Understanding Audio Frequency Response & Psychoacoustics

[@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!

[@AudioScienceReview]

That's great to hear. Thanks for watching and commenting.

[@dingdong2103]

This video also explains why large panel speakers are so awesome, their response in room is close to the anechoic response in near field.

[@rishelbhallabhatia1672]

@@AudioScienceReview can you please suggest equaliser measures for b & w 706 s2 speakers . I get ear fatigue while listening to them. Thanks for you help in advance

[@fwabble]

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

[@stephenoverton8352]

No such word as "learnt"...LOL.

[@erics.4113]

@@stephenoverton8352 the learning continues

[@Shahzad-Khan]

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

[@antoniohernandez6590]

Amir ASMR?

[@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!

[@AudioScienceReview]

Ah, it is so nice that you see what I am trying to do here. The two worlds can be so abstract but very useful connections can be made. And indeed are critical to understanding what we are doing with measurements.

[@MrKallemyran]

​@@AudioScienceReviewYes I clearly see it and it makes me smile. In fact.. In the world of science, huge leaps can be made if scientists let go of their prestige and walk over to another room where a completely different field is being analysed.. Chances are that it could lead to an aha moment that could benefit both fields..if not the whole society.I once attended a lecture where the lecturer euphorically explained that when doing his research on blood vascular system and its scaling in volume and pressure with body size of different organisms he had come across the mathematics from a friend who worked as an engineer , constructing water systems for large buildings. Turned out..almost the same formulas could be used in both fields and evolution had "solved it" by using variation in offspring traits..and time :-)

[@JurajHatina]

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

[@andysummersthxcinemaandmyc7748]

Like submarine sub bass movie do you feel like being under water? does the abyss make you feel the too much pressure or don't have can afford pro cinema THX?

[@christakimoto8425]

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!

[@berlyfredy7153]

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

[@AudioScienceReview]

My pleasure. Not everything in psychoacoustics is relevant to audiophiles so I hope to over time distill all of them and show the application.

[@dogbucket]

@@AudioScienceReview That will be great. Looking forward to it.

[@YoYo-uh3xj]

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.

[@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.

[@johnlim7720]

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.

[@AudioScienceReview]

Hi John. Thank you so much! Appreciate you watching and commenting.

[@astcal]

great mini tutorial! as always, YOU ROCK Amir!

[@AudioScienceReview]

Thank you kindly. Had a bit of a dry spell as to what topic to cover and this afternoon it just hit me to go over frequency response in this manner.

[@teashea1]

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

[@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

[@AudioScienceReview]

Thank you Ben. Very kind of you. When I started this channel I thought I would just do videos. I started doing these videos as a way to make it easier to understand the reviews, not realizing that they have value beyond that. So I will keep doing them with these words of encouragement.

[@Droog.28]

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.

[@daleromney6062]

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.

[@MrSilviut]

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

[@squidcaps4308]

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.

[@jefierro]

Thanks Amir, always with the best explanation of complex subjects

[@AudioScienceReview]

Ah, you are very kind Jorge. Thanks for watching.

[@vkvedam]

Another excellent one Amir! Keep them coming.

[@AudioScienceReview]

Will do Ven. Thanks for watching and commenting.

[@eddiejennings5262]

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.

[@anacoustician7979]

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.

[@mengshilim7364]

Another excellent teaching video.

[@AudioScienceReview]

Ah, you are very kind.

[@kimmidgley5525]

Hi Amir. Thanks for the effort that you put into sharing this science. I had a thought about the comparisons of SPL fluctuations (around 7:50 in your video) and a further consideration is that when you look at the fluctuations (in your JBL example) around 230 Hz they span about 50Hz but the fluctuations at 13000Hz span maybe 3000Hz, owing to the logarithmic x-axis. Perhaps the fluctuations "seen" to be about the same size are actually close to equally audible, or at least the fact that the frequency response is plotted on a log scale would tend to "balance things out again" in relation to ERB?

[@kimmidgley5525]

I see a comment below where Drew Wilson says something that gets at what I am trying to say, but probably far more eloquently.

[@lummert]

I was just about to point that out too. I tried to compose (but failed) an illustration of filter bandwidth superimposed on a random FR measurement. But in conclusion: The filter bandwidth of around 25 Hz at 10 Hz will appear considerably wider than the filter bandwidth of close to 100 Hz at 640 Hz, which in turn will appear wider than the filter bandwidth of around 1 kHz at 10 kHz - provided we use the usual logarithmic scale for the FR graph (as in the JBL example).

