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Bad Acoustic Design Disrupts Verbal Communication

It can affect the experience of a work space, luxury car showroom, restaurant etc. - any place where verbal interactions are important.

In June, I went to an office in Singapore for a meeting, and experienced some odd things.

  • I was having trouble perceiving the words being said to me;

  • I felt like I was talking extremely loudly and it made me self-conscious

The root of these issues?

Here's the tl;dr version, in order of the above points, of how a poorly designed space might impact communication at your meetings:

1.  IMPAIRED SPEECH PERCEPTION "Long RTs reduce the clarity of the speech and thereby intelligibility." (Source) (RTs = Reverberation Times)

2.  REINFORCED LOUDNESS "Reflected sound that arrives within 35-40 ms of the direct sound...adds to the loudness of the direct sound" (Source) (Note: This can be both good or bad)


In the space I was in, the ceilings were exceedingly high and reflective, creating reverberations that lasted a long time.

Scientists from the University of Kaiserslautern and the Hearing Center Oldenburg in Germany tested groups of 16 participants at a time, seated in 3 rows, in 2 acoustically-different classroom environments, for the difference in the accuracy of their speech perception depending on which room they were in.

They tested children and adults, but for the our purposes, we'll just concentrate on the adults.

Speech perception accuracy dropped by up to 19% when the participants were placed in the room with unfavorable acoustics (longer reverberation time).

Even when individuals were seated right in front, there was at least a 5% drop in speech perception accuracy, caused by the acoustics. In a typical boardroom/conference-room type situation, a person being seated 3 seats away from a speaker at some point is quite likely.

Would you find it acceptable for those people to comprehend only 78% of what is said?

As you'll see in the next point, some reverberations are necessary, so you don't need to cut them all out. Here are some quick and easy fixes:

  • Hang up acoustic panels to absorb reverberations that mask human speech. GIKAcoustics has some fancy "art" panels that won't ruin the look of your room.

  • Put in a carpet! Or at least... don't have a bare concrete floor, if possible.

  • If you must have glass walls, definitely do the first 2 things, or put in some curtains.

2. Reinforced Loudness

In the space I mentioned, I was surrounded by glass, a highly acoustically reflective material, and the floors were made of bare concrete.

To reiterate: "Reflected sound that arrives within 35-40 ms of the direct sound...adds to the loudness of the direct sound"(Source)

Sometimes, reverberation is useful. If you were in a space without it, your voice would dissipate very quickly over a short distance. Well-designed concert halls make use of reverberations to amplify a sound over a distance while taking care to prevent it from adversely affecting the clarity of that same sound.

This was not the case here, and because of the perceived loudness of my voice, I made a conscious decision to speak more softly.

In the same way, more introverted speakers might be uncomfortable in that environment and this could certainly affect the way they communicate.

In an ideal meeting space, people should be able to speak naturally, so that they can concentrate on the task of communicating.



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