What is speech intelligibility and speech privacy?

About Acoustics

In environments where information is often transferred via speech, concepts such as speech intelligibility and speech privacy are often mentioned in combination with acoustics and problems with sound.

Think of offices, education, the healthcare sector, the hospitality industry, the retail sector, etc. In all areas where several people come together and talk at the same time.

Would you like to know which acoustic solution is the best in your situation? Then we would be happy to provide you with a tailor-made advice.

Incatro Room Acoustics spraakverstaanbaarheid

What is speech intelligibility?

Speech intelligibility refers to the ability to understand and distinguish speech in a certain environment. It is the ability to hear and understand words, sentences, and conversations, even in an environment with background noise or disturbances. Good speech intelligibility is important in various situations, such as having conversations, listening to a presentation, or taking a class.

Poor acoustics can affect speech intelligibility by reflecting sound and causing poor understanding of words and sentences.

Good acoustics can improve speech intelligibility by reducing sound reverberation and absorbing sound, making speech clearer and clearer.

Improving speech intelligibility

Various acoustic treatments, such as the use of acoustic panels, diffusers, and bass traps, can help improve speech intelligibility in a room.

Incatro has various acoustic panels in its range that improve speech intelligibility. In addition, it also has diffuser panels and an acoustic column that absorbs the sounds in the low frequencies, the ARTbase.

Incatro Room Acoustics spraakverstaanbaarheid AR Tdeskscreen 90mm

What is speech privacy?

Speech privacy is the extent to which conversations and sounds in a room can be heard or understood by people inside (or outside) that room. It is an important aspect of noise control in offices, conference rooms and other public areas, for example.

It is essential that confidential conversations, personal information, and other sensitive information are not heard by people who should not hear it. To achieve this, proper acoustic treatments must be applied to control the sound in the room and prevent it from reaching other areas.

Placing partition walls and (desk) screens with a high sound-absorbing capacity can help to improve speech privacy and ensure the confidentiality of conversations in a room.

What does STI mean?

STI stands for "Speech Transmission Index" and is a measure of speech intelligibility in a certain acoustic environment. This measures how well speech can be understood in a certain room, especially in situations where background noise is present.

The STI measures the ratio between the intelligible part of the speech signal and the total signal, including background noise, echoes, and other disturbances. The result is expressed on a scale of 0 to 1, where 0 is completely unintelligible and 1 is perfectly intelligible.

The STI can be used to assess the quality of the acoustics in different types of rooms. It can also be used to evaluate and compare the effectiveness of different acoustic treatments. A low STI value indicates that speech is difficult to understand, and improvements are needed to improve the acoustics.

Incatro Room Acoustics lombard effect

What is the Lombard effect?

The Lombard effect, also known as the Lombard reflex, refers to the human tendency to raise the voice in noisy environments to remain intelligible to others. This reflex is named after Étienne Lombard, a French physiologist who first described this reaction.

When we talk in an environment with a lot of background noise, we tend to raise our voice volume to get over the noise. This is because our auditory system provides feedback on perceived sound levels, causing us to instinctively raise our voice volume to be heard.

While the Lombard effect can help facilitate communication in some situations, it can also have some negative effects.

  • First, increasing the volume of the voice to get above the noise can lead to voice fatigue or even voice disturbances with prolonged use. This can be especially problematic for people who speak a lot professionally, such as teachers or actors.
  • Second, the Lombard effect can amplify noise in an environment even further. If several people in a noisy environment raise their voice volume to be heard, this can lead to an upward spiral of sound levels. This can lead to an even more uncomfortable environment for anyone in it.
  • Third, the Lombard effect can cause people who are far apart, or who can't see each other at all, to yell at each other to get over the noise. This can lead to confusion, misunderstandings, and unnecessary tension between people.

All in all, the Lombard effect, while it can be useful at times, can also have some negative effects that need to be addressed to improve people's communication and well-being.

Would you rather discuss your options together? Please call one of our experts on +31 85 48 63 380 or request a quote.