NRC VS STC - What's The Difference? - www.AcousticFields.com

Summary

In this video, Dennis Foley from Acoustic Fields explains the difference between NRC (Noise Reduction Coefficient) and STC (Sound Transmission Class). He clarifies that NRC measures how much sound a product absorbs, with values ranging from 0 to 1, while STC represents materials that block sound from passing through structures. Foley emphasizes the importance of choosing the right materials for specific sound issues, such as voice and music, and the need to measure sound frequencies and amplitudes accurately before construction. He also highlights the services offered by Acoustic Fields, including noise and treatment design, as well as a dedicated forum for expert advice.

Takeaways

• 😀 NRC (Noise Reduction Coefficient) is a rating of how much sound a material absorbs, with values ranging from 0 (no absorption) to 1 (100% absorption).
• 😀 STC (Sound Transmission Class) is a class of materials that block sound transmission through structures, measured in decibels (dB).
• 😀 NRC measures absorption within a room, helping control reverberation and sound clarity in spaces like studios or theaters.
• 😀 STC focuses on preventing sound leakage between rooms, making it essential for soundproofing applications.
• 😀 Materials with high NRC values are ideal for absorbing sound in environments requiring acoustic clarity, like recording studios.
• 😀 Materials with high STC values are designed to prevent sound from passing through barriers, which is crucial for soundproofing walls, floors, and ceilings.
• 😀 It’s essential to choose the right materials for both NRC and STC to create an effective acoustic environment tailored to specific needs.
• 😀 Music and voice require specific absorption characteristics that standard materials with general NRC ratings may not meet, so careful selection is necessary.
• 😀 Measuring sound frequencies and amplitudes before choosing materials helps ensure the right NRC and STC ratings are selected for the task.
• 😀 Always measure sound levels first—this allows for the correct choice of materials with the proper NRC and STC to meet the acoustic requirements.
• 😀 Incorrect material selection can lead to ineffective acoustic treatments, sometimes requiring costly structural changes, so getting it right from the start is crucial.

Q & A

What is NRC?

NRC stands for Noise Reduction Coefficient. It is a rating system that measures how much sound a product absorbs, with values ranging from 0 (no absorption) to 1 (100% absorption).

What does an NRC rating tell us about a product?

An NRC rating tells us the effectiveness of a product in absorbing sound. A higher value indicates better sound absorption, while a lower value means less absorption.

What is the primary difference between NRC and STC?

NRC is a rating of sound absorption, while STC (Sound Transmission Class) refers to the effectiveness of materials in blocking sound from passing through structures. NRC is used for sound-absorbing products, and STC is used for soundproofing barriers.

How does STC measure soundproofing effectiveness?

STC measures the effectiveness of a material in blocking sound from one side to another. It is quantified in decibels (dB SPL), with higher STC values indicating better sound isolation.

What types of materials are rated by STC?

STC applies to materials used for soundproofing barriers, such as walls, windows, and doors, to prevent sound from passing through from one area to another.

Why is it important to consider both NRC and STC when designing for sound control?

It's important to consider both NRC and STC because NRC helps with controlling the sound within a room (absorbing sound), while STC is necessary for controlling the sound that passes through walls and structures (blocking sound).

Can regular building insulation be used to absorb sound for music and voice environments?

No, regular building insulation may not be suitable for absorbing sound in music and voice environments. These require materials with specific NRC ratings tailored for those frequencies and amplitudes.

What is the importance of measuring sound before choosing materials for a project?

Measuring sound is crucial because it helps determine the right materials with the appropriate NRC and STC ratings to address the specific needs of sound absorption or transmission control. Without proper measurement, the chosen materials might not be effective.

Why should soundproofing projects avoid building structures without proper measurement?

Building a structure without proper measurement can lead to ineffective soundproofing, potentially requiring costly demolition and rebuilding. Proper measurement ensures the use of materials that meet the necessary sound control standards.

How does the seven-day noise time study help in selecting materials for soundproofing?

The seven-day noise time study helps by analyzing the frequency and amplitude of the noise in the environment. This data is used to select materials with the correct STC and NRC ratings to effectively manage the sound.