Consider Speech Transmission Index for Public Address (STIPA) when design, before it's too late

“It is important to have good speech intelligibility in order for everyone to feel involved.”

Whether in a classroom, seminar, or worship place when someone has trouble hearing you, they will stop listening and become distracted by other things such as speak to someone sitting beside them, boring, sleepy, or do something with their smartphone.

Whether you design a meeting room, worship hall, auditorium and etc, considering Speech Transmission Index for Public Address (STIPA) is a must, before it's too late. And If you want people to be able to hear your voice from the back row of a room, then you have to read this.

Intelligibility

In speech communication, intelligibility is a measure of how well-received and understood your words are. It's affected by the quality of the speech signal of the normal voice level you put in when speaking as well as any background noise and reverberation from within a space where people will be listening. And, for speech over communication devices, the properties of the communication system.

The concept of speech intelligibility is relevant to the multi-discipline fields, including phonetics, human factor, acoustical engineering, audio engineering (for electronic amplification), and audiometry.

Speech Intelligibility Rating in simple method

Speech Intelligibility is a rating of the proportion of speech that is understood. For example, if the speaker says 100 words and we can hear 90 words out of 100 words clearly then we can say the speech intelligibility is 90 percent. The problem with this method is the measuring time will consume a lot of time. For example, if we want to measure the very long speech consist 10,000 or 100,000 words it will take forever.

Speech Transmission Index value to Percentage of Phonetic Balance (PB) word score

What is Speech Transmission Index or STI?

In order to have the objective method of prediction and measurement of Speech Intelligibility, Tammo Houtgast and Herman Steeneken were tasked to carry out a very lengthy series of dull speech intelligibility measurements for the Netherlands Armed Forces. In 1971 they introduced The Speech Transmission Index and was accepted by The Acoustical Society of America in 1980. Their Speech Transmission Index (STI) calculation for prediction and measurement method is a much quicker objective method to the predecessor method.

STIPA (Speech Transmission Index for Public Address Systems) is a condensed and approximate version of the Speech Transmission Index (STI) measurement method for Public Address systems. Within the STIPA signal, each octave band is modulated simultaneously with two modulation frequencies. The modulation frequencies are spread among the octave bands in a balanced way, making it possible to obtain a reliable STI measurement based on a sparsely sampled Modulation Transfer Function matrix. Although initially designed for Public Address systems (and similar installations, such as Voice Evacuation Systems and Mass Notification Systems), STIPA can also be used for a variety of other applications.

Our Acoustic and Audio Engineering team did STIPA measurement at Indonesia Stock Exchange Hall

ALTA Integra Acoustic and Audio Engineering Design Team will ensure your room not only can be used for its purpose but is also an enjoyable experience. Our STIPA (speech transmission index for public address) prediction and measurement method allows you to design a room where people are comfortable enough with the conversation, yet loud enough from speakers still being audible from blocks away."

There's no such thing as an insignificant detail in the world of acoustic and audio engineering design. This is why we at ALTA Integra take great pride in helping architects and other design professionals prevent hearing occupants from having to endure inadequate acoustics while listening or speaking, distracting echoes, or just experiencing something that sounds wrong for one reason or another.

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