Decibels, explained
The decibel is the unit sound is measured in, and it behaves in a way that trips almost everybody up: it is logarithmic, so the numbers do not add up the way ordinary numbers do. Ten decibels is not twice five. Understanding that is most of what you need to read an acoustic quotation properly.
Why the maths feels wrong
Decibels are logarithmic, which means every 10 dB is a tenfold change in sound energy and roughly a doubling or halving of how loud something seems to a person. So 30 dB of reduction does not mean thirty units quieter. It means a conversation is reduced to about an eighth of its perceived loudness.
It also means you cannot add them. Two people talking at 60 dB each do not make 120 dB. They make about 63.
Reference points that actually help
A quiet library sits around 30 to 35 dB. A normal open-plan office runs 45 to 55 dB with people working in it. Conversational speech at a metre is about 60 dB, and a raised voice around 70.
The useful way to read a pod's figure is as subtraction. Someone speaking at 65 dB inside a pod rated at 30 dB of speech reduction arrives outside at about 35 dB. In an office whose own background noise is 45 to 50 dB, that speech is below the room and cannot be followed. Not silent. Private.
This is also why the same pod performs differently in different rooms. Put it in a silent library where the background is 30 dB and the same 35 dB of leakage is now audible. Nothing about the pod changed.
Where FocusPod stands
Greater than 29 dB speech level reduction across the range, laboratory tested under ISO 23351-1, measured on the assembled pod with the ventilation running. The accessible model tests at 30 dB, Class A, with reverberation under 0.4 seconds. Test reports are available on request for any model you are specifying.
The rest of the terms
Every acoustic term you will meet in a pod quotation, explained the same way.