[@TheSputnikman]

Thank you so much for this video and sharing your knowledge in this format, Amir! It is a great pleasure to learn from you and your experience. Very best greetings from Latvia! ^_^

[@motorradmike]

Excellent demonstration of psychoacoustics, Amir. Learned a lot. Thanks.

[@nickgoogle4525]

The statement between the lines is that FR needs to be smoothed according to our hearing. Surely those smoothing methods have been developed or are in development. And indeed I found that REW offers three methods, one of them being ERB-based. That would sound like a good choice. But two other (psychoacoustic and variable smoothing ) sounds it would try to do the same. The documentation suggests to use variable (VAR) smoothing when this will be the basis for EQ. Have you (or someone else here) tried the different methods? Why are there three? For different hearing conditions? Or is one better than the other? REW documentation excerpt: Variable Smoothing Ctrl+Shift+X Psychoacoustic Smoothing Ctrl+Shift+Y ERB Smoothing Ctrl+Shift+Z Apply a smoothing filter to the current channel. Repeating the action removes the smoothing. Variable smoothing applies 1/48 octave below 100 Hz, 1/3 octave above 10 kHz and varies between 1/48 and 1/3 octave from 100 Hz to 10 kHz, reaching 1/6 octave at 1 kHz. Variable smoothing is recommended for responses that are to be equalised. Psychoacoustic smoothing uses 1/3 octave below 100Hz, 1/6 octave above 1 kHz and varies from 1/3 octave to 1/6 octave between 100 Hz and 1 kHz. It also applies more weighting to peaks by using a cubic mean (cube root of the average of the cubed values) to produce a plot that more closely corresponds to the perceived frequency response. ERB smoothing uses a variable smoothing bandwidth that corresponds to the ear's Equivalent Rectangular Bandwidth, which is (107.77f + 24.673) Hz, where f is in kHz. At low frequencies this gives heavy smoothing, about 1 octave at 50Hz, 1/2 octave at 100 Hz, 1/3 octave at 200 Hz then levelling out to approximately 1/6 octave above 1 kHz.

[@gsm9551]

Awesome topic and video! Thanks!

[@AudioScienceReview]

Thanks George. :)

[@ericharrelson2045]

Amir, well done. I learned a few things on this one; gonna have to watch a couple of times for it to sink in completely.

[@AudioScienceReview]

Thanks for watching Eric. Yes, re-watching will help. I myself often read the some research papers many times and still find more information in them.

[@martijnbos9873]

Everybody interested in audio should be subscribed to your channel

[@2by3]

Very interesting. This explains why even very low THD at lower frequencies can be easily heard.

[@Another_Audiophile]

Great having reviews with measurements. It helps a lot to identify a badly designed piece of equipment. As a scientist my self I can tell that this is everything but science. Let not mistake what science is.

[@jeffmeier1663]

Thank you for this video. I have seen way too many DIY folks and software solutions apply a very large number of corrections to speaker frequency response with negative consequences. I believe this results in problems like you express along with the fact that these measurements can change dramatically with minor changes in microphone positioning. It is important to deal with problems that apply to the entire listening area and not a single microphone position. I also think large positive adjustments in equalization can result in increased distortion if the speaker struggles to handle the increase in power. I would suggest the use of wideband pink noise for observer evaluation of frequency response along with a wide selection of recorded sounds. Wideband pink noise will excite all frequencies over a short time frame while recordings are going to be more limited in content. This of course assumes the observer has some experience with what wideband pink noise should sound like. The only way to get that experience is to start using it on a regular basis. I have found that very narrow band errors of large positive magnitude at high frequencies can be very audible. I had a surround speaker in one application that had a very narrow band resonance at around 10 kHz and a width of no more than 100 Hz that was obvious as soon as I played something that excited that frequency. It was a sound that wanted to drill a hole in my head. Luckily I was able to remove it with a very narrow filter of about -30 dB magnitude. With that filter I was not able to hear any problem with the speaker. I was also not able to tell that the frequency was essentially not present in that speaker. I find large positive errors in frequency response of narrow bandwidth to be much more objectionable than negative errors. I think this is because most observers do not know what they are missing versus what is obviously exaggerated. An example of this is a friend of mine was at my home watching Hamilton. She is a professional opera singer and had memorized the film. She was astounded at the level of detail she heard in the orchestration in my home theater that had escaped her in other venues. She now plans to fly to my home to rehearse any new operas she performs if she can get her hands on a good recording. Highly resolving and reasonably accurate sound reproduction is unfortunately uncommon.

