Psychoacoustics

[stereoman]

...is the gist of it all. Most expensive systems, cheap system, medium budget systems are nothing without proper room correction by psychoacoustics.

https://www.vicoustic.com/de/page/acoustic-principles

 

[nopiano]

Isn’t it just plain acoustics? I though psychoacoustics were about how we perceive sound, in our brains.

I think you’re saying that room can have a big impact on what we hear. I’m sure that’s the case, but having owned Hi-Fi systems for over forty years, and installed dozens of customers systems in my twenties, I think most domestic rooms can be quite satisfactory with careful placement and set up.

 

[Vladimir]

Research McGill University, Harman and JBL have done showed people want to hear the room. Our brain hears a room and then EQs the sound to solve issues. If you then introduce anechoic conditions to it (like headphones) it will scream WTH HAPPENED!? They will sound just wrong, and most headphones can't compare to speakers for this exact reason. Yes, you can appreciate details in the sound in a more analytical manner with quality headphones. But it feels as natural as using a microscope instead of glasses to read a book.

Ironically headphones are praised for taking the room out of the equation. Psychoacoustic and acoustic engineers are strugling to bring back the room into headphones somehow and replicate the speakers-in-a-room experience. Studios have a live and dead end in their recording rooms for a reason. Mixing and mastering is done primarily or at least checked on speaker monitors, not headphones. Open headphones try to simulate a sound stage because listening the musicians in the middle of your head sounds unnatural. Next step is making headphones that follow the Harman target curve, which is a slightly bassy slope in the FR.

So basically speakers need to be made flat in anechoic chambers and played in a normal room. Headphones need to be made to sound like flat speakers in a normal room because listening to speakers in anechoic chambers is not nice.

 

[Vladimir]

Floyd Toole - Sound reproduction – art and science/opinions and facts

Tyll Hertsens - Finding Flat: How to Interpret Headphone Measurements

 

[insider9]

Big distinction between the two, sure they're interlinked. But you can have a good psychoacoustics performance from less than ideal acoustic venues. Yet, whenever possible and viable, it's always great to improve acoustic performance of the room. In general it will also bring psychoacoustic gaints. What's the difference? Rather substantial in my opinion. Am I being petty? I don't think so, it's something that interests me greatly.

While acoustic room treatment will improve psychoacoustic performance to a good degree, from acoustics point of view this improvement is really secondary. Why? Because while good treatment will improve every aspect of performance from acoustics perspective, it simply cannot achieve that in relation to psychoacoustics. As much as DSP cannot fix your room, as much you can't do some things from psychoacoustics perspective with room treatment. You'll need to use electronics for that most of the time.

Psychoacoustics deals with perception of sound that varies according to number and location of sound sources, venue, noise, distortion, frequency, volume and more. Psychoacoustic principles can be used in a wonderful way to improve stereo playback involvement by use of software e.g. crossfeed (both headphone and speakers). Bur there's so much more to it.

As an example consider a busy train station and its PA system. Large highly reverberant room, high background noise, multiple sources of sound, yet properly done announcement are easy to understand. How is it that many hifi systems can make vocals often not as clear in a quiet room as PA system in an train station or an airport? Exaggaration? Sure, but you get the point. An example where acoustic performance might be quite poor but smart use of psychoacoustics makes the result worthwhile. If this interestest you read about speech intelligibility or specifically STI (Speech Transmission Index).

Alternatively for those who would like to give it a go and fancy measuring it with REW. Sadly REW doesn't show STI. But Clarity graphs are near equivalent C50 (for speech), D50 (for definition). I believe ARTA could measure STI (but it's not free).

 

[Vladimir]

Wrong speakers in the right room or Right speakers in the wrong room. Pick your poison.

 

[insider9]

Wrong speakers in the right room if that's the choice.

Given how easy it is to replace speakers and how hard it is to change the room. Not to mention there's always DSP, which can improve speakers but not the room.

 

[Al ears]

Wrong speakers in the right room or Right speakers in the wrong room. Pick your poison.

Headphones?

 

[Vladimir]

I'd go for the right speakers in the wrong room. I get used to the room quickly and it doesn't bother me too much.

I'm not shy to use the tone controls for boomy sounding material.

 

[insider9]

Most do, Vlad. But that's often a sing their room isn't too bad. Tone controls as well as DSP don't remove boom just hide bass.

