What is the difference between STC ratings and DBA ratings?

    I am looking at a medical tenant improvement that the designer has stated needs a DBA rating between the exam rooms. I am familiar with STC ratings and have tables for their construction. I am not familiar with DBA or how it equates with STC. Please advise.

    0  Views: 5120 Answers: 1 Posted: 10 years ago

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    STC: A partition is given an STC rating by measuring its Transmission Loss over a range of 16 different frequencies between 125-4000 Hz. 125-4000 Hz is consistent with the frequency range of speech. The STC rating does not assess the low frequency sound transfer. Special consideration must be given to spaces where the noise transfer concern is other than speech, such as mechanical equipment or music.

    DBA: On the decibel scale, the smallest audible sound (near total silence) is 0 dB. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful than near total silence is 20 dB. A sound 1,000 times more powerful than near total silence is 30 dB. Here are some common sounds and their decibel ratings:
    Near total silence - 0 dB
    A whisper - 15 dB
    Normal conversation - 60 dB
    A lawnmower - 90 dB
    A car horn - 110 dB
    A rock concert or a jet engine - 120 dB
    A gunshot or firecracker - 140 dB

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