when people talk in a low voice, i don’t notice it. but when they whisper it sounds harsh and noticeable.
In: Biology
If you were to record the two, and compare the sound waves side by side, you would see that the whisper contains more high frequency content and the low speaking contains more low-mid frequency content. So it’s less about the volume and more about the frequency you’re hearing.
For the same reason that people who are hard of hearing often talk really loud, or even shout: people need to be able to hear *themselves* when talking. So while they are *trying* to actively keep their voice low, they still need to be able to hear it, which means they’re talking far louder than they think they are. My mother has partial deafness on her left side, and in places like the doctor’s waiting room when we’re talking quietly, she talks far louder than I do, and much louder than she thinks she does.
If you are to measure both with a spl meter, talking it’s generally louder. However, the silence of whispering is much more prominent to the human senses. It doesn’t blend in to the background the way quiet conversation does, so it is more likely to be noticed or distracting.
Human hearing is non linear, meaning we don’t hear all frequencies at the same level. In fact, for humans to hear low frequencies at the same level as higher frequencies it requires much more amplitude. So why is this important? Human hearing is most sensitive at around 3000 Hz or 3 kHz. Unsurprisingly, you may also notice that grass or leaves rustling in a breeze are quite easy to hear, those sounds are in that general range. It’s a natural adaptation to the world around us. So whispers are also in this range, really anything that has an s or t sound. Those who are beginning to lose their hearing are actually losing those higher frequencies, basically it starts to sound like someone is talking to you through a blanket, muffling all of the detail you would get in those higher frequencies.
Fun fact, when bell laboratories were designing the telephone, due to bandwidth issues they couldn’t replicate all frequencies through a telephone line. So they sought out to find the range at which humans can hear a conversation with the least bandwidth. They discovered what is known as the Fletcher Munson curve. Again, the telephone for decades was centered around that same frequency. Generally, on older phone lines what you are hearing is a range from around 700 Hz to 5 kHz.
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