Influences on Intelligibility

3-2

Introduction

3-2

Background Noise

3-3

Reverberation

3-4

Distortion

3-5

Microphone Technique

3-5

Measures of Intelligibility

3-6

Introduction

3-6

The Common Intelligibility Scale (CIS)

3-6

The STI Method

3-7

STIpa

3-7

STITEL

3-7

RASTI

3-7

Percent (%) ALcons

3-7

Phonetically Balanced Word Scores

3-7

Practical Measurement of Intelligibility

3-8

Introduction

3-8

Tools for Predicting Intelligibility

3-9

Introduction

3-9

Acoustical Modeling Software

3-9

Chapter 4 Emergency Voice/Alarm Communications Systems

4-1

Introduction

4-1

In this Chapter

4-1

A Typical Emergency Voice/Alarm Communications System

4-2

Parts of an Emergency Voice/Alarm Communications System

4-3

Command Center

4-3

Audio Riser

4-3

Transponder

4-3

Speaker Circuits

4-4

Chapter 5 Regulatory Issues

5-1

Introduction

5-1

In this Chapter

5-1

Audibility

5-2

Tones and SPL

5-2

High Background Noise

5-3

Large Areas

5-3

Intelligibility

5-4

Intelligibility

5-4

Intelligibility Certification

5-5

Chapter 6 Speaker System Design Method

6-1

Introduction

6-1

In this Chapter

6-1

Speaker Design Method

6-2

Introduction

6-2

iv

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Image 6
Tyco 579-769 specifications Emergency Voice/Alarm Communications Systems