Volume & Pitch Effects

Learning Goals 3 min

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

1. Use set volume to (50) % and change volume by (-10) to make a sound louder or quieter.
2. Use change [pitch v] effect by (50) to raise or lower the pitch of a sound.
3. Use clear sound effects to reset the sprite's sound effects to normal.

Warm-Up 7 min

Last lesson you chose the pasar pagi sounds. Today you'll shape them — quieter, louder, squeakier, deeper — so your market feels alive.

Quick-fire puzzle

Priya wrote this script. She clicked the green flag. The cat meowed twice. What was different between meow one and meow two?

when flag clicked
set volume to (100) %
play sound [Meow v] until done
set volume to (30) %
play sound [Meow v] until done
        

New Concept — volume and pitch 15 min

Think of a sprite's volume like a TV remote. Set volume to 50 % punches in a number. Change volume by -10 presses the volume-down button. Pitch is similar — it changes how high or low a sound feels, like helium for the cat (high pitch) or a deep cave echo (low pitch).

Today's new blocks

How the numbers work

• Volume goes from 0 (silent) to 100 (full). Above 100 still plays at 100. Below 0 still plays at 0.
• Pitch is an effect that stacks. Each change pitch by 50 adds 50 more. Two of them = +100 (much squeakier). Negative numbers go the other way — deep voice.
• clear sound effects wipes pitch back to 0 but does NOT touch volume.

A worked stack to study

when flag clicked
set volume to (100) %
play sound [Meow v] until done
change volume by (-50)
play sound [Meow v] until done
change [pitch v] effect by (80)
play sound [Meow v] until done
        

Why it matters

Real projects need variety. A big monster should sound deep. A cute baby chick should sound squeaky. A faraway noise should sound quiet. With three Sound effect blocks you can make one sprite sound like ten different characters — without recording any new audio.

Worked Example — the fading meow 15 min

Open Scratch with the cat selected. We'll build a five-meow sequence where each meow is quieter than the last — a cat walking away into the distance.

Step 1 — Start with a hat

Drag when flag clicked into the Script Area.

Step 2 — Lock the starting volume

Click the pink Sound category. Drag set volume to (100) % under the hat. This guarantees the first meow is at full volume — no matter what an earlier project left behind.

Step 3 — First meow (loud)

Drag play sound [Meow v] until done under the volume block.

when flag clicked
set volume to (100) %
play sound [Meow v] until done
        

Step 4 — Turn the volume down by 20

Drag change volume by (-10) under the play-sound block. Click the white circle and change -10 to -20.

Step 5 — Second meow (a bit quieter)

Drag another play sound [Meow v] until done below. Now the volume is 80 — slightly quieter.

Step 6 — Repeat the pattern

Drag a third change volume by -20 and a third meow. The volume is now 60. Add one more pair — volume drops to 40. Click the green flag.

Four meows. Each quieter than the last. The cat sounds like it's walking away.

What changed: compared to last lesson, you no longer just play a sound — you shape it. One block of variety per repeat and your scene gets richer.

The full assembled stack (your reference)

when flag clicked
set volume to (100) %
play sound [Meow v] until done
change volume by (-20)
play sound [Meow v] until done
change volume by (-20)
play sound [Meow v] until done
change volume by (-20)
play sound [Meow v] until done
        

Try It Yourself — three small builds 12 min

when flag clicked
set volume to (50) %
play sound [Meow v] until done
          

when flag clicked
clear sound effects
change [pitch v] effect by (100)
play sound [Meow v] until done
change [pitch v] effect by (-200)
play sound [Meow v] until done
        

when flag clicked
clear sound effects
set volume to (30) %
play sound [Meow v] until done
change volume by (15)
change [pitch v] effect by (-30)
play sound [Meow v] until done
change volume by (15)
change [pitch v] effect by (-30)
play sound [Meow v] until done
change volume by (15)
change [pitch v] effect by (-30)
say [I am the monster cat!] for (2) seconds
          

Mini-Challenge — the helium cat 5 min

"Squeaky greeting"

Build a script where the cat says "Selamat datang!" out loud (using a recorded clip from L01-36 if you have one, otherwise the cheer library voice) — but at a very high pitch. Bonus: after the greeting, reset everything so the next meow sounds normal.

It works if:

• The greeting plays at noticeably higher pitch than normal.
• After the greeting, a follow-up meow sounds normal — same pitch and volume as a fresh Scratch project.
• You use today's blocks (set/change volume, change pitch, clear sound effects) combined with last lesson's sound choice.

when flag clicked
set volume to (100) %
change [pitch v] effect by (100)
play sound [cheer v] until done
clear sound effects
play sound [Meow v] until done
          

Recap 2 min

Today you learnt to shape sounds, not just play them. Volume controls how loud; pitch controls how high or low. Both stick around until you change them. Clear sound effects resets pitch back to normal — useful at the top of every script that uses pitch.

Volume

How loud a sprite's sounds play. Range: 0 (silent) to 100 (full). Sticks until changed.

Pitch

How high or low a sound feels. Positive = squeaky. Negative = deep. Stored as an effect amount.

change vs set

Set picks a fixed number (e.g. 50 %). Change adds to the current number (e.g. -10 makes it 10 less than now).

clear sound effects (block)

Resets pitch and pan effects to zero. Does NOT reset volume.

sound effect

A modifier applied to every sound the sprite plays. Pitch and pan are the two effects in Scratch.

Homework 1 min

Cat to mouse to lion. Build one script that plays the meow three times, but the cat sounds different each time: first normal, second like a tiny mouse (high pitch + quiet), third like a roaring lion (deep pitch + loud).

1. Start with clear sound effects and set volume to (100) % so the first meow is the baseline.
2. Adjust volume and pitch between the meows to morph the voice.
3. Test it. Tweak the numbers until the three meows really do feel like cat, mouse, and lion.

when flag clicked
clear sound effects
set volume to (100) %
play sound [Meow v] until done
set volume to (30) %
change [pitch v] effect by (120)
play sound [Meow v] until done
set volume to (100) %
change [pitch v] effect by (-200)
play sound [Meow v] until done
        

Bring back next class:

• A screenshot of your Script Area.
• Your own numbers — what volume and pitch felt the most "mouse-like" and "lion-like" to you?

Heads up for next class: SCR-L01-38 wraps a Sound block in forever to make a continuous background loop — your first drumbeat.