Effect of sample rate and resolution on accuracy and file size

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Quick Questions

Shade in the A or B circle for each question.

1. A student raises the sample rate of a recording. What happens to the file size?

A It gets larger because more samples are stored

B It gets smaller because the sound is cleaner

2. Which recording is MORE accurate to the original sound wave?

A A recording with a high sample rate

B A recording with a low sample rate

3. A sound is recorded with a very low sample rate. What is the likely problem?

A The volume levels become too fine to store

B Detail of the wave is missed between samples

4. A sound is recorded with a low sample resolution (few bits per sample). What does the volume sound like?

A Coarse, with only a few volume levels to choose from

B Smooth, with many different volume levels

5. Two recordings of the same song are made. Recording A uses 16 bits per sample and recording B uses 8 bits per sample. Both use the same sample rate. Which file is larger?

A Recording B, because it has less accurate samples

B Recording A, because each sample uses more bits

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1sample_rate = 8000		ARaising the sample resolution means more bits for every sample, so the recording is more accurate and the file gets larger, not the same size.
2sample_resolution = 4		BA low sample resolution gives only a few volume levels, so the sound is coarse and less accurate. The file is smaller.
3Two recordings of the same sound: the one with the higher sample rate is more accurate but has the larger file		CA low sample rate takes few samples per second, so it misses detail of the wave. The recording is less accurate but the file is small.
4Lowering the sample resolution gives coarser volume levels and makes the file smaller		DLowering the sample rate means fewer samples are stored, so the file gets smaller, not bigger. Accuracy also drops.
5sample_rate: 44100 -> 8000 # file gets bigger		Eresolution: 16 -> 4, accuracy goes down, file size goes down
6resolution: 16 -> 24 # same file size		FA: rate = 8000, B: rate = 44100 -> B is more accurate, size(B) > size(A)

Definitions

higher sample rate or resolution

Fill in the Blanks

Complete each line of code by filling in the missing parts.

IF newRate _ oldRate THEN accuracy ← "higher" fileSize ← "larger"

resolution ← 4 IF __________ < 8 THEN volumeLevels ← "coarse"

rate ← 44100 IF rate > 8000 THEN ______ "Bigger file, better accuracy"

rate ← 1000 IF rate < 8000 ____ OUTPUT "Misses detail of the wave"

resolution ← 8 resolution _ resolution + 8 OUTPUT "More levels, larger file"

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A rate1 ← 44100

B rate2 ← 8000

C IF rate1 < rate2 THEN

D OUTPUT "File 1 is bigger"

Question 2

A sampleRate ← 8000

B OUTPUT "Captures all detail"

C OUTPUT "Small file"

Question 3

A resolution ← 24

B OUTPUT "Coarse volume levels"

C OUTPUT "Small file"

Question 4

A resA ← 16

B resB ← 8

C IF resA > resB THEN

D OUTPUT "A is smaller file"

Question 5

A sampleRate ← 22050

B sampleRate ← sampleRate / 2

C OUTPUT "Better, bigger file"

Answer Key

Effect of sample rate and resolution on accuracy and file size

Section A: Quick Questions

A — It gets larger because more samples are stored

A — A recording with a high sample rate

B — Detail of the wave is missed between samples

A — Coarse, with only a few volume levels to choose from

B — Recording A, because each sample uses more bits

Section B: Match the Pairs

sample_rate = 8000 → A low sample rate takes few samples per second, so it misses detail of the wave. The recording is less accurate but the file is small.

sample_resolution = 4 → A low sample resolution gives only a few volume levels, so the sound is coarse and less accurate. The file is smaller.

Two recordings of the same sound: the one with the higher sample rate is more accurate but has the larger file → A: rate = 8000, B: rate = 44100 -> B is more accurate, size(B) > size(A)

Lowering the sample resolution gives coarser volume levels and makes the file smaller → resolution: 16 -> 4, accuracy goes down, file size goes down

sample_rate: 44100 -> 8000 # file gets bigger → Lowering the sample rate means fewer samples are stored, so the file gets smaller, not bigger. Accuracy also drops.

resolution: 16 -> 24 # same file size → Raising the sample resolution means more bits for every sample, so the recording is more accurate and the file gets larger, not the same size.

Section C: Definitions

higher sample rate or resolution — Raising the sample rate or sample resolution records the sound more accurately, but it also makes the audio file bigger. Lowering either does the opposite: less accurate, smaller file.

Section D: Fill in the Blanks

IF newRate > oldRate THEN
  accuracy ← "higher"
  fileSize ← "larger"

resolution ← 4
IF resolution < 8 THEN
  volumeLevels ← "coarse"

rate ← 44100
IF rate > 8000 THEN
  OUTPUT "Bigger file, better accuracy"

rate ← 1000
IF rate < 8000 THEN
  OUTPUT "Misses detail of the wave"

resolution ← 8
resolution ← resolution + 8
OUTPUT "More levels, larger file"

Section E: Spot the Error

C — 44100 is greater than 8000, so recording 1 has the higher sample rate and the bigger file. The condition should be rate1 > rate2.

B — A low sample rate takes few samples, so it misses detail of the sound wave. The line should say it misses wave detail.

A — The output describes low resolution (coarse levels, small file). A high value like 24 bits would give fine levels and a larger file, so the value should be low, such as 4.

D — Recording A has the higher sample resolution, so it is more accurate and its file is larger, not smaller.

B — The output says the recording gets better and the file bigger, which needs a higher rate. The rate should be multiplied (increased), not divided.