Absorption vs Soundproofing in Japan: Choose Right

Conclusion First: Which Do You Need for Your Situation?

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Three simple decision criteria: If noise comes from outside or goes outside → soundproofing materials. If you’re concerned about echo, muffled sound, or work noise → sound absorption materials. In most cases, a combination is needed. For those starting from zero, the correct order is “soundproofing → sound absorption.” For those with existing soundproofing that’s unsatisfactory, re-evaluate whether you’re addressing “reflection” or “transmission.”

Sound Absorption vs Soundproofing Materials (Abstract → Concrete)

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Abstract Understanding: Role Differences

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Sound Absorption Materials: Weaken sound energy

• Sound waves enter fine pores in the material, creating friction with air that converts to heat
• Reduces indoor reverberation and eliminates sound muffling

Soundproofing Materials: Block sound energy

• Material mass blocks sound waves, preventing them from passing through
• Prevents external sound from entering and internal sound from leaking out

Concrete Material Examples

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Representative Sound Absorption Materials

• Glass wool: ¥2,000-5,000/㎡ (approx. $13-33/㎡), 90%+ absorption rate, best cost-performance
• Urethane sponge: ¥5,000-10,000/㎡ (approx. $33-67/㎡), easy installation, DIY-friendly
• Fabric-wrapped absorption panels: ¥8,000-20,000/㎡ (approx. $53-133/㎡), good appearance, high interior value
• Tencel absorption material: ¥10,000-15,000/㎡ (approx. $67-100/㎡), excellent low-frequency absorption, eco-friendly

Representative Soundproofing Materials

• Gypsum board: ¥2,000-3,000/㎡ (approx. $13-20/㎡), Dr-15 level, basic soundproofing material
• Soundproof gypsum board: ¥4,000-6,000/㎡ (approx. $27-40/㎡), Dr-25 level, 1.5x heavier
• Damping material: ¥3,000-5,000/㎡ (approx. $20-33/㎡), suppresses vibration, supports Dr-35+
• Lead sheet: ¥15,000-30,000/㎡ (approx. $100-200/㎡), Dr-35+, highest class soundproofing
• Composite soundproofing material (soundproof mat): ¥8,000-15,000/㎡ (approx. $53-100/㎡), Dr-30-40, DIY-friendly

NG Examples: Wrong Usage

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NG Example 1: Sound absorption alone cannot stop sound leakage

• Even if you install absorption panels on walls, sound won’t stop leaking to adjacent rooms
• Absorption materials only “reduce reverberation” and don’t have the effect of “preventing sound passage”

NG Example 2: Soundproofing alone worsens indoor reverberation

• Using soundproofing sheets but the room still echoes and is hard to talk in
• Soundproofing materials only “block sound” and don’t have the effect of “eliminating sound”

Correct Understanding

• Sound absorption materials: Counter indoor reverberation and muffling
• Soundproofing materials: Counter sound exchange with outside
• In most cases, a combination of both is needed

Priority Judgments for “Zero Soundproofing” Users

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For those starting soundproofing measures, it’s important to avoid mistakes in direction at minimum cost.

Step 1: Check Which Direction Sound is Moving

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Understanding Sound Movement Direction

Concrete Confirmation Methods

• Telework voice leaking toward stairs → Soundproofing materials
• Concerned about streaming environment noise → Sound absorption materials
• Children’s footsteps and daily noise countermeasures → Soundproofing materials (floor/walls) + Sound absorption materials (indoor reverberation)

Step 2: Basic Leak Prevention (Weak Points: Walls, Doors, Windows)

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Priority Order of Weak Points

1. Door gaps: Most prone to sound leakage

   • Soundproof with gap tape (¥500-1,000 / approx. $3-7)
   • Block gap under door (¥1,000-2,000 / approx. $7-13)

2. Windows: Glass easily transmits sound

   • Install inner window (¥30,000-50,000/window / approx. $200-333/window)
   • Simple countermeasure with soundproof curtains (¥5,000-10,000 / approx. $33-67)

3. Walls: Soundproofing varies by structure

   • Lightweight steel frame: Low soundproofing
   • Concrete construction: High soundproofing

