Freezing sound into numbers

Computing · Computer Systems · ages 14-16

Name ______________________ Date ____________

In a music file, 44,100 counts the samples stored each second.
Circle one: True False
What is a sample of a sound?
- The whole song
- One measure
- A speaker
How does sound travel through air?
- As light rays
- As silent bits
- Pushes, pulls
What does a lower sample rate cost?
- Detail; the copy drifts
- Volume only, the shape stays perfect
- Nothing at all
What does a higher sample rate give you?
- The same copy in a bigger file
- A closer copy in a bigger file
- A closer copy in a smaller file
What does bitrate count?
- Songs on an album
- Bits each second
- Speakers in the room
Nadia claims her file holds every point of the wave. What is off?
- No file stores the gaps
- Files hold waves fully
- Only some file types have gaps
Why can a digital recording never hold the whole wave?
- Samples play back too fast
- Smooth wave, stepped samples
- Speakers refuse smooth sound

Answer key

For grown-ups. Fold this page away before handing over the rest.

True · That count is the sample rate: measurements per second.
One measure · Each sample records the wave height at one tiny step.
Pushes, pulls · Pushes and pulls bunch the air outward, and the pattern carries the energy.
Detail; the copy drifts · Fewer steps mean a rougher copy that misses the wave wiggles.
A closer copy in a bigger file · More steps track the wave better, and every step costs storage.
Bits each second · Bitrate is bits per second, and higher keeps more detail.
No file stores the gaps · Every recording skips the gaps, so no file holds it all.
Smooth wave, stepped samples · Infinitely detailed waves cannot fit into finite stored steps.