Sound Loops with Forever

Learning Goals 3 min

By the end of this lesson you will be able to:

1. Put a sound inside a forever loop to make it continuous.
2. Explain why the loop must use play sound [Meow v] until done rather than the other block.
3. Layer several looping sounds without them turning into noise.

Warm-Up 7 min

Your market makes all its noise in the first few seconds and then falls completely silent. Real places do not do that — there is always something going on underneath.

Quick-fire puzzle

Wei Jie wanted continuous background noise. He built this and got an unlistenable roar within about two seconds. What went wrong?

when flag clicked
forever
  start sound [Chatter v]
end
        

New Concept — a sound that restarts itself 15 min

You already know both halves of this. A forever loop runs its contents endlessly, and one of the two sound blocks waits while the other does not. Putting them together correctly is the entire lesson — and putting them together incorrectly is genuinely memorable.

Blocks reference

Why the boring block turns out to matter

Since Lesson 35 you have mostly reached for start-sound, because overlapping is what makes a market sound busy. Inside a forever loop that instinct is exactly wrong — the loop has no wait of its own, so the sound block has to supply one.

It is worth noticing that the same block can be the right answer and the wrong answer depending only on where it sits.

Loops from the Loops category

The sound library has a category called Loops, and those sounds are made for this. They are recorded so the end joins seamlessly onto the beginning, which means a forever loop plays them as continuous music rather than an obvious repeat.

Any sound will loop, but most will have an audible seam. If you want background that nobody notices, start there.

Layering background

Different sprites can each run their own looping sound, and because they are separate scripts the loops overlap without fighting. Two or three layers is usually plenty — beyond that it stops being atmosphere and becomes noise.

Why it matters

Continuous background is what makes a soundscape feel like a place rather than a sequence of effects. It is also how nearly every game gets its music.

Worked Example — the market that keeps humming 15 min

We make the mistake first, on purpose, because it is much easier to remember once you have heard it.

Step 1 — Make the mistake

On the stall sprite, build the wrong version and run it for about two seconds before hitting the stop sign.

when flag clicked
forever
  start sound [Chatter v]
end
        

Step 2 — Work out why

The loop has nothing to slow it down, so it goes round as fast as the computer allows, starting a new copy of the sound every single time. Within a second there are hundreds playing at once.

Step 3 — Fix it with the waiting block

Swap the sound block for the until-done version and run it again.

when flag clicked
forever
  play sound [Chatter v] until done
end
        

Step 4 — Push it into the background

At full volume the loop competes with everything else. Set it lower before the loop begins.

when flag clicked
set volume to (35) %
forever
  play sound [Chatter v] until done
end
        

Step 5 — Add foreground sounds over the top

On the cat, keep using start-sound for one-off noises. Because it is a different sprite and a different script, it plays cleanly over the background.

when flag clicked
set volume to (100) %
wait (2) seconds
start sound [Murah v]
wait (3) seconds
start sound [Murah v]
        

Step 6 — Listen for the seam

Focus on the background and wait for the moment it restarts. If you can hear a click or a gap, the sound was not designed to loop. Try something from the Loops category instead and the seam disappears.

Step 7 — Add a second layer

Give a third sprite its own looping sound at a different volume. Two layers of background, at different distances, is where a market starts sounding genuinely convincing.

Step 8 — Check it stops

Press the stop sign. Everything should go silent immediately. A forever loop has no ending of its own, so the stop sign is currently the only way out — which is fine for background music, and worth being aware of.

What changed: your market has an underneath. It no longer runs out of noise after five seconds.

The full assembled scripts (your reference)

when flag clicked
set volume to (35) %
forever
  play sound [Chatter v] until done
end

when flag clicked
set volume to (100) %
wait (2) seconds
start sound [Murah v]
        

Try It Yourself — three small builds 12 min

when flag clicked
set volume to (30) %
forever
  play sound [Chatter v] until done
end
          

when flag clicked
set volume to (50) %
forever
  play sound [Bell Toll v] until done
  wait (2) seconds
end
          

Mini-Challenge — the seam hunt 5 min

“Find the join”

Build a looping background and find out whether a listener can hear the moment it restarts. Then find a sound where they cannot.

It works if:

• You loop an ordinary sound and can point out exactly when it restarts.
• You loop something from the Loops category and cannot.
• You can describe what the seam sounded like.
• Your final background uses the seamless one.

Recap 2 min

A sound inside a forever loop becomes continuous background — but only with play sound [Meow v] until done, because the loop has no wait of its own. The start-sound block that has served you well everywhere else produces hundreds of overlapping copies here. Add a wait inside the loop and the background becomes a rhythm instead of a drone, and keep background volumes well below your foreground sounds or nothing else can be heard.

Looping sound

A sound inside a forever loop, restarting each time it ends.

Loops category

Library sounds recorded so the end joins the start with no audible seam.

Seam

The audible join where a looping sound restarts.

Layering

Several sounds at different volumes, creating foreground and background.

Homework 1 min

The minute test. Find out how long your background survives before it becomes annoying.

1. Build a looping background and leave it running for a full minute.
2. Write down the moment you first noticed the repeat.
3. Try a longer sound, or a second layer, and see whether that moment gets later.
4. Screenshot your final script.

when flag clicked
set volume to (30) %
forever
  play sound [Chatter v] until done
end
        

Bring back next class:

• Your two timings, before and after.
• Your answer to: “Why does start sound produce chaos inside a forever loop when it works perfectly well outside one?”

Heads up for next class: SCR-L01-39 is the arc finale. You assemble the whole soundscape and save it to show.