Well, roughly speaking, sound pressure (dB) decreases by 6 dB with the doubling of distance.
Was going to point this out as well.
I found this link -
Rotary Hand Bell - Bell sounds 60db alarm up to 35 meters - [HS-RHB] - which suggests a fire bell sounds at 60 dB at a distance of 35m (114.8 feet - for ease of use, I will call that 120 feet). At 60 feet, then, that bell would be 66 dB, at 30 feet it would be 72 dB, at 7.5 feet, it would be 78 dB, and at about 3 feet (arm’s length) 84 dB.
Noise levels of everyday sounds says this is between an alarm clock and a subway train.
The same site says a whisper at 5 feet is 20 dB and 0 dB is generally considered the absolute lowest audible dB level in perfect conditions, anything under about 20 dB is likely to be swallowed by background noise (breathing is 10 dB per the site linked above). So if we work thinks backwards from that 20 dB whisper at 5 feet, we are looking at 26 dB at 10 feet, 32 dB at 20 feet, 38 dB at 40 feet, and 44 dB at 80 feet would all sound like a whisper. So a 40 dB alarm would be basically inaudible at 60 feet away. Of course, in an occupied room, it would be drowned out by ambient noise (48+ dB) even if you were a foot from the origin.
The human voice ranges between 50 and 70 dB per
What Is The Decibel Level Of The Noise In A Typical Classroom so that would mean if the alarm spell generates a tone that is a little softer than a human voice it would only be audible for about 60 feet as per the spell, less in a noisy environment.
But… magic. Not physics. We don’t have different ranges for the spell depending on ambient noise. Therefore to my mind, the spell does not produce sound waves, rather it produces an either an audible glamer in the minds of those within the 60’ radius or causes their eardrums to vibrate at an effective 70 or so dB regardless of how far from the origin they are… as long as they are within 60’. At 61’, the magic can’t reach you and since there is no physical sound wave you get nothing,
In other words, stop trying to mix magic and physics.
(At some point we have to accept that the D&D world is not quantized at the Planck length and time… it is basically quantized at the 5’ cube level for space and the “six seconds (one round)” level for time anyway so there is no such thing as 60 vs 61 feet - if you are more than 60 you are at least 65 feet).
