Understanding Audio Frequency Response & Psychoacoustics (Video)

[amirm]

For some of you this is old news but for many, I thought it would be good to do a tutorial on frequency response. No, not the trivial aspects of it but digging into psychoacoustics so that you can properly analyze headphone, speaker and room measurements and determine audibility of deviations from neutral.

Article Referenced:
Perceptual Effects of Room Reflections: https://www.audiosciencereview.com/...ds/perceptual-effects-of-room-reflections.13/

 

[mcb]

I have really enjoyed all of your "back to school" videos. I always learn something new.

Does it make sense to scale the frequency response by the inverse of the ERB before smoothing and then undo the scaling? This would attempt to smooth more where the ear is less able discriminate adjacent frequencies and less at the more critical lower frequencies.

 

[dtaylo1066]

Great video. Many thanks. Most informative. How does one's individual hearing with it's potential quirks, anomolies, age, etc. affect things. At age 64 my hearing has some degradation, particularly in upper frequences. In a hearing test I am good to maybe 12K, but that would be down in dB compared to my ability to hear lower frequencies. So if one EQs a speaker to be closer to a flat or an optimal response curve, but one's hearing is not flat, what would be the result? I would also wonder what the size and position of one's ears compared to another person would have on their hearing and perception of audio. Example: If one physically adjusts one's ears slighly to a more forward facing position, the difference in sound is immedialtey apparant, and it seems that it is not just in dB level, but also in terms of spacial or stereophonic qualities.

 

[MasterMech]

Wealth of information here as always, many thanks again for sharing your knowledge.

 

[DerRoland]

Hi Amir, love your "teaching" lessons every time.

Some thoughts:
- FQ charts are logarithmic, so on left side the steps are 10 Hz, right 1000 Hz, our different hearing possibilities should be correct represent?
- do you advice the filtering type "variable" in REW for best averaging a measurement?
- general, recommending to use (parametic) filters, why nobody say a word about the drawback of shifting the audiophase (=groupdelay), especially when using separated activated chassis with a digital crossover (e.g. DCX or 360venu) and twisting the phase with filters?

 

[roog]

Hi @amirm, thanks for your video, I learn something from each one. Can I ask, what do you use to implement parametric EQ in an audio system, please?

I have seen products such as NAD and Mini DSP have bespoke firmware solutions, but is there an easy way to add it to a generic music streaming system?

 

[Vini darko]

Thanks Amir good video.
I have a question about the way the frequency graph is laid out. Why do the box sizes vary like they do? They start wide , go narrow then wide then narrow ect. It doesn't seem to correlate with any aspect of pshcoacoustics that I've heard discussed.

 

[ernestcarl]

Even if one knows a narrow half dB here and there in the higher frequencies doesn’t matter as much or at all, audiophile nervosa demons must be appeased — lest the stress of an imperfect graph impinges over on one’s consciousness on and off without hope of respite — it is an almost incurable ailment.

 

[paolomo]

Great video. Amir mentions a couple of things towards the end, which hit the nail on the head. 1) Narrow PEQ filters have often inaudible effects. 2) The way different softwares handle the tails of PEQ filters is not necessarily represented by the pretty curves they show. I see some people fighting wars over their favorite EQ presets. I say, go ahead and pick up a super detailed preset if that is your thing, but also have fun turning individual filters on and off, to see what they actually do -- and to what extent.

 

[ernestcarl]

Thanks Amir good video.
I have a question about the way the frequency graph is laid out. Why do the box sizes vary like they do? They start wide , go narrow then wide then narrow ect. It doesn't seem to correlate with any aspect of pshcoacoustics that I've heard discussed.
View attachment 125609

The scaling is already logarithmic to reflect more our human hearing so maybe the vertical lines spacing standard so commonly on display in these graphs are just there to make it easier to read and separate frequency bands? Not entirely sure...

 

[diddley]

For me as somebody with absolutly no knowledge, these video's are a really great way of learning.
It makes enourmous difference if you see and hear at the same time for understanding what Amir is saying (or at least try to understand)
Thanks for sharing your knowledge Amir and do it via this route.

 

[sutantoroy]

Thanks Amir good video.
I have a question about the way the frequency graph is laid out. Why do the box sizes vary like they do? They start wide , go narrow then wide then narrow ect. It doesn't seem to correlate with any aspect of pshcoacoustics that I've heard discussed.
View attachment 125609

Its the weighting between the frequency octave behaving logarithmic.

 

[Docevil]

Great video Amir, really enjoying the topics you have been putting up!

 

[phoenixsong]

Hi Amir,

Thanks for the informative tutorial How audible will resonances be in the upper region of the frequency response, considering there is a strong filtering effect on dips and peaks in that region? Does it work in the same way for that or is it actually something different?

*Edit: LOL I just realised it may simply depend on the width of the resonance itself- resonances are the Z axis built on the XY axis after all. Maybe I should rephrase the question to query about the relation of the amplitude and duration of the resonance with its width and filtering effects instead

 

[Ismapics]

Hello @amirm thanks for the knowledge content. I have heard so many of the so called YouTube Adjective reviewers making the claim that although they are entering into an age where they loose spectrum to Presbycusis, that Psychoacoustics is what fills in the blanks. Also they use the word Psychoacoustics when describing the effect of stupid tweaks like cable raisers and expensive tinker-bell cables.

My question is would the reason humans "compress" in the higher frequencies an effect of evolution. Did we evolve to that way in order to assure survival, or even be more tuned to Catch prey. Interesting why we would hear more frequencies at the Lowe end could it be because we feel those as well as we hear them?

Any additional reading is welcomed. Cheers.

 

[Ismapics]

Hi @amirm, thanks for your video, I learn something from each one. Can I ask, what do you use to implement parametric EQ in an audio system, please?

I have seen products such as NAD and Mini DSP have bespoke firmware solutions, but is there an easy way to add it to a generic music streaming system?

If I am not mistaken he is showing a Roon parametric eq screenshot.

 

[Docevil]

Thanks Amir good video.
I have a question about the way the frequency graph is laid out. Why do the box sizes vary like they do? They start wide , go narrow then wide then narrow ect. It doesn't seem to correlate with any aspect of pshcoacoustics that I've heard discussed.
View attachment 125609

Hey Vini darko, the graph is logarithmic. Here's a link that should help explain it:
https://en.wikipedia.org/wiki/Logarithmic_scale

Edit: I should say it's semi logarithmic ie logarithmic only on one axis

 

[AdamG]

Give a Man a Fish and feed him for a day. Teach him to fish…… @amirm, these ASR virtual Classroom teaching moments are Solid Gold. Thank you for taking the time you do to do stuff like this for our ASR Community.

 

[prerich]

For some of you this is old news but for many, I thought it would be good to do a tutorial on frequency response. No, not the trivial aspects of it but digging into psychoacoustics so that you can properly analyze headphone, speaker and room measurements and determine audibility of deviations from neutral.

Article Referenced:
Perceptual Effects of Room Reflections: https://www.audiosciencereview.com/...ds/perceptual-effects-of-room-reflections.13/

This was very good!!! Takes me back to my Navy CT days!

 

[Ajax]

Hey Amir,

I've been buying & enjoying good quality HiFi equipment for 40 years, and my friends and family see me as a guru. However, my knowledge base has been greatly increased thanks to your videos explaining the intricacies and reasons behind your measurements.

Keep up the good work, your providing an invaluable service educating while at the same time knocking down the myths and BS that is destroying our hobby.