[@TheNaboen]

This was brilliant!

[@AudioScienceReview]

Ah, you are very kind.

[@SpinnerPaddlefoot]

Thank you Amir for your this basic detailed explanation. Would it be possible in the future to provide a deep dive into the equalization that you mention to assist in correcting errors, describing the hardware and/ or software options that are available, as well as the location within the audio chain where they should be applied?

[@AudioScienceReview]

My pleasure. Yes, it is on my Todo list. The challenge is how to convey the audible difference EQ is making through a video. But yes, I need to do it so will find a way. :)

[@SpinnerPaddlefoot]

@@AudioScienceReview Thank you again. You are invaluable to all who love audio.

[@EndstyleGG]

Wow, apparantly I figured that ERB thing out before by accident, when I was doing exactly what you said about taking a random filter and applying it over different frequencies. I noticed I couldn't really hear a difference at higher frequencies and it makes so much sense now!

[@AudioScienceReview]

Great to see that you figured it out intuitively. I am so surprised that many people keep putting these little filters in there and not realizing their (lack of) effect.

[@muziekkamer]

WoWWWWW Amir when you talk you also say something! If you tell me something I learn something too, When you're done talking I'm smarter than before. If you're going to wear that blue-red suit with that cape and you put a letter A on your chest.. no one will ever look at Superman again. you are the only human on earth that i will pay to be friends with. very helpful this video when you are in the process of getting your speakers in place.

[@raghavamohanm]

Thanks for great video ! I was thinking applying AutoEQ convolution filter was best for my headphones. Do you then suggest to only use Parameter EQ with 5 bands that is also generated there ?

[@antoniomarsicola8608]

Thank you a lot Amir! Would you suggest then to apply "psychoacoustic smoothing" to the graphs?

[@peaksingularity3032]

Yeah, I kept waiting for him to show them to us... but he didn't - why ??

[@davidmurton3174]

This is another great article Amir, thanks. A question; since we have an ERB function, would it not make more sense to display the SPL, instead of on a logarithmic scale, on the ERB scale. We could then filter based on the bucket size and end up with a graph which represents the "average human" perceived response of the speaker. Has this been done? Would it make any sense?

[@AudioScienceReview]

The ERB impacts the frequency axis, not the SPL one. If you filter the X axis, then it will do what you want in the way it will average the energy across multiple frequency bands.

[@davidmurton3174]

@@AudioScienceReview Thanks very much for your reply... It was what I meant actually although I obviously wasn't very clear :(. Is there a mechanism (in REW for example) to integrate this filtering on the frequency axis? I'm about to start measuring a couple of loudspeakers for my own amusement :)

[@michaeltuohy1249]

Fantastic video! I always wondered why I struggled to hear EQ changes at different frequencies. I thought my hearing was just getting worse. Now I know! ERB! I think I'll use the "ERB factor" when my wife accuses me of not listening to her. "But honey! ERB is preventing me from differentiating your higher pitched voice from other background noise" Think it will work?

[@drumphil00]

I say give it a go, and get back to us :)

[@awl649]

He haven't got back to us, may you rest in peace Michael 😂

[@michaeltuohy1249]

😂😂😂

[@timwillson9284]

Excellent info. I remember the EQ craze in the late 70's and early 80's and the frustration customers had trying to improve the frequency response of their systems. Graphic EQ's were too blunt an instrument with the specific selected frequencies not necessarily in the correct range,due to what you just explained about broad range. There were quality Parmetric Equalizers from SAE , Soundcraftsmen and others but few really understood how to use them at the time or realized the changes would be subtle if properly implemented.

[@AudioScienceReview]

Thanks Tim. Indeed, a ton of damage has been done to reputation of EQ because of those horrible graphical EQs. Many also added a ton of noise/hiss which made matters worse. Today, I don't know how you get great sound without EQ.

[@dasneueprogram]

Hi Amir, love your stuff. Would appreciate a video explaining room modes, as you mentioned in this video. Thanks!

