Understanding Audio Frequency Response & Psychoacoustics

Frequency response measurements in audio are very common but it takes proper knowledge of psychoacoustic (how we hear sounds) to interpret them and realize what is an audible concern, and what is not. In this video I explain how you should interpret such measurements for headphones, speakers and room.

Article Referenced:

[PappLacc]

Ive learned more in this 20 minutes about FR measurements, than from all other videos/guides from the past years.. thanks again for the great video Amir!

[fwabble]

What an excellent video, I've learnt so much and it makes pefect sense. Explained very well.

[MrKallemyran]

i'm new to the forum and a complete noob in this field but i have studied both electronics and biology a lifetime ago so i really appreciate the way that you always make the connection between both fields (Psychoacoustics=biology in my mind). That connection is often missing in many analyses out there, which can be very missleading. Thank You!

[JurajHatina]

Excellent as always Amir! Thanks for the deep dive again.

[Shahzad-Khan]

I can listen to you all day. Your soothing voice and plethora of knowledge makes a deadly combination

[upreid]

This is terrific Amir - so helpful. I've been 'into' audio for 40 years and each of your videos makes me realise how much BS I have absorbed when, had I known better, all the while genuinely useful science like this was out there.

[christakimoto]

Super informative. I've been viewing these Frequency Response graphs for some time but just now starting to appreciate how to understand them! Thanks Amir!

[Droog.]

Hold on a second! @7:20 you discuss small changes at ~250Hz are perceptible but the same width (on the graph) wiggles at 15kHz are not perceptible (due to ERB), but AND THIS IS A BIG BUT the plot is a log scale so the wiggles at 250kHz are about 30Hz apart (peak to peak) and the wiggles at 15kHz are about 4kHz apart (so ~100 x as wide on a linear scale) From the wikipedia equation @6:00 the ERB at 250Hz is ~27Hz and the ERB at 15kHz is ~1.6kHz. So, yes ERB sensitivity decreases with Hz but not at the rate you imply. In fact from these rough eyeball calculation the wiggle at 15kHz will be perceived more clearly than the one at 10Hz. That is just maths. So, in fact the standard log scale freq. response curve does in fact give a reasonable (for comparison sake) approximation of perceived fluctuations across the audible range. Very interesting subject though. Thanks for posting.

[astcal]

great mini tutorial! as always, YOU ROCK Amir!

[berlyfredy]

Thanks for explaining psychoacoustics in a reasonably easy to understand way.

[johnlim]

Good day Amir...avid fan all the way from the Philippines. Thanks so much for the reviews and the knowledge that you give...keep it up and stay safe.

[anacoustician]

Should be retracted.
7:14
"...variations here (around 240Hz) is far more audible because hearing bandwidth, ERB is very narrow"
"...whereas, when you get up here (around 15kHz), you can see these little wiggles, your ERB is big chunk over here...these little peaks and valleys are never heard"
"the same peaks and valleys here (around 240Hz) are (can be) audible."

First of all, Amirm is clearly saying the word "same peak" on the log axis, otherwise, it does not look the same at all.
And well, ERB's 51Hz bandwidth on 240Hz corresponds to about 0.306 oct and 1640Hz bandwidth on 15kHz corresponds to about 0.158 oct, obviously former is greater on the log axis.
So, if you see the "same peak" on 240Hz and 15kHz on the log axis, the former has less possibility of audibility.

I'm very sorry to say, because I'm paying respects for his efforts, but this time, I should say Amirm is completely wrong.

[YoYo-uhxj]

I was getting tired of hearing it's good for the price everywhere. Regardless of price is it good or bad, plain and simple. ASR keeps the recommendation simple and straight to the point. I can respect that.

[teashea]

Brilliant presentation ---- thank you so much - you the Man

[daleromney]

This is a GREAT video. Thank you. I am an EE, and this really appeals to my desire to measure and understand the measurements. It also is great for all those that want to claim that we do not understand sound and cannot measure all the things that affect how sound is perceived. Great video. I learned watching this video, and feel like I have been looking for this explanation for a long time.

[vkvedam]

Another excellent one Amir! Keep them coming.

[MrSilviut]

Actually, this was really informative and explains why bass management is so important. Thank you, Amir.

[HeliBenj]

Thanks a lot for your work Amir, your channel is proving to be an invaluable resource for us that want to understand more about audio reproduction and perception

[eddiejennings]

Hello Amir, I have a many-year background in digital signal processing and acoustics and have a love for audio passed on from dad. I really appreciate the added psychoacoustics smoothing background and practical room and speaker equalization information- in a very palatable way. I will review your site more often. Great job, sir in helping to set a higher bar for those hobbyists who want to be more scientifically informed.

[squidcaps]

Correction filters need to be split into few groups. 20-100, 100-1k and 1k to 3k. Above 3k it matters less and like said here, our ability to hear them is not great... and measurements just start to have more and more random elements the higher we go, and our methods of fixing small things in high frequencies is also not great. 20-100Hz is its own problem and we need this area to be smooth. Peaks and valleys here will affect the actual notes, you can have A1 to be loud and E1 to barely be audible. 100-1k is maybe the best range to fix, the impact is great but also our filters can do a lot. 1k-3k is starting to get more difficult to fix narrow problems but our hearing is quite sensitive.

One school of thought is that when you have made big changes, halve them all.. When tuning speakers with ears this works the best, you fix the curve as best as you can and then you halve the amplitude of the changes.