4. Ceiling/Floor: Sound leakage to upper/lower floors

   • Soundproof mat on floor (¥3,000-5,000/㎡ / approx. $20-33/㎡)
   • Sound absorption material on ceiling (¥2,000-5,000/㎡ / approx. $13-33/㎡)

Step 3: Minimum Soundproofing → Then Sound Absorption (Correct Order)

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Correct Installation Order

STEP1: Prevent sound exchange with soundproofing materials
  ↓
STEP2: Reduce indoor reverberation with sound absorption materials

Reason

• If you don’t install soundproofing first, sound absorption alone won’t stop leakage
• Soundproofing alone causes indoor reverberation, so add sound absorption afterward

Expected Effects

Common Complaints and Causes for “Existing Soundproofing” Users

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If you already have soundproofing measures but don’t feel the effects, let’s organize the causes.

Typical Examples and Causes

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Typical Example 1: Installed absorption materials on walls but noise from neighbors hasn’t decreased

Cause

• Absorption materials only reduce “reflection” and cannot prevent “transmission”
• Sound from adjacent rooms is “transmission,” so soundproofing materials are needed

Improvement Plan

• Keep existing absorption materials
• Add soundproofing sheets to walls (¥3,000-5,000/㎡ / approx. $20-33/㎡)
• Or install inner windows for double structure

Typical Example 2: Used soundproofing sheets but room echoes and is hard to talk in

Cause

• Soundproofing materials only prevent “transmission” and cannot reduce “reflection”
• Indoor sound reflects off walls and echoes

Improvement Plan

• Keep existing soundproofing sheets
• Add absorption panels to walls (¥2,000-5,000/㎡ / approx. $13-33/㎡)
• Or install sound absorption material on ceiling

Typical Example 3: Door gaps are the only leak point

Cause

• Addressed walls and windows but overlooked door gaps
• Sound leaking through gaps halves the effectiveness of other countermeasures

Improvement Plan

• Door gap tape (¥500-1,000 / approx. $3-7)
• Block gap under door (¥1,000-2,000 / approx. $7-13)
• Cost-effective “weak point focus” method

Cause Organization: Which Are You Not Addressing - “Reflection” or “Transmission”?

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Difference Between “Reflection” and “Transmission”

Common Mistakes

• Sound absorption materials don’t work for “leakage countermeasures”
• Soundproofing materials tend to negatively affect “how the room sounds”

Improvement Points

• Re-evaluate the role of existing soundproofing materials
• Determine which is missing: sound absorption or soundproofing
• Choose cost-effective “weak point focus” methods

3-Minute Quick Check: Which Are You?

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Answer the following check items to determine necessary countermeasures.

Check Items

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① Where does sound come from and where does it leak?

• Sound coming from outside (car noise, voices from adjacent rooms, etc.)
• Your voice or sound leaking outside (telework, streaming, instruments, etc.)
• Sound reverberating indoors (voices muffled, work noise echoing)
• Sound muffled indoors (hard to hear, too little reverberation)

② When talking indoors, is it “echoing or dead”?

• Echoing (voices reverberate and hard to hear)
• Dead (hard to hear sound, too little reverberation)
• Normal (no particular problem)

③ Is the volume large or small?

• Large (instruments, loud voices, speakers, etc.)
• Small (voices, keyboard sounds, etc.)
• Medium (TV, games, etc.)

④ Do problems occur at night/early morning?

• Particularly concerned at night/early morning
• Concerned regardless of time
• No particular problem

Decision Format

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A: Intrusion from walls/windows → Soundproofing materials

• Sound coming from outside
• Your voice or sound leaking outside
• Large volume
• Particularly concerned at night/early morning

Recommended Countermeasures

• Door gap countermeasure (¥500-1,000 / approx. $3-7)
• Install inner window (¥30,000-50,000/window / approx. $200-333/window)
• Soundproofing sheets on walls (¥3,000-5,000/㎡ / approx. $20-33/㎡)

B: Indoor reflection/muffling → Sound absorption materials

• Sound reverberating indoors
• Sound muffled indoors
• Small volume
• Concerned regardless of time