Reflections colour the sound in an unpredicatble way. It depends on what frequencies are reflected and what are absorbed or scattered.

Even in a room that's not bad a ceiling can reflect 30-40% of direct sound. That can often translate to 10dB under what your speakers are playing. That's like playing additional pair of speakers which are not just delayed to the main ones but playing at half the volume. Half the volume and with a different frequency response too. Even with best speakers you can see that's not right. And that's just one surface.

Signs your room is an acoustic nightmare:

- you can't listen loud as it just gets uncomfortable; it feels like noise and not music anymore at higher volumes (signs of high reverberation)

- bass booms, lacks definition and doesn't feel controlled (high bass reverberation)

- you can't get a good stereo image (signs of many early reflections)

- every description of your gear just doesn't correlate with your experience (speakers that sound too bright or too rich where they not supposed to) (sings of uneven reverberation and/or big reflections)

 

[Vladimir]

- you can't listen loud as it just gets uncomfortable; it feels like noise and not music anymore at higher volumes (signs of high reverberation)

Check.

- bass booms, lacks definition and doesn't feel controlled (high bass reverberation)

Check.

But if I don't play them too loud it sounds FANTASTIC. I think the meaty bass sounds good at low and normal listening levels (Fletcher-Munson curve). And the reflections make acoustic music sound lively and immersive.

The 70-80Hz room mode isn't going anywhere. I tried everything. When I want really loud, I hook up the headphones and boogie.

 

[insider9]

Bass is difficult to do in any untreated and even some treated rooms. Room mode could be deal with using tuned bass traps. Personally, I wouldn't do it.

However you could look to dampen the room a little to reduce reverberation. Over 1s would be quite a lot. I aim for 0.25s but got a little lower at the minute.

I'm sure if your room acoustics would be awful you would've done something about them by now. Or just use headphones most of the time. I hope this doesn't come across as criticism as it isn't meant that way.

I encourage everyone to do something in this regard it really is the biggest upgrades one can have. Especially compared to money spent.

 

[stereoman]

It took me about one year. To understand now how lateral room reflections were killing my sound. No matter what systems and what speakers I had. It really is the issue. I am not talking about making your living room like a studio but just to find the few right spots. And those can be anything. Do not attempt to place your speakers and system symetrically just for the Design. The best sound can be from totally assymetrical speakers-to-walls positioning. Even few miliseconds of the treble lay over is making the sound unacceptable and that is not really the thing of the bad system. I got to the point where there are 4 critical things to be wary of:

1. One of the speakers in relation to the left or right wall distance.

2. Speakers internal distance from each other.

3. Avoiding symmetrical positioning in a mixed room. I.E. 2 windows on the back wall, 1 window on the right or left. This will make symmetrical positioning from right and left side wrong ! Because of the reflections ( just an example )

Speakers' size won't matter so much - what matters is the reverbaration of the high frequency sound. To find the right spot can be quite an achievement though. It takes some time. The shifting of the components even just a few centimeters in some cases.

 

[stereoman]

I’m sure that’s the case, but having owned Hi-Fi systems for over forty years, and installed dozens of customers systems in my twenties, I think most domestic rooms can be quite satisfactory with careful placement and set up.

Oh no. It's much more than this. Many ( included me ) actually the majority of people who are into Hi Fi do not realise how huge impact this makes. I am not really talking only about putting a new carpet on etc. It really is the math of the sound reflections. But once you get it right, almost not matter which system you have - it should sound really good and proper. I think and believe so.

 

[newlash09]

Research McGill University, Harman and JBL have done showed people want to hear the room. Our brain hears a room and then EQs the sound to solve issues. If you then introduce anechoic conditions to it (like headphones) it will scream WTH HAPPENED!? They will sound just wrong, and most headphones can't compare to speakers for this exact reason. Yes, you can appreciate details in the sound in a more analytical manner with quality headphones. But it feels as natural as using a microscope instead of glasses to read a book. 

Ironically headphones are praised for taking the room out of the equation. Psychoacoustic and acoustic engineers are strugling to bring back the room into headphones somehow and replicate the speakers-in-a-room experience. Studios have a live and dead end in their recording rooms for a reason. Mixing and mastering is done primarily or at least checked on speaker monitors, not headphones. Open headphones try to simulate a sound stage because listening the musicians in the middle of your head sounds unnatural. Next step is making headphones that follow the Harman target curve, which is a slightly bassy slope in the FR.

