These are different measurement standards that produce non-comparable numbers. ISO 23351-1 DS,A is an internationally standardised A-weighted speech level reduction metric, tested under specific laboratory conditions defined by the ISO standard. It directly measures how much the pod reduces speech-frequency sound levels — the sounds responsible for the ISE. NIC (Noise Isolation Class) is a single-number rating system primarily used in the US for partitions and walls, measured using a different methodology and frequency weighting. A pod claiming “30 NIC” and a pod claiming “DS,A 29.4 dB” are not making the same claim and cannot be directly compared. When evaluating acoustic pods, always ask for ISO 23351-1 DS,A from a named accredited laboratory. HIGHKA’s DS,A = 29.4 dB is independently verified by SGS.