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What Is STC · Made Simple
STC (Sound Transmission Class) is the standard for measuring how well a building material "blocks sound" under ASTM E413 · a single number, and the higher it is the better the sound insulation.
- · STC 25 — normal conversation is audible (a lightweight wall)
- · STC 30–35 — speech is muffled, words unintelligible (clear 6 mm glass)
- · STC 35–40 — loud speech disappears (Smart Glass Laminated)
- · STC 40–50 — only very loud sounds get through (Smart Glass IGU)
- · STC 50+ — recording studio · specialist sound-absorbing rooms
Why Smart Glass Blocks Sound So Well
The secret is the 5-layer structure of Smart Glass, which absorbs sound naturally — unlike an ordinary single pane of clear glass that "resonates" and lets all the sound through.
- Layer 1 · outer Tempered glass — reflects some of the higher-frequency waves
- Layer 2 · outer EVA Interlayer — a tough bonding film that absorbs sound like rubber, the main sound-insulation layer
- Layer 3 · PDLC Smart Layer — the liquid crystal layer that scatters sound waves
- Layer 4 · inner EVA Interlayer — another layer of sound absorption
- Layer 5 · inner Tempered glass — blocks the final sound waves
Comparison: a single 6 mm pane of clear glass = 1 rigid layer · Smart Glass = 5 alternating rigid-flexible layers = better sound absorption.
STC Comparison · Each Type of Glass
| Glass type | STC | Noise reduction (dB) | What you'd hear |
|---|---|---|---|
| Single clear 6 mm glass | 30–32 | ~25 dB | Traffic, sirens, birdsong clearly audible |
| Laminated 6+6 mm glass (standard) | 34–36 | ~28 dB | Speech muffled, loud sounds still audible |
| InHouse Smart Glass Tempered Laminated | 35–38 | 30–35 dB | Speech disappears · only very loud sounds audible |
| Standard 2-pane IGU (no Laminated) | 32–34 | ~28 dB | Close to Laminated |
| InHouse Smart Glass IGU | 38–42 | 35–42 dB | Almost complete quiet · only low bass audible |
| Smart Glass IGU + Acoustic EVA (Custom) | 44–48 | 40–45 dB | Recording-studio grade |
STC values tested on samples · real results depend on the frame, the seals around the glass, adjacent wall insulation and the direction of the sound.
Real Cases · Smart Glass Sound Insulation on the Job
Case 1 · a meeting room by a street window
A Sathorn office with a meeting room against the street-side glass — passing traffic and sirens broke concentration · switched to Smart Glass Tempered Laminated → traffic noise down ~30 dB · staff feedback: "With the meeting door closed, it feels like being on another floor."
Case 2 · a 5-star hotel · a room beside the BTS
A boutique hotel near the BTS · a Master Suite fitted with Smart Glass IGU → the sky-train noise reduced to a faint bass · STC ~42 · a guest review: "I never knew there was a BTS running right past my room."
Case 3 · a clinic · an exam room
An Ekkamai clinic · an exam room with glass dividing it from the lobby · Smart Glass Laminated cut cross-room speech so patients in the lobby couldn't hear — meeting the HIPAA-style privacy required in medical settings.
Case 4 · a Penthouse condo
A riverfront condo on the 35th floor · a hybrid-working client wanted the quietest possible bedroom · Smart Glass IGU + Acoustic EVA → STC 46 · boat and traffic noise almost entirely gone · switched to opaque only when changing.
Compared with Other Options
| Option | Noise reduction | Has privacy? | Average price |
|---|---|---|---|
| Thick curtain / soundproof curtain | 5–10 dB | Fixed closed | 3,000–8,000 THB/panel |
| Dedicated acoustic film | 3–7 dB | None | 1,500–4,000 THB/sqm |
| Replace with standard Laminated glass | 5–8 dB | None | 5,000–9,000 THB/sqm |
| 2-pane IGU glass (no Smart) | 15–20 dB | None | 9,000–14,000 THB/sqm |
| InHouse Smart Glass Laminated | 30–35 dB | Yes + adjustable | 14,500–22,500 THB/sqm |
| InHouse Smart Glass IGU | 35–42 dB | Yes + adjustable | 19,500–22,500 THB/sqm |
The strength of Smart Glass: you get both sound insulation + on-demand privacy in a single pane of glass · the other options split the functions and require several separate investments.
