How Interior Doors Reduce Sound Transmission

interior-doors-reduce-sound

Your dishwasher shouldn’t be quieter. Better-performing interior doors reduce sound transmission!

How often are you irritated because you can hear your dishwasher or washing machine in the next room? Or maybe you’d like not to hear your teenager’s loud music? What if many of the sounds you’d like to block could be significantly minimized just by upgrading your interior doors? Well, that’s certainly a possibility.

In this post, you’ll learn how interior doors reduce sound transmission.

How sound travels

When sound comes into contact with a barrier like an interior door, some of the energy from the vibrations transfers to the door. The resulting vibrations in the door then set the air in motion, creating sound on the other side of the door. The mass and stiffness of the barrier impact how much sound will transfer.

Thus, the inside of your interior door is critical when considering noise reduction.

Why your interior doors matter

Busy homes or active areas create a lot of noise. However, you’d probably like to keep that noise confined to its space. Upgrading your interior doors is a budget-friendly, easy solution. You’ll want to determine the Sound Transmission Class (STC) and/or the OITC (Outdoor-Indoor Transmission Class). You can read more about STC and OITC in our blog.

Once you’ve determined what your level of sound reduction is, then you can review all the doors that meet those requirements. We offer ProCore® solid cores for all molded doors as an upgrade. This can reduce the transmission of sound by up to 50 percent compared to a hollow core door.

Our TRIA™ interior doors are carved from composite wood and have a solid core. The TRIA collection doors have the highest STC ratings of all our interior doors.

Where better interior doors will benefit you the most

Where to install higher-quality interior doors depends on the layout of your space as well as what occurs in it. We’ve discussed the annoying sounds of a dishwasher and washing machine. If your home has its own laundry area, install a solid core door here to reduce the myriad of sounds. Kitchens are typically open spaces now, so it might be harder to ignore the dishwasher.

They also make sense in bathrooms or bedrooms. Again, these are noisy areas, so a great solid door in a child’s bedroom will hopefully keep him or her asleep. For bathrooms, eliminate noise related to plumbing and the blow dryer.

By reducing the transmission of sound throughout your home, you can create a better experience for each of your spaces. And interior door upgrades are certainly not a blow-the-budget kind of upgrade. It’s worth checking out some better doors if the noise in your space is impacting your quality of life.

We invite you to review all our interior doors. Better interior doors reduce sound transmission, providing you a more serene environment. Just another way that JELD-WEN is here to make your possibilities come true.

Sound Transmission Ratings: STC Versus OITC

Sound-Transmission-Ratings

When discussing sound transmission ratings for windows and doors, there are two different scales. In this post, we’ll look at Sound Transmission Class (STC) and Outdoor-Indoor Transmission Class (OITC) ratings and what they mean.

Sound Transmission Loss (TL)

A door’s ability to reduce noise is called its TL effectiveness. TL is a decibel value, determined by measuring sound pressure levels and certain frequencies. It also accounts for reverberation time (the length of time required for sound to decay 60 decibels from its initial level). The higher the TL, the better the door or window is at reducing noise transmission.

STC

Because TL ratings are based on a range of frequencies, it’s hard to know how accurate they are. STC ratings provide a single value of the acoustic performance of a door. STC is a weighted average of TL values over 16 frequencies. The higher the STC value, the better the performance.

We can divide STCs for interior doors into groupings:

  • STC 40-60: Best (loud sounds or speech heard faintly)
  • STC 25-40: Better (loud speech heard fairly well)
  • STC 20-25: Good (low speech audible)

Sound transmission ratings: The difference between STC and OITC

OITC is much newer than STC, originating in 1990. It also emphasizes the transmission of street sounds (horns, sirens, airplanes) through exterior walls, windows and façade elements. STC doesn’t focus on specific kinds of sounds, only how they transmitted through walls, doors and windows. OITC is not universally adopted, so STC ratings are still more prevalent.

Professionals have been using the STC rating system to measure sound transmission for decades. Originally evaluating transmission through interior walls only, you can use STC to assess almost any type of barriers: exterior walls, interior walls, windows and doors.

Exterior noise tends to be a lower frequency than interior noise (such as voices), so the OITC rating system emphasizes low-frequency sounds in its calculations. Professionals use OITC less frequently than the STC.

How OITC is measured

Like the STC rating System, OITC measures sound intensity loss in decibels. If a 105-decibel above-ground subway only registers as 80 decibels after traveling through a window, the sound experiences a 25-decibel deficit. The ability of a barrier to create a specific decibel deficit varies according to the frequency of the sound passing through it. In general, very high and very low frequency sounds are more difficult to block.

A barrier’s OITC rating is measured using data gathered over an 80 to 4000 hertz frequency range. After data collection, testers calculate the barrier’s OITC rating in accordance with standards laid out by the American Society for Testing and Materials (ASTM). Typically, a barrier’s OITC rating is lower than its STC rating.

What do STC and OITC ratings really mean

Ratings of sound transmission can be subjective. There are benchmarks that provide a standard platform for deciphering acoustic performance. Here are some examples:

2×4 exterior wall

A typical 2×4 wall with insulation in a stick-built home has an STC rating of around 36. Unless the entire structure is engineered for sound control, there is little value to purchasing windows with a higher rating than the wall. If the windows rate higher than the wall, sound enters the structure through the walls. Additionally, if the structure is old and not well-designed, sound-control windows may do little to nothing to improve the situation.

Single-pane windows

Existing single-pane windows often have an STC rating between 18 and 20. Replacing old single-pane units with new acoustic windows will likely have a noticeable effect.

Dual-pane windows

New dual-pane windows with standard glass fall in the STC 25-27 range. In many situations, this can reduce sound by as much as 40 percent when replacing single-pane windows with dual-pane. High-noise environments may require higher ratings.

When building or remodeling a space, it’s important to consider how sound will travel and where the weak spots might be. By looking at STC and OITC ratings, you can choose the windows and doors that best fit your needs.

Learn more about JELD-WEN products’ sound transmission ratings by reviewing our Technical Acoustic Documents.