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Speech Transmission Index (STI) & Rapid STI (RASTI) Intelligibility Calculator

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

Calculated Result
0.39 STI

Speech Transmission Index (STI)

Speech Transmission Index (STI)

0.39 STI

Modulation Reduction Factor

0.315

Apparent Snr Db

-3.4

Speech Intelligibility Rating

POOR / UNINTELLIGIBLE

0.39 — STI

Calculation Breakdown

  1. Applied FormulaModels modulation transfer function (MTF), reverberation masking, and speech-to-noise ratio (SNR) to predict international IEC 60268-16 speech intelligibility.m(F) = \frac{1}{\sqrt{1 + \left(\frac{2\pi F T_{60}}{13.8}\right)^2}} \cdot \frac{1}{1 + 10^{-\text{SNR}/10}}, \quad \text{STI} = \frac{\overline{\text{SNR}}_{\text{eff}} + 15}{30}

Speech Transmission Index (STI) Metric Output

Interactive visualization based on your current inputs

Calculated Value
0.00.30.50.81.0Speech Transmission Index (STI)

What Is the Speech Transmission Index (STI) & Rapid STI (RASTI) Intelligibility Calculator?

This tool computes speech transmission index (sti) & rapid sti (rasti) intelligibility calculator with high precision arithmetic.

How Does the Speech Transmission Index (STI) & Rapid STI (RASTI) Intelligibility Calculator Work?

Models modulation transfer function (MTF), reverberation masking, and speech-to-noise ratio (SNR) to predict international IEC 60268-16 speech intelligibility.

Speech Transmission Index (STI) & Rapid STI (RASTI) Intelligibility Calculator Formula & Variables

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

m(F)=11+(2πFT6013.8)2⋅11+10−SNR/10,STI=SNR‾eff+1530m(F) = \frac{1}{\sqrt{1 + \left(\frac{2\pi F T_{60}}{13.8}\right)^2}} \cdot \frac{1}{1 + 10^{-\text{SNR}/10}}, \quad \text{STI} = \frac{\overline{\text{SNR}}_{\text{eff}} + 15}{30}

Models modulation transfer function (MTF), reverberation masking, and speech-to-noise ratio (SNR) to predict international IEC 60268-16 speech intelligibility.

How to Use the Speech Transmission Index (STI) & Rapid STI (RASTI) Intelligibility Calculator

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

Step-by-Step Example Calculation

Speech Transmission Index (STI) & Rapid STI (RASTI) Intelligibility Calculator Example

Input Values:

reverberationTimeRt60S:1.4
signalToNoiseRatioDb: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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