Composite Wall Transmission Loss Calculator

Should you upgrade the largest wall area first?

A small door, window or open gap can dominate the sound energy transmitted through an otherwise effective partition.
This calculator combines non-overlapping, parallel areas using transmission loss measured in matching frequency bands.
It helps identify which parts deserve further investigation before committing to a soundproofing proposal.
The results describe an input model and do not guarantee installed performance.

Current and proposed scenarios use the same total comparison area.
You can change a component TL, or change a window or door area while reallocating the remaining area to the wall.
An expensive wall upgrade may make little difference if an unchanged weak path still dominates transmission.
This is a global physical calculation using m², Hz and dB; the optional quote is recorded in KRW without applying Korean tax or building rules.

Features and the order to read results

Read the composite TL first, then the dominant parts and the proposed ranking.
Improving a door may leave a window as the next dominant path.
The optional quote stays with the report but does not affect the acoustic calculation or create an automatic purchasing recommendation.

Prepare areas and laboratory reports

• Total area includes doors, windows and openings.
  Enter net wall area after removing those areas to prevent double counting.
  
• Use TL at the same center frequency and bandwidth for every part.
  Do not mix octave and one-third-octave measurements, and check that test methods and installation conditions are comparable.
  
• Record the report, assembly, thickness, frame, mounting, open/closed state and test date in the notes.
  A glass-only measurement may not represent a complete framed window.
  
• A blank area or TL means unknown.
  Use 0 m² for a part that is absent and numeric 0 dB for an actual zero transmission-loss input.
  

Area-weighted transmission loss formula

Sᵢ is area in square meters, TLᵢ is transmission loss for that band and τᵢ is the transmitted fraction of incident energy.
Convert decibels into linear transmission coefficients before multiplying by area and summing.
Convert the area-weighted total back into decibels at the end.
Adding TL values or taking their arithmetic area-weighted average does not perform this calculation.

The model assumes equal incident sound intensity over parallel areas.
If all parts have the same TL, the composite result has that TL regardless of the area split.
Splitting one identical part into several rows also leaves the result unchanged.
Layers stacked on top of one another require complete assembly data and cannot be treated as parallel areas.
Intermediate values are not rounded; displayed TL and contribution percentages use two decimal places.

Step-by-step use

1. Measure one comparison face and separate its wall, door, window and open-gap areas.
   Do not add overlapping areas or unrelated ceiling surfaces.
   
2. Select three report bands and the matching bandwidth.
   Initial centers of 125, 500 and 2,000 Hz are editable conveniences, not product assumptions or confirmation of a standard band set.
   
3. Enter current and proposed areas, types and TL values.
   Both area totals must equal the same full comparison area, including unchanged components.
   
4. Confirm that the test conditions are comparable.
   Missing bands remain pending even after this confirmation.
   
5. Review dominant paths and ΔTL together, record the quote scope and save the TXT file for an acoustic specialist.
   

The interface supports up to 8 parts and three distinct integer frequencies from 20–20,000 Hz.
Area is limited to 1,000,000 m², TL to 0–120 dB and the optional quote to 1 trillion KRW.
These limits bound the software and are not engineering recommendations.
Decimal and comma input is supported, and an empty numeric field is not silently treated as zero.

Worked example: 9 m² wall and 1 m² door

The example button loads wall TL [40, 50, 55] dB, current door TL [15, 20, 25] dB and proposed door TL [25, 30, 35] dB at 125, 500 and 2,000 Hz.
Its 1,000,000 KRW quote is fictional too.
These numbers are neither certified product performance nor market prices; reset before entering actual project data.
Alternatively, retain door TL 20 dB but reduce its area to 0.5 m² and increase the wall to 9.5 m²: composite TL at 500 Hz becomes approximately 32.93 dB.

Open gaps and area changes

An opening is idealized as fully transmitting, with τ=1 and TL=0 dB.
For a 10 m² partition, a 9.9 m² wall at 50 dB plus a 0.1 m² opening gives approximately 20.00 dB composite TL.
Even an ideal blocking wall would leave a limit near 20 dB when 1% of the area is open.
Real small-gap geometry, depth, resonance and diffraction are not resolved by this simplified model.

Practical scenarios and quote comparison

• Compare a smaller window area with a same-size replacement offering different tested TL.
  Daylight, ventilation, appearance and installation feasibility require separate review.
  
• If a door upgrade barely changes the composite result, inspect other contributions.
  A remaining dominant opening is a reason to investigate site leakage and the supporting data.
  
• For low-frequency complaints, do not judge a proposal only by a higher-frequency improvement.
  Match the problematic frequency range to the test-report bands with professional help.
  

Record whether the proposed quote includes removal, frames, finishing, transport and additional charges.
Equal totals may cover different work.
The tool does not estimate market prices or taxes, and an omitted quote does not prevent an otherwise complete acoustic calculation.
To compare two proposals, enter them in turn and save separate reports using identical current conditions.

Frequently asked questions