So basically speakers need to be made flat in anechoic chambers and played in a normal room. Headphones need to be made to sound like flat speakers in a normal room because listening to speakers in anechoic chambers is not nice.

 

Your opinions are always a new perspective to look through. And iam really glad you are back. Nobody can blend knowledge, substance and pure wit the way you do 😀

 

[nopiano]

I’m sure that’s the case, but having owned Hi-Fi systems for over forty years, and installed dozens of customers systems in my twenties, I think most domestic rooms can be quite satisfactory with careful placement and set up.

Oh no. It's much more than this. Many ( included me ) actually the majority of people who are into Hi Fi do not realise how huge impact this makes. I am not really talking only about putting a new carpet on etc. It really is the math of the sound reflections. But once you get it right, almost not matter which system you have - it should sound really good and proper. I think and believe so.

I’m not disagreeing at all that the room makes a difference, and sometimes a massive difference. But I don’t believe that invariably it causes such an issue as to render the equipment unsuitable for normal listening.

I have heard pianos playing in many different buildings, rooms, concert halls, churches, etc. They all sound different to each other, and some I preferred. But I was never unsure that it was a piano, and how well it was played. For me that applies to audio reproduction a5 home in a similar way.

 

[Vladimir]

It took me about one year. To understand now how lateral room reflections were killing my sound. No matter what systems and what speakers I had. It really is the issue. I am not talking about making your living room like a studio but just to find the few right spots. And those can be anything. Do not attempt to place your speakers and system symetrically just for the Design. The best sound can be from totally assymetrical speakers-to-walls positioning. Even few miliseconds of the treble lay over is making the sound unacceptable and that is not really the thing of the bad system. I got to the point where there are 4 critical things to be wary of:

Very true about symmetry and proportionate patterns. I don't have perfectly paralel walls and the speakers are not at the same distance from any wall. The reflections are the best part of my main system. In comparison, the very disciplined JBL LSR305 sound nowhere near as lively and interesting in the same room. The waveguide controlls the reflections extremely well, but for professional monitoring. I enjoy the room for casual listening.

Minor detour story coming from the graphic design world. When the Starbucks logo was being redesigned to keep it contemporary, the designer made one half of the siren illustration and just mirrored it, thus making it perfectly symmetrical.

The focus groups didn't like it very much. They felt it looked cold, unfriendly, artificial, sinister even. Interestingly, the solution to this was to create imperfections, asymmetry in the face and that made it feel much more natural and friendly to the observer. Notice the asymmetrical shadows of the nose, the mouth, the cheeks edges etc.

 

[stereoman]

It took me about one year. To understand now how lateral room reflections were killing my sound. No matter what systems and what speakers I had. It really is the issue. I am not talking about making your living room like a studio but just to find the few right spots. And those can be anything. Do not attempt to place your speakers and system symetrically just for the Design. The best sound can be from totally assymetrical speakers-to-walls positioning. Even few miliseconds of the treble lay over is making the sound unacceptable and that is not really the thing of the bad system. I got to the point where there are 4 critical things to be wary of:

Very true about symmetry and proportionate patterns. I don't have perfectly paralel walls and the speakers are not at the same distance from any wall. The reflections are the best part of my main system. In comparison, the very disciplined JBL LSR305 sound nowhere near as lively and interesting in the same room. The waveguide controlls the reflections extremely well, but for professional monitoring. I enjoy the room for casual listening.

Minor detour story coming from the graphic design world. When the Starbucks logo was being redesigned to keep it contemporary, the designer made one half of the siren illustration and just mirrored it, thus making it perfectly symmetrical.

The focus groups didn't like it very much. They felt it looked cold, unfriendly, artificial, sinister even. Interestingly, the solution to this was to create imperfections, asymmetry in the face and that made it feel much more natural and friendly to the observer. Notice the asymmetrical shadows of the nose, the mouth, the cheeks edges etc.

A wonderful example Vlad 😉. Ok , actually I would do everything to keep symetrical things in audio system but the sound simply won't allow.

 

[Seakiwi]

Shame they didn't fix the coffee!

 

[stereoman]

Shame they didn't fix the coffee!

True !

 

[nopiano]

While I generally go for a broadly symmetrical layout of speakers for visual reasons, I’d avoid being too accurate. Any peaks and troughs at your chosen distances from walls behind and to the sides are better not excited by both speakers. A small difference is surely preferable?