ISO 23351-1:2020 is a newly introduced standard that evaluates the ability of telephone booths, work pods, and other furniture assemblies to reduce speech levels. Through specified testing methods, it calculates a metric called “Speech Level Reduction”, expressed as D (decibels/dB). This standard is the first of its kind specifically designed for cabins and similar partially enclosed furniture units. Office pods are classified A+, A, B, C, or D based on the level of speech reduction they provide. Office pods in Classes A+, A, and B ensure the highest levels of speech privacy.

1. Use high-density soundproofing materials (e.g., metal, concrete, glass) on primary surfaces to effectively reduce sound wave transmission.

2. Optimize gap sealing using waterproof adhesives, sealing strips, or appropriate sealing materials to ensure minimal noise leakage.

3. In areas where complete soundproofing is unachievable (e.g., ventilation ducts), increase the distance of sound travel and apply sound-absorbing materials (e.g., PET acoustic felt) along the path to dissipate sound energy.

STC (Sound Transmission Class): A method for measuring a material’s ability to block sound, commonly used to test partition materials like walls and screens. A higher STC value indicates better sound-blocking performance. STC is critical for evaluating walls that isolate conversation areas.

NRC (Noise Reduction Coefficient) measures the sound isolation effectiveness between two rooms post-construction. A higher NRC value signifies better sound isolation.

While STC and NRC are similar, they differ in application:

NRC is a field measurement conducted in real-world spaces, whereas STC is a laboratory measurement.

STC does not account for factors like sound absorption in the receiving room, making NIC a more comprehensive metric for evaluating sound isolation between rooms, beyond just the partition itself.

Speech intelligibility refers to the ability of listeners to understand and comprehend spoken words or messages. It measures the clarity and ease of understanding verbal communication across contexts such as public address systems, telecommunications, broadcast media, or live performances. Factors influencing speech intelligibility include pronunciation, articulation, volume, background noise, and the quality of the audio transmission system. High speech intelligibility is the desired outcome to ensure effective communication and minimize misinterpretations.