[@deadline7610]

Nicely done and perfect timing. Newbie question - As I'm looking to tweak things with my Sundara's I read in one of your charts "you need more current than voltage to drive the Sundara's" is that amps ? As someone who never listens at high volume what is considered more current and what is overkill (what am I looking for on the specs of my dac/amp) ? thanks in advance

[@ronniefranks4351]

Excellent presentation. With so much talk on smoothing and psychoacoustics, could you please comment on using the psychoacoustic smoothing filter in REW? Instead of guessing what may or may not be audible, doesn’t this filter automatically display what you’re actually hearing without guessing?

[@kingofthecrate]

Thank you for this Amir, this has helped me understand much more now and my nerd meter is pegging pretty hard

[@puresound1856]

What an excellent tutorial ! Great job!

[@AudioScienceReview]

Thanks for watching and commenting. I got lucky that some of the material was already there in my articles and such so it didn't take a ton of effort to put together.

[@danielgeiger7739]

Thanks for this. What I don't understand is why is 1/3 octave too low resolution at low frequency? If at 20 Hz the bandwidth = 20 Hz, that is a full octave. So 1/3 octave = ~ 7 Hz would be 3x oversampled. Intuitively the widening of the auditory bands makes sense, as the musical scale is an geometric function. However, the low frequency explanation does not make sense to me. Sorry! If you can clarify that, I would very much appreciate it. I also find it fascinating that perception of volume levels is very coarse, while tone recognition is very tight. I hear to about 3-4 cents whether note is in/out-of tune, so that is about 1/200 of an octave.

[@lucassouzaferreira]

Amir, it seems from your talk that our hearing system's bandwidth is reasonably well known and you even touched on the possibility of an adaptive filter that would average wider and wider ranges as it moves along the frequency curve. This would be a great way of comparing the FRs of different speakers. What are the challenges in implementing this?

[@goons7ersakass866]

Thank you VERY much indeed! More of those! A question: Knowing the formula to calculate the ERB isn‘t there a way to clean up the measured frequence responce applying the ERB to the graph? Greetings from Germany

[@AudioScienceReview]

Yes. A variable filter can be applied to the graph. REW measurement program has such a filter but I confess I still do it manually based on what I need to do . Room measurements impact different range of frequencies differently so it is rare that I want the entire graph to be correct. For bass correction for example, I leave it very low filtered. Then when I want to analyze the overall tonality across the full range, then I heavily increase filtering for the entire graph.

[@freddyvejen743]

The smoothening filter width should be proportionate to the ERB range, instead of having 1/3 octave wide smoothening over the entire frequency range? I guess the calculation is doable, but will the program vendors make it? Amir, which program(s) do you use for signal analysis and creating graphs?

[@StewartMarkley]

Amir, do you have information on the ERB vs. frequency from 20Hz to 20kHz? If so I would think that an algorithm could be made to produce a frequency response graph that shows the perceived frequency response vs. the measured frequency response.

[@AudioScienceReview]

Sure. The formula is in this wiki page as I showed in the video: en.wikipedia.org/wiki/Equivalent_rectangular_bandwidth

[@StewartMarkley]

@Douglas Blake Great. Thanks. I'm finally getting my speakers finished and am armed with UMIK mic and REW but haven't used it yet.

[@StewartMarkley]

@Douglas Blake An excellent suggestion. I fully agree, I realize that much can be done with speaker and listener locations. Unfortunately I have to live with a room that is almost a 10-foot cube that doubles as my electronics lab so I will be doing some serious peak attenuations up to 200-300Hz and listening in the nearfield and messing around with my chair and speaker locations. Gene at Audioholics just finished an excellent 3 part series of videos with Anthony Grimani who is a very experienced and excellent acoustic engineer that has primed me for doing some starting locations for myself and my speakers to get the best sound via positional EQ. If you haven't watched those videos I suggest you do. Very good material there.

[@bbfoto7248]

Great topic!

[@hdibart]

Thanks,I appreciate your work.

[@thatchinaboi1]

BTW Equal Loudness Contour was the FIRST THING we were taught in Audio Engineering School and for good reason. (I am a graduate of SAE NYC Class of 2004.)

[@Miguel8131981]

Amir thanks for all the useful information. I just purchased the Elac Debut Reference DBR62 speakers from Crutchfield. I was looking for a more neutral speaker for my next speaker. Hope it can fit the bill.

