A few years ago I received a phone call from a local retirement community. The director of resident services had received multiple complaints regarding the poor acoustics of their main dining room. After a brief discussion, it was clear that the complaints were related to the residents’ inability to understand each other, even when sitting at the same table. This problem is typically due to excess background noise and sound buildup, and so I immediately assumed (mistakenly) that this project would be a cinch. The director of resident services asked me to come by, evaluate the acoustics, and recommend some modifications that would remedy the problem.
Many dining facilities lack adequate acoustical absorption to control the sound generated by occupants during mealtimes. But even in well-treated facilities, many seniors may have difficulty understanding one another’s speech.
When I arrived, I was brought into a large room with high ceilings and a beautiful view of the nearby, bucolic setting. I saw some signs of acoustically absorptive finishes, but not many, and so I assumed (again!) that the room would need more acoustical absorption. As many of us know from experiences at restaurants, many dining facilities lack adequate acoustical absorption to control the sound generated by occupants during mealtimes. This is typically a straightforward problem to address: add acoustically absorptive finishes! Again, I thought I would be able to fix this problem in no time.
I can easily take a few measurements, do a few calculations, and recommend the amount and type of acoustically absorptive treatment needed to reduce sound buildup in a dining facility. This won’t necessarily make the room quiet during mealtimes, but it should make it so that the conversation at your table is louder in comparison to the sound from others’ conversations. Voila! Problem fixed, right? Not quite …
I measured an indicator of sound buildup: the reverberation time. To my surprise, I found that the reverberation time was already quite good.
Puzzled, I stayed for dinner to measure sound levels and to personally observe the acoustics during a meal. I found that I could understand others quite well.
Upon talking to some of the residents, it seemed that those residents with hearing loss, and particularly those who used hearing aids, experienced poor acoustics in the room. All of a sudden, I realized that there might be something that my 32-year-old ears were unable to capture: the difficulty in deciphering speech when suffering from hearing loss.
Once I came to this realization, the problem became clearer to me. People tend to lose high frequency hearing first. A lot of speech content is in the high- and mid-frequencies, particularly, the “unvoiced consonants”. This makes conversations very challenging for those with hearing loss. Imagine trying to tell the difference between “cat”, “sat”, and “pat” without being able to hear “c”, “s”, “p”, or “t”. It’s impossible.
What I realized was that the occupants of this dining room were not experiencing excessive sound buildup, rather they were experiencing a lack of acoustical support at high frequencies. Fortunately, this problem is treatable. To provide support for particular speech frequencies, you can install mid- and high-frequency reflectors. These elements should reflect sound at high-frequencies, emphasizing high-frequency content, and may or may not absorb sound at lower frequencies, de-emphasizing low-frequency content. To be effective, these reflectors need to be located close to the table.
From what the facility has indicated, they have tried dining with temporary reflectors and found the technique to be successful. They are now working out how to install these reflectors in a way that complements the room’s design aesthetic.
Alicia Larsen is a Senior Acoustics Consultant at Acentech. She has extensive experience with senior care facilities and is a regular contributor to our blog. To learn more about Alicia, click here.