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Explain sound and its medium

About 10 minutes · 3 reading + 7 practice and checks
Time includes reading, practice, and questions. Extra videos or further study are optional.
See this course’s project requirements

A wave model comparison with period/frequency calculations, reflection and refraction diagrams and an explanation of a fictional communication failure.

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What to include

  • Separate traveling patterns from local material motion.
  • Calculate period and frequency from complete cycles.
  • Compare amplitude under stated fixed conditions.
  • Compute sound wavelength and explain medium requirements.
  • Draw reflection and qualitative refraction using normals.
  • Explain the chamber signal failure and complete all changed cases.

Review and revise

Use these criteria to check your work and choose what to improve.

  • Method: applies the course-specific rules to the supplied cases with visible intermediate work.
  • Accuracy: results agree with the stated facts, units, boundaries and independent checks.
  • Reasoning: explains why the result follows and identifies a limitation or unresolved question.
  • Transfer: completes changed cases and revises the final project when a relevant assumption changes.
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Before you begin

The idea in everyday life

Paper sound model: speed 340 m/s in the stated air conditions; frequency 170 Hz. No sound is played and no hearing exposure task is required.

The idea

Sound is a mechanical disturbance that requires material such as air, water or a solid. For a supplied uniform medium, wave speed v, frequency f and wavelength λ relate by v=fλ. Changing the medium can change speed; it does not make sound travel through a vacuum. Frequency remains a source property across a stationary boundary in this simple model.

Follow along

Explain sound and its medium — worked practice

Sound is a mechanical disturbance that requires material such as air, water or a solid. For a supplied uniform medium, wave speed v, frequency f and wavelength λ relate by v=fλ. Changing the medium can change speed; it does not make sound travel through a vacuum. Frequency remains a source property across a stationary boundary in this simple model.

Paper sound model: speed 340 m/s in the stated air conditions; frequency 170 Hz. No sound is played and no hearing exposure task is required.

  1. 1. 1. Relate

    Rearrange v=fλ to λ=v/f.

    You should see: Wavelength is speed divided by frequency.

  2. 2. 2. Calculate

    Use the supplied values.

    You should see: λ=340/170=2 m.

  3. 3. 3. Medium

    Identify what carries this sound disturbance.

    You should see: The stated air supplies the mechanical medium.

  4. 4. 4. Limit

    Explain why the same model cannot describe audible propagation through empty space.

    You should see: Without a material medium, this sound wave does not propagate through the vacuum.

Now change one thing

Keep speed 340 m/s and change frequency to 85 Hz. Enter wavelength in meters.

Your work

What to finish

A wavelength calculation with medium and fixed-speed assumptions.

Common mistake

Watch for this

Fromλ=v/f, halving the denominator doubles wavelength under the fixed-speed condition. The wave remains sound in the stated medium.

How can I tell I understand it?

Recalculate a changed frequency while keeping the supplied medium speed fixed.

Try 3 questions

Quick knowledge check

Answer all 3 questions. Get at least 2 right and the lesson completes automatically.

Not yet passed

You’ll get an explanation for each answer. Signed in? Your results save to your account.

1What is the supplied wavelength?
2What permits sound propagation in this case?
3At fixed 340 m/s speed, what happens when frequency halves?
0 of 3 answeredApply the lesson to a short question, then review the explanation.
4
Finish this lesson

Pass the check. We’ll save the progress.

Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.

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Sources and further reading

Explore the references behind this lesson.

OpenStax: sound speed and wavelength
Source & access notes · checked 2026-10-01

Web open/search showed the official page, its topic heading and relevant concept description. This is a content/source check, not a provider endorsement.

Access: Official page retrieved with the web reader on 2026-10-01; interactive tools and videos were not certified by retrieval.

Reuse: Original fictional teaching cases, calculations, questions and examples; link and short factual paraphrase only. No copied source exercises or illustrations.

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