[@AudioScienceReview]

Hi Miguel. My pleasure and I think you will be happy with the Elac. Many have bought it and expressed the same.

[@shaunvickers9255]

Thank you so much for that great explainer on how to relate frequency response to our hearing filters. This really helps me understand what has an audible impact and what does not in frequency response. In a future video, could you relate subjective musical sounds to the frequency response curve so I could make a visual map of what frequency response levels affect which parts of the "music sound spectrum." E.G. "From 2khz-4khz provide musical information about echos and spatial sounds that generate the recorded room or hall acoustic signature, and 20hz-30hz provide information on the XX instruments and reverberations creating physical effects felt by your body..."

[@MAudiophile]

Hello Amir. So, would the ERB smoothing be the best option in REW for measuring speakers frequency response (average room response) for a review? I wanted to use var smoothing according to other guide I've watched earlier but now I am not so sure - still a newbie in this. I'd be grateful for clarifying.

[@Nightjar726]

Amir, how can we implement room correction in between our source and DAC? What products are good for this? I’ve seen some stuff from Dirac but not sure how it works. Lots of us stream tidal or Qobuz. Is there something that we can use to smooth some of the low freq response at least ? Thanks !

[@jaaptube9]

Very interesting. I'm using Dirac on MiniDSP SHD Studio for 2 years now and every few months I'm changing target curves. Bud I did not know about looking at the curve differently between highs and lows. This is very helpfull. Still I would be very interested in a lesson :-) on adapting Dirac (or other) target curves.

[@cha7260]

Nice vid. I agree with eq filters, that less is better. Especially filters that boost. I've noticed distortion when boosting so I mainly try to attenuate.

[@AudioScienceReview]

Indeed distortion is the enemy of boosting. This is why I also perform distortion testing and am always careful of boosting in those regions above bass. In bass area, the perceptual effect of proper bass is very important and audibility of distortion rather poor. So it works better there but all else being equal, you want a transducer with low distortion to allow boosting as necessary to fix tonality.

[@timealchemist7508]

Thank you for helping to explain this topic. Would you mind creating some videos on the tuning of these zones? It seems like some rules of thumb (This Q for this range) would be helpful... or at least explaining why it’s not helpful would be... helpful? Thanks again!

[@HyviaVideoitaMansenlale]

So what you are saying is the horizontal scale should be even more "extreme". Thx

[@duroxkilo]

the convoluted shape of the pinna (outer ear shape) influences the perceived sound in ways an audio cable is never be able to (or an amp for that matter). pun on a pair of over the ear phones, play a high fq sine tone and slightly reposition / move the headphones over one ear. you'll be able to attenuate the sound to such a degree that you might think you're having a defective headphone cable..

[@omershibolet8602]

Thx very much, this was eye opening. One question though - as in FR graphs the X axis is logarithmic, the graphs are already displayed in an ERB-similar manner. I.e., a certain dip at 100hz is roughly 1/10 the size, in hz, than a same drawn dip at 1000hz, as the X axis is much condensed at higher frequencies. So two visually similar dips should have same ERB effect?

[@AudioScienceReview]

The scaling only impacts how the graph is presented, i.e. stretched or compressed. It does nothing to integrate the range of frequencies to represent them as one value. In other words, we are interested in the amplitude be correctly displayed relative to what frequency we are interested in. If you take the one graph I had with thousands of spikes, you can stretch or compress it and you still won't get the smoothed graph that I showed.

[@omershibolet8602]

@@AudioScienceReview Thx for reply :) What I meant, was exactly about the presentation of the graph - that if we inspect dips visually, take two visually similar dips, then the lower freq one will already "include" less frequencies, similarly to the ERB dependence on frequency. I.e. similar dips on the graph will have similar auditory effect? Thx again for raising the psycho-acoustics factor, this is extremely missing in all audio discussions.

[@thatchinaboi1]

Listen to a pair of speakers or headphones at 85 dB SPL and then listen it them at 93 dB SPL and you will clearly hear the effect of Equal Loudness Contour. Suddenly the same set of speakers or headphones that sounded flat is now harsh. The frequency response didn't change. Our perception of it changed due to the increase in SPL.

[@nmnate]

Always been curious about this...how do we get to things like imaging and stage width / height from a quantifiable measurement?

