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Speech Intelligibility Index (SII & STI / RASTI) Calculator

Easily calculate and compute speech intelligibility index (sii & sti / rasti) calculator with accurate equations, live formulas, and expert guidance.

Calculated Result
0.76 STI

Speech Transmission Index (STI, 0 to 1)

Speech Transmission Index (STI, 0 to 1)

0.76 STI

Speech Transmission Index S T I

0.7578092081346325

Raw Snr Db

20

Effective Snr Db

7.734276244038975

Reverberation Penalty Db

12.265723755961025

0.76 — STI

Calculation Breakdown

  1. Applied FormulaEstimates room speech intelligibility (STI / RASTI / SII) based on speech-to-noise ratio (SNR) and room reverberation time (RT60) per IEC 60268-16 standard for classrooms, lecture halls, and PA systems.\text{STI} \approx \frac{(\text{SNR} - 10 \log_{10}(1 + \frac{T_{60}}{0.05})) + 15}{30}

Speech Intelligibility Index Metric Output

Interactive visualization based on your current inputs

Calculated Value
0.00.30.50.81.0Speech Transmission Index (STI, 0 to 1)

What Is the Speech Intelligibility Index (SII & STI / RASTI) Calculator?

The Speech Intelligibility Index (SII & STI / RASTI) Calculator computes results using established domain formulas, verified conversion factors, and user-entered parameters.

How Does the Speech Intelligibility Index (SII & STI / RASTI) Calculator Work?

Estimates room speech intelligibility (STI / RASTI / SII) based on speech-to-noise ratio (SNR) and room reverberation time (RT60) per IEC 60268-16 standard for classrooms, lecture halls, and PA systems.

Speech Intelligibility Index (SII & STI / RASTI) Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

STI≈(SNR−10log⁡10(1+T600.05))+1530\text{STI} \approx \frac{(\text{SNR} - 10 \log_{10}(1 + \frac{T_{60}}{0.05})) + 15}{30}

Estimates room speech intelligibility (STI / RASTI / SII) based on speech-to-noise ratio (SNR) and room reverberation time (RT60) per IEC 60268-16 standard for classrooms, lecture halls, and PA systems.

How to Use the Speech Intelligibility Index (SII & STI / RASTI) Calculator

  1. Enter your parameters into the designated input fields to calculate the result immediately.

Step-by-Step Example Calculation

Speech Intelligibility Index (SII & STI / RASTI) Calculator Example

Input Values:

speechLevelDb:65
ambientNoiseLevelDb:45
reverberationTimeSec:0.8
Worked Steps: Sample evaluation based on standard reference conditions.

Understanding Your Result

The calculated primary figure indicates the optimal or required STI.

Factors That Affect the Result

  • Measurement tolerances, operational variance, and real-world conditions.

When Should You Use This Calculator?

  • Everyday budgeting, technical homework, professional estimation, and household projects.

Assumptions & Limitations

  • Assumes standard atmospheric or environmental parameters unless specified.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Double-precision IEEE 754 arithmetic with validated empirical constants.

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