperature swing shifts the timing.

Does a path difference of 0 give zero delay? Yes. No path difference means no arrival-time difference, and the result shows the direct-fusion zone.

📚 Where the 40 ms line comes from

The precedence effect is named after Helmut Haas, who formalized it in his 1949 doctoral work. When the same sound arrives twice with a small offset, the brain treats the first arrival as the source direction and folds the later copy in as reinforcement from that same direction. That single quirk underpins both stereo imaging and PA delay design.

Outdoors, temperature correction is not optional. The speed of sound shifts by roughly 0.18% per degree Celsius, so a delay speaker 30 m out drifts about 0.8 ms for every 5 °C change. That is why a delay line aligned during a warm afternoon soundcheck can be slightly off once the night cools down. Enter the temperature you expect at showtime and the estimate tightens up.