[@branislavokon5009]

Hi, Amir, great video! In your speaker reviews, you assess the effect of the applied EQ only by listening. Have you ever tried to repeat the Klippel measurement with EQ? I'm not sure if it's technically possible (I know you use Roon EQ so you'd have to insert another parametric EQ device into the signal path - if the Klippel system allows it).

[@AudioScienceReview]

I have been asked to do that. The Klippel has no direct method to use a parametric EQ. You can give it a response filter but you have to generate that and I am too lazy to do so. :) In general, the EQ will do what you expect any way. If you boost 100 Hz, then that is what the measurements will show. SO I am not seeing the usefulness of it relative to the work it takes to get it done.

[@jozefserf2024]

Thanks for shining a needed light into the darkness.

[@MrAnddre]

Amir, Talking about psychoacoustic, what is your take on applying an average hearing curve, with all its known characteristics per frequency range, as a kind of an eq base line instead of the flat, or almost flat line you showed? If that makes sense, do you think that computational wise we already have the standard market hardware or it would cause other problems and we better stay with the "already known devils"? Best Regards,

[@AudioScienceReview]

If I am understanding your question right, you don't want to do that because whoever created music has similar hearing system so the non-linearities are built into the content you play. If a computer was creating the music automatically, then yes, you would want to follow such scheme. There are systems with loudness control that are volume dependent to compensate for varying sensitivity to bass with volume for example. They are a good option to have although I would want an adjustment coefficient as we are not all identical in our hearing sensitivity that way.

[@MrAnddre]

@@AudioScienceReview Thanks, Amir. I didn't take into account the sound engineer hearing system during the mix. On the other hand, when analyzing our room response where we have the calibrated mic file, does this file already have our "hearing system integrated into its callibration"? Best Regards

[@Antoon55]

Great stuff, thanks for sharing!

[@AudioScienceReview]

Thanks for watching Ton.

[@crispindry]

Excellent, you've taught us so much. Thanks.

[@Sinthora97]

Is it true that ERB does not concern the human hearings ability to differentiate between levels of loudness? Let's say i had two clean sinus tones one at 10kHz and one at 100Hz. Now we make both tones x dB louder oder softer. I assume i would hear the db change in both tones with the same intensity because ERB is about differentiation in pitch not level. Am i wrong?

[@BoredSilly666]

Hi Amir, I love my sound and Hifi and Im also Autistic. My hearing seems to be pretty sensitive. Is there any way of telling if I can hear in a different way to other people? Thanks

[@AudioScienceReview]

Maybe. Try to encode some music to MP3 at say, 256 kbps. Then use a program like foobar with its abx plug-in and see how easily you can tell it, and the original source apart. This should be extremely difficult to impossible. If it is easier, then you are way ahead of general public! For a test of frequency response, get a copy of Harman How to Listen software. See how high a level you can climb up to: seanolive.blogspot.com/2009/05/harmans-how-to-listen-new-listener.html#:~:text=May%2030%2C%202009-,Harman's%20%22How%20to%20Listen%22%20%2D%20A%20New%20Computer%2Dbased,professional%20and%20automotive%20audio%20products.

[@drewwilson1477]

Amir. Excellent. Could you please recommend one or two good reference books on psychoacoustics for those who would like to learn more on the subject. Also the discussion on width of the deviation. The graph is logarithmic and as such visually it accentuates width as a functional frequency. Would it not be better to adopt a horizontal scale based on ERB? Always enjoy your going back to school episodes.

[@AudioScienceReview]

Sure but unfortunately they cover the topic from A to Z and don't try to relate them to what audiophiles care about. The bible here by far is the Fastl and Zwuiker Text, "Psychoacoustics: Facts and Models". It is available electronically on Amazon: www.amazon.com/dp/B000V1M90M/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1. I highly recommend getting electronic versions so you can quickly search for what you want. It is much harder to do that with the physical copy. On your question, yes, you could apply the filtering horizontally. REW program has such a feature but as I just explained to another person, it is rare that I want to look at the full spectrum at once. I separate bass from the rest and for the former, don't filter much, and for the latter, I filter a lot as I showed in the video. Maybe I am too much old school that way :).

[@nikosidis]

Thanks a lot Amir. Very useful info.

[@AudioScienceReview]

My pleasure. Thanks for watching.

