Showing all 1 result


ISO 23351-1:2020 testing

ISO 23351-1:2020 standard measures speech reduction levels of phone booths, work pods, and other furniture ensembles and calculates a figure called “speech level reduction.” (decibels/dB).

Speech level is measured outside and inside the booth. The measurements calculate the decibel amount of speech level reduction provided by the product.

ISO 23351 classes pods and booths as  A+, A, B, C, or D in accordance per amount of speech level reduction.

The booth/ pod must reduce at least 25 decibels/dB of sound to guarantee speech privacy in the typical office.

ClassSpeech level reduction (DS,A)Speech privacy guaranteed?
A+> 33 decibels/dBFor recording (fire alarms may not be audible)
A30-33 decibels/dBYes
B25-30 decibels/dBYes
C20-25 decibels/dBDepends on background noise level
D15-20 decibels/dBLimited

For example: if you are speaking inside a booth that’s Class B. (your speech averages 60dB). The Class B booth reduces speech levels by up to 30dB.

For reference, 30 decibels is about the power of a whisper.

Background noise for the vast majority of offices is at least 40dB. So the 30dB of sound that seeps outside the Class B work pod in this scenario will be masked by the office’s background noise. In short, none of your speech will be audible or intelligible to those outside.

Class A+, A, and B pods all reduce speech levels by at least 25dB. Say you’re speaking (again, at 60dB) in a pod that reduces your speech by at least 25dB. A maximum of only 35dB of your sound will seep outside of the booth onto the floor. This 35dB will be, in turn, inaudible and unintelligible on the typical office floor (given its 40dB of background noise which masks said 35dB).