How To Test Soundproofing: A Step-By-Step Guide To Sound Insulation Testing

If you are looking to soundproof your space effectively, testing is a must. You could wing it and rely solely on your ears to check for success, but for almost all the reasons you would want to soundproof, using your ears is a waste of time and money—especially considering that there are simple, cheap tests nowadays you can do at minimum that can provide a powerful baseline for choosing the correct soundproofing products.

In this article, I’m going to assume you’re a professional or—at least, a prosumer— and want to take soundproofing seriously, and for some soundproofing scenarios, sound insulation testing is a serious, professional business.

Soundproofing is a science that maximizes art and function, so we need to utilize precision in the planning stages before buying any product that offers soundproofing capabilities to achieve desired results.

You can expect to learn the purpose of soundproofing, how it works fundamentally, how to decide on the level of soundproof testing for your specific needs, and finally the types of materials and products you can then purchase and install to achieve your acoustic goals.

Before looking at how to test soundproofing, it’s important to understand the common acoustic ratings:

An STC rating is a measurement used to calculate the effectiveness of soundproofing materials in reducing sound transmission between rooms. In other words, when performing sound insulation testing, the STC rating identifies how many decimals you’re going to block or reduce in a given material.

The higher the STC rating, the more effective the material is at reducing sound transmission.

A NIC rating is a field measurement of the total sound insulation performance between two rooms. Essentially, an NIC is the field test version of an STC. It’s the same test, but STC is more accurate as it’s performed in a lab in controlled conditions.

An NRC rating is the average of how much sound an acoustic product can absorb, or how much reverb and echo can be reduced. Like a sponge absorbs water, an acoustic product absorbs sound and the NRC tells us how much sound those products can soak up.

Put simply: STC and NIC ratings are geared towards either containing the sound or keeping unwanted sounds out, while NRC ratings are for making your room sound better.

There are two ways to test soundproofing in your space: do it yourself or employ a soundproofing professional, also called an acoustician. The latter will always be preferable because of their instruments, skill, and knowledgeable insights but, depending on your goals and budget, an acoustician isn’t entirely necessary.

We live in a wonderful time where the “prosumer” can readily test the acoustics in their space with cheap equipment and software to determine a relatively precise reading from which to select the right soundproofing materials. In the most basic version, there is free software that can be found as a phone application that uses the phone’s microphone.

While you can get decent results with your phone, the one aspect lacking is the microphone. It’s simply not capable of getting precise readings. To solve this, there are numerous, relatively inexpensive reference microphones you can purchase that will dramatically improve your results while utilizing the same software.

You want to perform your test by selecting a frequency in the software at a set decibel level. In choosing the frequency and decibel level, it’s important to consider the sounds you are soundproofing for because different frequencies are harder to soundproof for than others.

If soundproofing a home studio, for example, consider the types of sounds you’ll be making. (Drums, for example, create more low frequencies and are therefore harder to soundproof than the sounds of voices and acoustic guitars.)

You would then be best served by selecting a lower frequency for your testing. Likewise, if you’re testing for a home theater, the loudest parts of a film—explosions, gunfire, etc —are the sounds that need to be soundproofed for most, so select a frequency that applies.

Often home theaters employ subwoofers to pack that low end punch, so, again, selecting a lower frequency and at the volume you’ll be playing it is key.

The more data you collect, the more precision you can achieve via the DIY method. At minimum, the space needs to be tested and the space in adjoining rooms needs to be tested.

Begin by placing the microphone in the middle of the space with no sound for a baseline reading. Once complete, turn on your sound source and test it playing your chosen frequency. Finally, place the reference mic in an adjoining room, turn on the sound source, and run the test. You should then perform these tests again so you have two sets of data for precise results.

To be even more precise, you can test the space to be soundproofed with multiple placements of the mic. I suggest testing once with the mic near the soundsource, once with the mic in the middle of the room, and a final time with the mic at the farthest end of the room. Again, do all of these tests at least a second time so you can get a good data set. The more points of data you collect, the more precision you will have to make the right choice for your specific circumstances.

There are numerous references available on the internet that you can analyze with your collected data to determine how your room is currently soundproofed and the materials and methods you need to employ to achieve your final goal. By comparing test results to industry standards and benchmarks, you can get a great idea of what you will need to soundproof the room.

If you’ve exhausted your DIY skills, you can share your results with an acoustical professional who can analyze it for you. This is the best of both worlds, because you saved money by performing the tests yourself, but now you can rely on a professional to take the data and use their knowledge of acoustics and soundproofing products and materials to find exactly what you need.

The most unfortunate circumstance is properly soundproofing walls, ceilings, windows, doors, and floors only to realize you missed the ventilation! Ventilation equipment and systems can absolutely affect soundproofing, and needs to be taken into consideration.

When testing, you will want to run your HVAC systems as part of the test to see how negatively – if at all – it is impacting the situation, so you can include treating that aspect of the room as well.

All kinds! All sound is the same, there are just differences in frequency (pitch) and intensity (loudness). Generally speaking, the lower the frequency and greater the intensity, the more “dense” soundproofing materials need to be in order to be effective.

For example, if your space is often passed by traffic, the rumble of larger vehicles could pose a much bigger problem than the bark of a dog or sound of voices, and will need to be taken into consideration.

Yes, any added material helps block sound, but you want to be careful as furniture in your space might negatively affect the experience you’re trying to create. For example, if a chair is between you and the speakers, it will block sound, but you want to hear that sound! Things like rugs and carpet are excellent soundproofing helpers for home studios and home theaters.

If you’re interested in a professional test with our experts, we offer 3 different levels of service:

Give us a call today and let’s talk about your soundproofing project! There is nothing too big or too small that we can’t handle, and I’ll be able to steer you towards the industry’s best products after testing completes to achieve the exact results you’re looking for!