[@christakimoto8425]

One question, we all know with age that there is highi frequency hearing loss. But with age, does the width of the ERB change as well? In other words, as you age, do you start to average larger bands of frequency together? Thanks in advance!

[@markfischer3626]

If high fidelity is convincing recreation of sound heard live from a recording then there are engineering criteria that must be taken into account in the playback system. The first arriving sound must have a flat frequency response all the way back to the recording microphones. Wide uniform dispersion particularly at high frequencies is critical. The beaming directional tweeters universally used today are awful. Then there are the reflections that must be engineered to recreate the reflections of live music. There are two kinds of problems, the reflections that would be heard were the musicians in your room and the reflections that would be heard at a concert venue. In the first case that is much of what you hear, in the second case that is almost everything you hear. Not only are spectral changes of reflections compared to the first arriving sound critical but so are the time delay, direction of arrival, and loudness compared to the first arriving sound. These must be engineered in a way to take into account the variables of the acoustics of the listening room and the variables in the way the recording was made and the kind of environment the type of music is best suited for. Since you can't hear the direction of even one reflection, understanding how the brain determines direction is critical if you are going to defeat it in an engineered sound field. So you have to learn how to model, analyze, and engineer sound fields. The currently accepted explanation of detection of direction is dead wrong. This is proven by binaural recordings played through headphones. It meets all of the believed theoretical criteria but fails anyway so it's wrong. So while frequency response is critical and necessary it is not sufficient. The current technology fails miserably and compared to live music. Recordings played through it sound dead, flat, boring compared the real thing. IMO the work product of this industry is a total failure. Did I solve this problem? Yes, nearly 50 years ago. I admit it's a tough problem, beyond the ability of the people I've met or listened to what they've had to say. I've solved tougher problems but this one isn't nearly as simple as they would have you believe. How can you solve a problem you don't even understand?

[@mysock351C]

Question: Regarding frequency response, is there any transition region between the far field and near field when using speakers? E.g. is there a point where the preferred frequency response is no longer flat? I found that with a near field system the response that gives the best overall neutrality as far as acoustics goes actually looks a lot like the Harman headphone curve with a similar peaking where the ear is most sensitive. The same setup when used in the traditional far field had, as one would expect, a flat response (or at least as flat as could be measured in-room).

[@AudioScienceReview]

The transition is frequency dependent unfortunately. So one number doesn't get you there. My Klippel speaker measurement system can compute this but I don't know how to present such data. Note that this applies to the technical definition of near/far field. It may not necessarily be what you mean (driver integration?). That value is not easy to compute.

[@mysock351C]

@@AudioScienceReview FWIW Im using large tower speakers and a subwoofer as speakers for my PC. I sit about 3' in front of the speakers (they're about 6' apart) and my listening position is about 70° off-axis. In filter terms, the peaking in the response ended up being centered on 6kHz for best results, with a Q of 1.7. The response peak is quite well defined in the measured frequency response profile (not the EQ itself), and necessary as without it the sound is very unnatural. With the EQ in place, ambient sounds in videos (e.g. birds chirping, conversation, etc.) sound as they do in real life. The fact that its at 6kHz and not 3kHz may be due to my hearing, which seems to skew towards the HF end. I'm over 40, but can still hear to almost 20kHz.

[@Nightjar726]

Thank you so much! Very informative. No measurements or experience with ProAc Speakers? I have a pair of DT8’s and they measure pretty well in REW in room. Very very curious to someday soon try a pair of Revel PerformaBE to see what all the hype is about in very well measured speakers. Thank you once more Amir!

[@AudioScienceReview]

Thanks for watching. No, I don't have any experience with ProAc speakers. Hopefully one will be loaned for testing.

[@Nightjar726]

@@AudioScienceReview I would send you mine but I have no backup to listen to. Ha. Plus it must be pretty expensive. Thanks for taking the time to post these super informative videos. I am trying to do now for audio what I did for guitar after over 35 years of playing. Learn as much as you can about your current gear. Play and experiment with setup , measurements , knowledge etc. this way I will learn more about how everything works, know more of what I like and what I want and when I get anything I will know how to optimize every inch I can to squeeze out of it.

[@bobe2933]

AUDIO GEAR SHILLS HEADS ARE BOILING, WITH EVERY VIDEO YOU RELEASE :D

[@audible67]

Not really.

[@bobe2933]

@@audible67 7 people seem to agree with me.