Recommended Countermeasures

• Absorption panels on walls (¥2,000-5,000/㎡ / approx. $13-33/㎡)
• Sound absorption material on ceiling (¥2,000-5,000/㎡ / approx. $13-33/㎡)
• Glass wool + non-woven fabric (¥2,500-3,500/㎡ / approx. $17-23/㎡)

C: Instruments/Streaming → Both + Weak point countermeasures

• Sound coming from outside + reverberating indoors
• Large volume + concerned about indoor reverberation
• Multiple problems simultaneously

Recommended Countermeasures

• Prevent sound exchange with soundproofing materials
• Reduce indoor reverberation with sound absorption materials
• Focus countermeasures on weak points (doors, windows, gaps)

Specific “Correct Patterns” by Use Case

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We introduce optimal countermeasure patterns for each part.

Walls

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Pattern 1: Leaking outside → Soundproofing materials → Finish with thin absorption panels

[Indoor side]
  ↓
[Absorption panel 30mm] (for finish)
  ↓
[Soundproofing sheet 3mm]
  ↓
[Existing wall]
  ↓
[Outdoor side]

Material Examples

• Soundproofing sheet: ¥3,000-5,000/㎡ (approx. $20-33/㎡)
• Absorption panel: ¥2,000-5,000/㎡ (approx. $13-33/㎡)
• Total: ¥5,000-10,000/㎡ (approx. $33-67/㎡)

Effects

• 70% reduction in sound leakage
• Also reduces indoor reverberation

Pattern 2: Indoor reverberation → Absorption panels alone OK

[Indoor side]
  ↓
[Absorption panel 50mm]
  ↓
[Existing wall]

Material Examples

• Glass wool 50mm + non-woven fabric: ¥2,500-3,500/㎡ (approx. $17-23/㎡)
• Fabric-wrapped absorption panel: ¥8,000-20,000/㎡ (approx. $53-133/㎡)

Effects

• 80% reduction in reverberation
• Eliminates sound muffling

Windows

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Priority is soundproofing (inner windows/soundproof curtains)

Pattern 1: Install inner window (comprehensive)

[Existing window]
  ↓
[Inner window (double structure)]

Material Examples

• Inner window: ¥30,000-50,000/window (approx. $200-333/window)
• Soundproofing effect: Dr-25 level

Effects

• 70% reduction in external sound intrusion
• 70% reduction in internal sound leakage

Pattern 2: Soundproof curtains (simple)

[Existing window]
  ↓
[Soundproof curtains]

Material Examples

• Soundproof curtains: ¥5,000-10,000/window (approx. $33-67/window)
• Soundproofing effect: Dr-10 level (limited)

Effects

• 30% reduction in external sound intrusion
• Medium cost-performance

For reverberation, add sound absorption as needed

• If concerned about reverberation from windows
• Install sound absorption material inside curtains (¥2,000-5,000/㎡ / approx. $13-33/㎡)

Doors

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Gap treatment (soundproofing) + minimal sound absorption to adjust voice reverberation

Pattern 1: Gap countermeasure (soundproofing)

[Door gap]
  ↓
[Gap tape]
  ↓
[Block gap under door]

Material Examples

• Gap tape: ¥500-1,000 (approx. $3-7)
• Gap under door countermeasure: ¥1,000-2,000 (approx. $7-13)
• Total: ¥1,500-3,000 (approx. $10-20)

Effects

• 50% reduction in sound leakage

Pattern 2: Add sound absorption to door (reverberation countermeasure)

[Inside of door]
  ↓
[Absorption panel 30mm]

Material Examples

• Absorption panel: ¥2,000-5,000/piece (approx. $13-33/piece)

Effects

• 30% reduction in indoor reverberation

Ceiling/Floor

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“Heavy soundproofing” is essential for lower floors

Pattern 1: Soundproof mat on floor (countermeasure for sound leakage to lower floor)

[Floor]
  ↓
[Soundproof mat 20mm]
  ↓
[Existing floor material]

Material Examples

• Soundproof mat: ¥3,000-5,000/㎡ (approx. $20-33/㎡)
• Soundproofing effect: Dr-20 level

Effects

• 50% reduction in sound leakage to lower floor

Light sound absorption is sufficient for reverberation countermeasures

Pattern 2: Sound absorption material on ceiling (reverberation countermeasure)

[Ceiling]
  ↓
[Absorption panel 50mm]

Material Examples

• Glass wool 50mm + non-woven fabric: ¥2,500-3,500/㎡ (approx. $17-23/㎡)
• Fabric-wrapped absorption panel: ¥8,000-20,000/㎡ (approx. $53-133/㎡)

Effects

• 70% reduction in ceiling reverberation

Budget-Based: Most Effective Combinations at Minimum Cost

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We introduce the most effective combinations according to budget.

