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Calcimator

Acoustic Privacy Calculator

Speech privacy class from partition STC and background noise.

Inputs

%

Results

Articulation Index

0

Privacy score (0-100)

100

Effective STC42
Transmitted speech (dB)14.3
SNR (dB)-20.7
Privacy class (1-3)3
STC improvement needed (dB)0
Absorption area needed (sq ft)0
How to Use This Calculator
  1. Enter Partition STC rating, Background noise (dB), and Speech effort (0=normal, 1=raised, 2=loud).
  2. Set Speaker to wall (ft), Partition area (sq ft), and Seal quality (%).
  3. Review Articulation Index and Privacy score (0-100).
  4. Use Effective STC and Transmitted speech (dB) to inform your decision.

What each input means

Partition STC rating
Sound Transmission Class of the wall assembly (typical office: 40-50).
Background noise (dB)
Ambient noise level in receiver room (typical office: 30-40 dB).
Speech effort (0=normal, 1=raised, 2=loud)
Normal voice ~60 dB, raised ~65 dB, loud ~75 dB at 1 meter.
Speaker to wall (ft)
Distance from speaker to the partition wall.
Partition area (sq ft)
Total area of the dividing partition.
Seal quality (%)
100% = perfect seal, lower values account for gaps, outlets, and door undercuts.

What each result means

Effective STC
STC after seal quality degradation.
Transmitted speech (dB)
Estimated speech level reaching the adjacent room.
SNR (dB)
Signal-to-noise ratio: positive values mean speech is audible above background.
Articulation Index
0 = fully private, 1 = fully intelligible. Below 0.05 is confidential.
Privacy class (1-3)
1 = Poor, 2 = Normal, 3 = Confidential per ASTM E1130.
Privacy score (0-100)
Overall privacy rating from 0 (no privacy) to 100 (fully confidential).
STC improvement needed (dB)
Additional STC points needed to achieve confidential privacy.
Absorption area needed (sq ft)
Recommended acoustic panel area to improve masking.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Partition STC rating = 45, Background noise (dB) = 35, Speech effort (0=normal, 1=raised, 2=loud) = 0, Speaker to wall (ft) = 5 = 6 input(s) provided
  2. Calculate Articulation Index
    Articulation Index = ai
    0 = 0
  3. Calculate Privacy score
    Privacy score
    100 = 100
  4. Calculate Effective STC
    Effective STC = stcRating - sealDegradation
    42 = 42
  5. Calculate Transmitted speech
    Transmitted speech = speechAtPartition - effectiveStc
    14.3 = 14.3

Engine last updated . Checked against 3 independently-derived tests — how we verify calculators.

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