The Decibel Meter app from FutureApps samples noises and tells you what the decibel(dB) level is.
The Center For Hearing and Communication Noise states that noise levels are measured in decibels, or dB for short. The higher the decibel level, the louder the noise. Sounds that are louder than 85 dB can cause permanent hearing loss. The hearing system can be injured not only by a loud blast or explosion but also by prolonged exposure to high noise levels.
The fact sheet of the Center For Hearing And Communication states:
Experts agree that continued exposure to noise above 85 dBA over time, will cause hearing loss. To know if a sound is loud enough to damage your ears, it is important to know both the loudness level (measured in decibels, dBA) and the length of exposure to the sound. In general, the louder the noise, the less time required before hearing loss will occur. According to the National Institute for Occupational Safety and Health (1998), the maximum exposure time at 85 dBA is 8 hours. At 110 dBA, the maximum exposure time is one minute and 29 seconds.
The image at the top here is from a a small collection of decibel readings I’ve taken for hand dryers in public restrooms.
Have you noticed how people subject themselves to noise without raising an objection? Of course, perceived or measured noise is a factor of not only the noise the machine puts out, but also the size of the room and the reflectivity or otherwise of the walls, floor, and ceiling.
Tiled surfaces are easy to clean, but they reflect rather than absorb sound. Curtains, on the other hand, are great for absorbing sound. I vote for curtains in restrooms.
I remember having a conversation with an accountant once in a restaurant that was owned by one of his clients. In fact it was a large chain of restaurants, and they had the ‘dining experience’ down to a fine art (and science).
They knew exactly the sound reflectivity of the materials in the restaurant so that they could tweak the subjective experience of the diners so that they didn’t get too comfortable in the restaurant and so stay too long.
Which reminds me that a week or two ago, my wife and I went into a restaurant and we couldn’t stand the noise and walked out without sitting down. We asked ourselves whether we could brave it and just eat – but it was just too clattery and noisy. I wondered how the other diners could stand it.