§ 17
How many milliseconds should the delay speaker be delayed?
Answer: At large events, there are delay speakers out in the audience, so those at the back can hear. The delay speaker must be delayed so its sound arrives at the same time as or slightly after the sound from the main system. Otherwise the audience hears an echo, and the sound seems to come from the delay tower. The calculator works out the travel time from the distance and temperature and adds a little extra allowance.
Lydens hastighed c = 331,3 + 0,606 × T (T i °C)
Gangtid = afstand / c
Forsinkelse = gangtid + tillæg
The allowance uses the precedence effect: when the main system's sound comes a few milliseconds before, the ear perceives the sound as coming from the scene.
| Symbol | Meaning | Unit |
|---|---|---|
| afstand | Distance from main system to delay loudspeaker | m |
| temp | Air temperature | °C |
| tillaeg | Extra add-on so the main system is heard first | ms |
| fs | Sample frequency in processor | — |
| = | Delay to be set | ms |
| = | Sound travel time from main facility to delay | ms |
| = | Sound speed at the temperature | m/s |
| = | Delay in samples | samples |
Does not apply when
The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.
Substituted
Giver
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Når en udendørs koncert eller en stor sal har delay-højttalere ude blandt publikum, skal de forsinkes, så lyden fra hovedanlægget og delayet kommer samtidig hos publikum. Beregneren regner gangtiden ud fra afstanden og temperaturen og lægger et lille tillæg til, så lyden opleves som kommende fra scenen.
Et delay-tårn står 40 m fra hovedanlægget en sommereftermiddag ved 20 °C. Du bruger 10 ms tillæg i en processor på 48 kHz.
It means: Lyden bruger 116.5 ms om at nå delay-tårnet. Indstil forsinkelsen til 126.5 ms, svarende til 6,071 samples.
Om aftenen er det kun 8 °C. Et delay står 60 m fra hovedanlægget, og du bruger 15 ms tillæg.
It means: Lydens hastighed er faldet til 336.1 m/s, så forsinkelsen skal være 193.5 ms.
Under balkonen i et teater sidder små højttalere 12 m fra hovedanlægget. Salen er 22 °C, og du bruger 5 ms tillæg.
It means: Forsinkelsen skal være ca. 39.8 ms.
Lyden bruger ca. 3 ms pr. meter. 40 m er ca. 117 ms.
Mål med et analyseprogram og en mikrofon midt mellem hovedanlæg og delay. Impulssvarene skal ligge, som du har indstillet.