Speech Privacy Calculator | FreeAcoustics.tools

What is Speech Privacy?

Speech Privacy measures whether conversations in one space can be overheard in an adjacent space. It combines two factors: how well the partition blocks sound (STC) and how much background noise masks intruding speech (NC).

Privacy Index (PI): PI below 80 = poor privacy (speech understood). PI 80-95 = normal privacy (speech audible but not intelligible). PI above 95 = confidential privacy (speech inaudible). Sound masking can improve privacy without changing walls.

Partition Performance ?

Sound Transmission Class (STC) ? 45

20 30 40 50 60 70

Partition Type

Distance (ft)

Source to listener through partition

Background Noise ?

Background Noise Level ? 40 dBA

25 30 (quiet) 40 (typical) 50+

Background Noise Source

Speech Source ?

Vocal Effort ?

Simplified Privacy Index Formula: PI = 100 − AI × 100 Where Articulation Index (AI) is derived from signal-to-noise ratio across speech frequencies.

Key relationship: PI ≈ STC + BG − SL + 20 log₁₀(d) − 25

Source: ASTM E1130, Cambridge Sound

Privacy Index ?

Enter parameters to calculate privacy.

Privacy Scale

Poor

Marginal

Normal

Conf.

0 60 80 95 100

Articulation Index ?

Received Level ?

-- dBA

Signal-to-Noise ?

-- dB

Word Intelligibility ?

--%

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