Which STC Level to Choose
- · STC 35–38 (Laminated) · enough for: office meeting rooms · homes in quiet areas · ordinary bedrooms · condos not on a major road
- · STC 38–44 (IGU) · needed for: rooms beside the BTS · condos on major roads · 5-star hotels · executive rooms wanting complete quiet
- · STC 44+ (IGU + Acoustic EVA) · essential for: recording studios · top-secret meeting rooms · exam rooms needing advanced acoustic privacy
Frame and Seal · the Factor Many Forget
The glass's STC alone isn't enough — the frame and the seals around the glass are where nearly all the sound "leaks through" if done poorly · InHouse installs Smart Glass with:
- · an Acoustic Gasket around the glass edge · absorbing sound into the seal channel
- · Backer Rod + Acoustic Sealant in the gap between the glass and the frame
- · Smart Glass wiring concealed within the frame · no drilled holes that become sound leaks
- · Edge Seal checked on all 4 sides before handover
A finish so seamless it doesn't look like film was installed + sound insulation to spec = the core job of the InHouse team.
Frequently Asked Questions · Smart Glass Sound Insulation
How much better does Smart Glass block sound than standard Laminated glass?
InHouse Smart Glass Tempered Laminated cuts an extra 2-7 dB versus standard clear Laminated glass · because it has thicker PDLC + EVA layers that absorb sound well · and, crucially, you get switchable clear↔opaque privacy in the same pane · with no need to invest in several separate items.
Where are the STC values InHouse quotes tested?
Tested in InHouse R&D's sample room under ASTM E413 · the values are given as a range to reflect real results across installations of different sizes and frames · a model-specific Test Report can be requested during the RFQ stage before ordering.
For a home near an airport, is Smart Glass IGU enough to block aircraft noise?
Aircraft mostly emit low-frequency bass at 50-80 Hz, which ordinary glass blocks poorly · Smart Glass IGU + Acoustic EVA (STC 44+) reduces it substantially, but the walls and ceiling must be considered too · we recommend InHouse send an engineer to assess the site first for the most worthwhile result.
Does swapping the Smart Glass alone make it quiet, or do I need to change the frame too?
It depends on the condition of the existing frame · if it's an aluminum frame that already has an Acoustic Gasket → swapping just the glass is fine · if it's an old wooden frame or the seals have degraded → the seals and Gasket need replacing too · the InHouse team will assess this clearly during the site survey.
Does Smart Glass block the same amount of sound when clear versus opaque?
The same · both states insulate sound equally, because the glass-EVA-PDLC structure doesn't change with the clear/opaque state · what changes is light transmission, not sound.
Where can I see an in-depth Laminated vs IGU comparison?
There is a full Laminated vs IGU comparison article covering structure, price, sound insulation, heat blocking and how to choose per room · read more → Smart Glass Laminated vs IGU · a selection guide
Where can I see the 5-layer structure of Smart Glass in depth?
There is a dedicated article explaining the 5-layer Tempered Laminated PDLC structure with illustrations and the engineering reasoning · read more → Smart Glass Tempered Laminated · the 5-layer structure
Is Smart Glass sound insulation worth it for operating rooms/clinics?
Yes, because Smart Glass Laminated cuts cross-room speech to a HIPAA-style privacy standard · with instant switchable clear↔opaque privacy · very well suited to medical settings · read the full hospital and clinic use case → Smart Film for hospitals and clinics
How noisy is your home/office?
Send the InHouse team a dB Meter App reading taken day and night + your room plan — we'll advise whether Laminated, IGU or IGU + Acoustic EVA fits your budget. Free · no charge.
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