How the ear hears frequency
The ear doesn't hear frequency in a linear arithmetic way, but logarithmically. So the halfway point between 100 Hz and 1600 Hz isn't 850 Hz as you might expect. This video shows how and why, and finds out the halfway point of the full frequency range of human hearing.
Automated transcript
Today i'm going to give you an insight into how the human ear hears frequency and tell you a secret about the magical frequency of 632 hertz actually 632.45553 learn audio online with audio masterclass audiomasterclass.com in my last video about linear phase and minimum phase filters i used a frequency sweep from 100 hertz to 1600 hertz and talked about the center frequency 400 hertz i'll put a link to that video in the description so in what sense is 400 hertz the center frequency between 100 and 1600 it certainly isn't the average let's start by listening to the sweep all of the audio examples here are between around 8 to 10 seconds long that was exciting wasn't it it's the kind of thing that pleases me i invite your comments so let's listen to 100hz you'll need to be listening on proper speakers or headphones laptop speakers or ebay earbuds probably won't do much for you
and now for hertz
so how can we find the center frequency between 100 and 1600 let's take an average 100 plus 1600 equals 1700. divide by 2 gives 850 hertz here it is
i don't really hear it to me 850 seems a lot closer to 1600 than it does to 100 subjectively but it's the same 750 hertz away from both so this tells us something about the way the human ear works we hear frequency logarithmically rather than arithmetically i'll put a link in the description if you want to look at the maths so how do we find the center frequency logarithmically well i'm sure mathematical geniuses could suggest plenty of ways but i'm going to use what's called the geometric mean to get this i don't add 100 and 1600 i multiply them so 100 times 1600 equals 160 000 take the square root 400 400 hertz so 400 hertz is the center frequency using this method let's listen to 100 400 then 1600 hertz in sequence i'm convinced it sounds halfway to me if it doesn't to you let me know in the comments what you think as i said it's subjective you might by the way have noticed that the jumps are two octaves that's just a coincidence and you can try out this test for yourself with different pairs of frequencies so this brings me to the magical frequency of 632 hertz actually 632.45553 what does it mean well it's the center frequency of human hearing take a moment to absorb that so how do i work this out simple it's that geometric mean again the frequency range of human hearing is normally stated as 20 hertz to 20 kilohertz so if i multiply these 20 times 20 000 equals 400 000 take the square root
632 point
632 hertz is the center frequency of human hearing now i don't expect you to believe me without a demonstration i can't do it the same way as before since it's unlikely your speakers or headphones go as low as 20 hertz so you won't be able to hear it likewise although when you're young you can probably hear 20 kilohertz with age that limit decreases so again probably you can't hear it so what i'm going to do instead is to sweep the tone upwards and downwards from the center of 632 hertz rather than try to explain further let's just listen
now bearing in mind that your speakers or headphones are probably a limiting factor in the low frequencies does 632 sound central to you let's try it another way well it's subjective and you could ask whether it matters i think it matters because the more you understand about audio and particularly how the human ear reacts to sound the better the engineer or producer you're going to be i'm david miller course director of audio masterclass thank you for listening
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David Mellor
David Mellor is CEO and Course Director of Audio Masterclass. David has designed courses in audio education and training since 1986 and is the publisher and principal writer of Adventures In Audio.
@AudioMasterclass replies to @KatrinaDancer: I appreciate your perspective on this. However only an audiologist would be able to give you a reliable response so this time I'll stay silent. DM
@garrettglass8854: Would you know if a cancelling frequency could be found to counter tinnitus? How does noise cancelling work? Would there be a way to find and cancel the intrusive frequencies for people suffering tinnitus? Its ok if you don’t know, just thought this is the place to ask.
@AudioMasterclass replies to @garrettglass8854: This is a question that only a qualified audiologist would be able to answer. Sorry but I'd just be guessing. DM
@the_newvoice: When you were yooung)) (The Killers) I hardly hear 16K. That 850 was much disturbing frequency to me!
@pqpguilhermepqp: Many thanks for your rich content, this is really good for training your ears to know which frequencies to adjust when setting band equalizers.
@AudioMasterclass replies to @pqpguilhermepqp: You're very welcome!
@veronicagorosito187: Hi David! This is so interesting, I think it has to do with the Fletcher-Munson curves and how sensitive is the membrane at that range. Not so sure but common sense tells me it has to do!
I'm just starting sound engineering this year and this is our actual study material (the inner ear and all it's parts). I'll send this video to my teachers, stay safe there, always like your mails and videos 🤗
@AudioMasterclass replies to @veronicagorosito187: Thank you for your comment. Fletcher-Munson probably does have an effect with the lower frequencies seeming less loud. It would take an audiologist to comment further. Hopefully your course will be able to shed more light on this for you. DM
@alanosama4212: What's the name this plugin
@AudioMasterclass replies to @alanosama4212: The spectrograph is a feature of Izotope RX7.
@EgoShredder: Would be interested to hear your thoughts in a video about the 432Hz debate vs 440Hz that we ended up with for music after WW2. I 've done a few blind tests and was very surprised to find I selected 432Hz for every single audio example, and even when 440Hz was used twice in one A<>B example, I immediately identified this. I assumed my ears would prefer 440Hz due to being conditioned with it all my life. 432Hz does not sound technically better, but it does feel a lot better, a sense of well being for want of a better phrase.
@AudioMasterclass replies to @EgoShredder: I don't presently have a thought on 432 vs. 440 but I might consider seeing if I can develop one. Related perhaps is that though I don't have perfect pitch when I sit down to mess around at the piano I wonder why different keys (in the sense of tonality) have different characters; some are my favourites, some not so much? And why when F# seems fairly characterless to me, but if I think of playing mostly the black notes I end up feeling that I'm in Gb which is to me extremely mellow? Perhaps I'm just imagining it all. DM
@EgoShredder replies to @EgoShredder: @@AudioMasterclass You're not imagining it at all, and certain frequencies do indeed invoke different emotional responses. If you analyse different genres or pieces of music, you will begin to notice the choice of frequencies match up with the intentions of the music and the people involved. Very interesting psychological and spiritual aspects.