How would it affect a human to suddenly hear like a cat?

Question

A typical cliche that is often used in Anime is that anthropomorphic cats exist. These are basically humans with cat-ears and a cat-tail (see Plausibility of the Japanese Nekomimi for a fitting picture).

I want to know how it would affect a human if he was suddenly able to hear like a cat.

I want to focus on the frequency range cats can hear. In this regard Wikipedia states that "Cats have excellent hearing and can detect an extremely broad range of frequencies. They can hear higher-pitched sounds than either dogs or humans, detecting frequencies from 55 Hz to 79,000 Hz, a range of 10.5 octaves, while humans and dogs both have ranges of about 9 octaves. Cats can hear ultrasound, which is important in hunting because many species of rodents make ultrasonic calls." Other points regarding the ears of cats, like steerable ears, can be ignored.

For this question we will assume a crazy bio-engineer in the distant future manages to operate a normal adult human, removing his human ears and instead giving him cat-ears similar to those of a Maine Coon, just bigger. This human acquires the same hearing capabilities as this type of cat. Other changes that would be necessary to make this plausible can be ignored. After the operation the human goes back to his normal life and is monitored by the crazy bio-engineer to see the results of this little test.

To make it possible to make assumptions about the environment we will stick to the present. This means that the human race will only focus on bio-engineering and not change in any other aspect. Therefore it will be normal for other people if this human disappears for some time and comes back with cat-ears, but technology, culture, etc. will (except for the acceptance of such bio-engineered humans) remain the same as today. The setting is Europe and we will imagine this human to be a middle-class white-collar worker.

This question is different from others like Plausibility of the Japanese Nekomimi because I don’t want to create a new race which is born with such capabilities and therefore accustomed to them.

I want to know what would change for a normal human if he suddenly got such capabilities and how this would affect his everyday-life.

Answer 1

The human will be able to hear a variety of additional, but largely unimportant sounds, at the expense of poorer ability to interpret important sounds, particularly speech. He will be much more aware of his or her environment, at the expense of difficulty with social interaction due to having a hard time communicating.

The problem has to do with the issue "frequency discrimination". That is, how well can you tell apart two similar frequencies. Cats, having their hearing range spread over many more frequencies, are much poorer at telling apart two nearby frequencies. This is particularly important in speech, where such cues are critical for understanding what word is being spoken.

This also is an issue for detecting where a sound is coming from. Due to our large head size, humans are much better-suited for picking out interaural time differences, which are differences in the arrival time of sound between the two ears. The catch is that ITDs are only useful at low frequencies. The human brain's sound processing is laid out in terms of frequency, so with no other brain changes the sound location system will be completely messed up and a large portion of it will be totally useless. Even if the brain was also changed, you still have the issue that your subject has less of his auditory system dedicated to the necessary low frequencies. This is a major problem, since being able to tell where sound is coming from is essential to understanding speech in noisy environments.

Overall, your subject would have a really, really hard time understanding speech, especially at parties, or on the subway, or while walking near a busy street, to such an extent that he or she will likely avoid many social encounters.

Answer 2

This is an "in addition to" answer, as BlackCat's answer has good points, but I started writing a comment and moved to an answer due to length.

So, the first extra issue is also sensory overload and nuisance. Basically, human society is built for human hearing ranges. There are some things that will have undoubtedly ultrasonic noises that might be strong enough to cause nuisance in animals that can hear them. Some areas might be positively painful for any creature with that kind of hearing range to go into and there might be certain sounds that an individual with that hearing just could not cope with, leaving them rolling around on the floor in agony while people look on in puzzlement.

Equally, it might cause a lot of nuisance if you could hear every mouse squeak and suddenly realise your building is infested with mice you can hear behind the walls or your garden is a major hive of nighttime wildlife activity crossing through and around. It might affect your sleeping, or you'd just look odd, suddenly swiveling to follow sounds that no one else can in a conversation.

With a different hearing range, there's also the issue of responding to sounds. For example, it's been said that cats respond better to women than men because men have lower pitched voices and therefore are harder to hear. If that's true, then that would have a significant impact on the social functioning of your person with cat ears.

However, there might also benefits in some ways. For example, there are mice on the London Underground which are supposedly a different type of mouse because their ultrasonic squeaks are tuned such that they can speak (or should it be squeak?) quite clearly to each other even over the noise of tube trains, which are quite loud and deafening at the best of times.

There might also be an adjustment period while the person gets used to things, especially if their hearing is more directional due to the ear-turning thing, and everything might be overload at that point.

While that's not all, the human would also have to deal with suddenly having more body-language with animals, particularly cats, who use ear position as a way of communicating feelings. They'd have to be careful about how their ears are poised if they're trying to deal with a cat especially.

Answer 3

In addition to what TheBlackCat and aphenine said. TheBlackCat said this, which is important:

The problem has to do with the issue "frequency discrimination". That is, how well can you tell apart two similar frequencies. Cats, having their hearing range spread over many more frequencies, are much poorer at telling apart two nearby frequencies.

Compared to a human, you will be practically tone deaf. You won't be able to tell apart so many notes in so many songs that they will not make sense to you anymore.

Imagine never being able to enjoy music again.

Another thing: some audio devices such as CD players, as well as audio file formats such as MP3 filter out sounds higher than regular human hearing frequencies in order to save up storage space. So if you hear something firsthand and then hear a recording of it, depending on the media, you will notice quite a difference. You might see a dognon TV and think "hey, that's not what a dog sounds like at all!" A human analogy would be watching Guns'n'Roses live and hearing everything, but then when hearing a recording it would be as if Slash and Axl were never there.