Around ¥3,000: Door gap countermeasure (soundproofing) + small absorption panels for reverberation

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Combination

• Door gap tape: ¥500-1,000 (approx. $3-7)
• Gap under door countermeasure: ¥1,000-2,000 (approx. $7-13)
• Small absorption panels (1-2 pieces): ¥1,500-2,000 (approx. $10-13)
• Total: ¥3,000-5,000 (approx. $20-33)

Effects

• 50% reduction in sound leakage
• 30% reduction in indoor reverberation

Suitable Uses

• Telework voice leakage countermeasure
• Streaming environment noise reduction
• Light instrument practice

Around ¥10,000: Sound absorption on walls + soundproofing sheets on weak points

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Combination

• Glass wool 50mm + non-woven fabric (2㎡): ¥5,000-7,000 (approx. $33-47/2㎡)
• Soundproofing sheets (door/window areas): ¥3,000-5,000 (approx. $20-33)
• Installation tools: ¥2,000 (approx. $13)
• Total: ¥10,000-14,000 (approx. $67-93)

Effects

• Reverberation improvement: 80% reduction
• Leakage reduction: 40% reduction
• Well-balanced countermeasure

Suitable Uses

• Streaming environment improvement
• Basic music production countermeasures
• Comprehensive telework countermeasures

Around ¥30,000: Sound absorption on ceiling/walls + soundproof windows (top priority)

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Combination (walls/ceiling only - around ¥30,000)

• Glass wool 50mm + non-woven fabric (10㎡): ¥25,000-35,000 (approx. $167-233)
• Soundproofing sheets (weak points): ¥5,000 (approx. $33)
• Total: ¥30,000-40,000 (approx. $200-267)

Effects

• Reverberation improvement: 85% reduction
• Leakage reduction: 50% reduction
• “Optimal solution zone” for rental properties

Suitable Uses

• Comprehensive streaming environment
• Basic music production environment
• Complete telework countermeasures

Finally: Sound Absorption and Soundproofing Are Not Opposites but “Role Division”

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Summary: Correct Understanding and Practice Flow

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① First, understand “sound pathways”

• Sound coming from outside → Soundproofing materials
• Sound going outside → Soundproofing materials
• Sound reverberating indoors → Sound absorption materials
• Sound muffled indoors → Sound absorption materials

② Next, judge “reverberation or leakage”

• Concerned about reverberation → Sound absorption materials
• Concerned about leakage → Soundproofing materials
• Concerned about both → Combination

③ Finally, adjust in correct order “soundproofing → sound absorption”

• Prevent sound exchange with soundproofing materials
• Reduce indoor reverberation with sound absorption materials
• Focus countermeasures on weak points (doors, windows, gaps)

Beginners Often Make Mistakes with Sound Absorption Only/Soundproofing Only

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Common Mistakes

• Installing only sound absorption materials, sound leakage doesn’t stop
• Using only soundproofing sheets, room echoes
• Overlooking door gaps, halving effectiveness of other countermeasures

Correct Understanding

• Sound absorption and soundproofing are not “opposites” but “role division”
• Combine both according to purpose
• Focusing countermeasures on weak points maximizes effectiveness while controlling costs

Practice Tips

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1. Clarify purpose → Which is priority: reverberation or leakage?
2. Set budget → Choose from ¥3,000-40,000 range (approx. $20-267)
3. Identify weak points → Focus on doors, windows, gaps
4. Install in stages → First soundproofing, then sound absorption
5. Confirm effects → After installation, add countermeasures if problems remain

By understanding the difference between sound absorption and soundproofing and taking countermeasures in the correct order, you can achieve maximum effectiveness at minimum cost.

Create the optimal soundproofing environment with correct knowledge!