The video above is an audio frequency test, which is measured in hertz and is determined by pitch. It is acknowledged that the human ear is capable of detecting a wide range of sound frequencies, approximately ranging between 20 Hz and 20 000 Hz. Sound frequencies below 20 Hz are known as infrasound and sounds above 20 000 Hz are known as ultrasound.
Take the test and see how high you can go!
While we humans are pretty good when it comes to sound, we are not alone in our ability to detect a wide range of frequencies. In fact, dogs can detect frequencies as low as 50 Hz and as high as 45 000 Hz. Cats can detect frequencies as low as 45 Hz and as high as 85 000 Hz. These are impressive figures, but the next few animals/creatures are even more exceptional. The most studied animal when it comes to sound is the dolphin, specifically the bottlenose dolphin, which can hear as high as 150 000 Hz. Yes that’s right 150 000 Hz. But there’s one other mammal that can achieve an even higher frequency level. The bat. Bats can produce and hear frequencies as high as 250 000 Hz, being nocturnal creatures they rely solely on sound to navigate. Now that’s remarkable.
So why am I talking about sound frequencies?
Well it’s to do with microphones. Like the human ear, microphones have a limited range of hearing capabilities. However the frequency response is dependent on the microphone type and microphone model.
The Omni-directional microphone has a frequency range of 20 Hz to 18 000 Hz. The Stereo microphone can pick up frequencies ranging from 30 Hz to 20 000 Hz. The Unidirectional microphone can respond to frequencies between 70 Hz and 18 000 Hz.
Although the differences in frequency responses are small, it is still important to take note. This is because some microphones will cut out at a certain frequency, while others will be capable of picking it up. So if you are in a shoot and you require the microphone to pick up a specific sound, and you get into post-production to find that it doesn’t exist, it might be that the microphone failed to pick it up. On the other hand, you can specifically aim to cut out certain sounds, if you organise the shoot to pick up a specific frequency range. This would be useful in avoiding unwanted ambient noise.