Announcements and speeches are for listeners. This page explains the index that shows whether the sound output by the system is easy for the listener to hear or not.
Clarity of sound
If the sound itself is loud enough, it will reach the listener, but simply receiving the sound is a different matter from whether the content of the announcement or speech can be heard.
In this article, "clear sound" is defined as sound that allows the listener to understand the content.
In this article, "clear sound" is defined as sound that allows the listener to understand the content.
STI (The Speech Transmission Index)
Traditionally, the clarity of a sound has been judged by the experience of the person. This makes the criteria for judgment unclear, depending on the individual differences of the listener, the speaker, and the state of the announcement sound source.
If the similarity of the sound that reaches the ear to the original sound (the sound input to the system) is used as an index, it may be possible to measure the clarity of the sound. The index created with this in mind is the Speech Transmission Index (STI). It is an index of the degree to which the system or space distorts the input sound. (Therefore, it is not possible to measure the clarity of the input sound itself.)
The STI value is displayed as a number from 0 to 1. If the sound that reaches the ear contains a lot of unnecessary sounds such as reflected sounds and noise, it approaches 0 (poor clarity), and as the unnecessary sounds are reduced and it becomes closer to the original sound, it approaches 1 (good clarity).
Normally, an STI value of 0.6 or more is considered ideal.
If the similarity of the sound that reaches the ear to the original sound (the sound input to the system) is used as an index, it may be possible to measure the clarity of the sound. The index created with this in mind is the Speech Transmission Index (STI). It is an index of the degree to which the system or space distorts the input sound. (Therefore, it is not possible to measure the clarity of the input sound itself.)
The STI value is displayed as a number from 0 to 1. If the sound that reaches the ear contains a lot of unnecessary sounds such as reflected sounds and noise, it approaches 0 (poor clarity), and as the unnecessary sounds are reduced and it becomes closer to the original sound, it approaches 1 (good clarity).
Normally, an STI value of 0.6 or more is considered ideal.
The following videos have different STIs due to reverberation. The videos contain audio and reproduce the speeches at each time. Please listen with headphones.
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STI: 0.3
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STI: 0.5
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STI: 0.7 |
STI: 1.0 |
STI Improvements
STI is affected by reverberation and noise, so reducing these factors will improve the performance.
See this page for more information.
Also, due to the way STI is calculated, it will decrease with changes in the system transmission process. Sometimes equalization for dramatic effects can cause STI to decrease.
See this page for more information.
Also, due to the way STI is calculated, it will decrease with changes in the system transmission process. Sometimes equalization for dramatic effects can cause STI to decrease.
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