[@audible67]

@@bobe2933 7 bitter idiots and an unknown number of people who know better.

[@bobe2933]

@@audible67 you sound bitter

[@audible67]

@@bobe2933 hahaha says the guy who wrote "AUDIO GEAR SHILLS HEADS ARE BOILING, WITH EVERY VIDEO YOU RELEASE :D" about a video that he did not watch, can't understand and really does nothing to back up the random troll. good job, dummy.

[@Gabriel-of-YouTube]

Very useful, thank you!

[@AudioScienceReview]

Glad you found it useful Gabriel. Gives me motivation to do more.

[@Gabriel-of-YouTube]

@@AudioScienceReview I really appreciate you!

[@HoundStuff]

Very nicely explained, thank you!

[@sudd3660]

you forgot to think about one thing here, 3khz bank bandwith for example, dont mean its a smoothing filter in every case. it only filters when multiple sound are present there. a pluck of a string at 15khz still keep its volume, its when you add many other things in the same bandwidth it gets averaged out.

[@foblivio]

Excellent! Learned something new!

[@tomas_m]

I was hoping this would contain explanation of what headphones measurements imply what sound aspects. Qualities like detail, bass impact, airiness, veil/transparency, soundstage/imaging...

[@AudioScienceReview]

That is a vertical treatment of a horizontal topic I presented in this video. I will put it on my Todo list although I will say that the science there is not near as settled as one would want. I will however share my own experience and tentative conclusions.

[@siriosstar4789]

Enjoy what you like and never doubt that you like it l

[@clementc7297]

Thank you very much! Great lecture

[@richardherbert3519]

Great video! !

[@skip1835]

Excellent video - thanks Amir - I don't know if you've ever covered this, but I wonder how filtering affects phase response (which I don't fully understand) and how that phasing effects the overall sound that I hear - I have messed with a room correction tool - I'm not sure if it was the phase thing that bugged me or not, but something about it made it not worth keeping it permanently in my system - because of that experience, I've avoided electronic eq correction since.

[@AudioScienceReview]

Hi Skip. I plan to do a video on phase. For now, the simple answer is that it doesn't matter especially with speakers. Any sound you hear is a combination of direction sound and reflections from many surfaces with different phase. But then time you perceive anything, you have basically random phase. Controlled listening tests have shown the same. Even with headphones, audibility is limited to special test signals. With music, it again becomes inaudible. So I would not worry about it.

[@jrcat2258]

So if you can correct all speakers this way, why do some speakers sound better than others? Is there even a point in buying any kind of expensive gear?

[@zyghom]

good morning!!!

[@AudioScienceReview]

Good morning back to you! :)

[@kevinkrych4233]

Thank you! The curtain is being pulled back for me....

[@InsideOfMyOwnMind]

Should be required viewing to get an audiophile's licence.

[@AudioScienceReview]

:)

[@LtColDavenport]

What is a good parametric EQ for windows not tied to a streaming service or player?

[@AudioScienceReview]

Unfortunately I only use the Roon player so don't have personal experience with other methods. The most common one I hear is the Equalizer APO. One member was kind enough to make a compete list of all that is available: www.audiosciencereview.com/forum/index.php?threads/eq-software-for-windows-linux-macos-ios-ipados-and-android.18450/

[@LtColDavenport]

@@AudioScienceReview Thank you a lot Amir. Really kind.

[@LtColDavenport]

@Douglas Blake Would you suggest me some tutorials on how to use it if that's the case? Thanks.

[@LtColDavenport]

@Douglas Blake Thank you again for your time!

[@_han.soso_]

thank you for the public service! :D

[@rlwings]

Room correction algorithms can use thousands of filters and sound excellent.

[@JohSno]

Thank you.

[@AudioScienceReview]

You are welcome. Thanks for watching.

[@chengong388]

So basically the ear can only hear limited "colors" rather than working like a spectrometer

[@Lesterandsons]

Thx

[@nonchalantd]

♥

[@bradt.3555]

It's sad but psychoacoustics is used to sell SOOO much hi end audio stuff. And to argue with some people that something can't do what it's said to do and they may be hearing placebo effect WOW! like you just called their mother dirty names. My latest argument with some people was about "audiophile" wall outlets! Yup, the recepticle in the wall, Oh, the bass got better more defined, better detail in the mids, on & on. I ask how and get told just listen for yourself. Pure nonsense.