Near field, mid-field, far-field: how to choose

[CT Man]

I may have the opportunity to design an apartment within a 1400 square-foot rectangular shell where I can place room partitions mostly wherever I wish. I'm thinking about setting up an ideal one-person 2-channel listening room or area, which would also have a TV occupying a large field of view between the speakers. I would sit in an ultra-comfy reclining chair.

Assuming the selection of speakers well-designed for the distance to the listening position, is the choice among near, mid and far field set-ups simply a matter of individual taste? Or is one considered best in studies of listener preference, assuming appropriate acoustic treatment and DSP room correction?

It seems to me the question has to do with the ideal proportion of reflected sound to direct sound and how that impacts imaging and soundstage. I assume the impact on frequency response can be appropriately adjusted by room design and DSP.

I've always strongly preferred speakers to headphones, if that's meaningful.

 

[holbob]

If I could get away from the back wall in my lounge I would. If I had the choice like you have I would be a metre nearer to the speakers.

 

[badie]

an ideal one-person 2-channel listening room or area

"Ideal" might get pretty big.

If I could I´d like also more space behind my listening position.

 

[Yuhasz01]

The closer you listen to speakers, the more the room characteristics are reduced. Personal preference.

I use Genelec monitors in near field listening(2 meters). Genelec produces a chart for listening distancesa nd spl level guidelines.

 

[Keith_W]

OK this is going to be long, so buckle up. There are three meanings for the term "nearfield" and "farfield" so we will first define these terms so that we are clear what we are talking about.

1. Acoustic nearfield and farfield. These terms have a specific meaning in acoustics and it refers to the frequency-dependent volume oscillations the further the microphone is placed from the driver as shown below.

At some point, the oscillations stop and the volume begins to drop by 6dB/meter according to the inverse square law.

2. "Nearfield speakers". All speakers have a falling frequency response which is distance-dependent. The further away you sit, the more the downwards treble tilt. Most home speakers are designed to have an anechoically flat frequency response when measured at 1m, with the falling frequency target achieved at a listening distance of 3-4m. However, some speakers are designed for "nearfield listening" and have a built-in falling frequency response. Some others (such as Genelec speakers) allow you to adjust the treble tilt via dip switches. All speakers which have inadequate volume output for "farfield listening", e.g. all computer speakers and most small bookshelf speakers, have some kind of built-in falling frequency response.

3. Direct vs. Reverberant sound. This is what most of us mean when we talk about "nearfield" vs. "farfield". It is much better to use Toole's term "direct sound predominant" or "reflected sound predominant". A more formal way to express it is the DRR or "Direct to Reverberant Ratio". I'll explain.

If you look at the above diagram, you will see that when you are very close to the speaker, the direct sound is very loud. As you get further away, the direct sound starts to drop. On the other hand, the reverberant field is the same volume everywhere in the room. At some point, the direct sound will equal the reverberant sound - this is known as the Critical Distance. If you sit closer to the speaker than the CD, then you have more direct sound to reverberant sound.

The critical distance is influenced by:

- room dimensions. A smaller room has a shorter critical distance because reflections arrive earlier and are therefore louder.
- room treatment. Sound absorption by room treatment, furniture, etc. reduces the volume of the reverberant field and increases the critical distance.
- speaker directivity. Omnidirectional speakers throw more energy into the reverberant field as a proportion to direct, so the critical distance is shorter.
- frequency dependence. Because long wavelengths tend to be omnidirectional and short wavelengths directional (in a typical monopole speaker), the CD varies according to the frequency.

The DRR is formally defined as DRR (in dB) = 10 x log (SPLdirect/SPLreverb). Obtaining a measurement of direct SPL independent of reverb SPL is extremely difficult - see this paper for how professionals do it.

In general, very high DRR (5dB and above) are preferred for recording studios. 0dB or less is typical for concert halls. For domestic listening, the target is 0dB - 5dB, and it is heavily influenced by preference.

So TLDR: there is no right answer. It's up to your preference.

 

[TheZebraKilledDarwin]

1. Respect physics. The impact of acoustics on the sound can not be OVERstated.

2. Trust your ears.

1+2:
Put on headphones and pay attention how much details you can hear.
Then listen on any average setup in any room. You will notice that you hear, compared to headphones, NOTHING. No ambience, no reverb tails, no placement of each instrument and the "bass" nothing more than a wobbly mess. Simply a horrible sound.

But if you move closer to the speaker of the same setup, you will notice how much the sound begins to improve, and how more details you start to hear. Even at reduced levels.

And this negative impact of the room you hear increases exponentially with distance to the speaker. And vice versa.


Conclusion: your listening distance to the speaker will be the most important parameter to improve sound quality. At zero cost.


Sitting as far away from walls, also makes a huge difference and improves the sound a lot at no cost, too.
Do not forget: we no longer use CRT TVs. The reason to sit 3 or 4 m away fromt he TV is no longer valid. You can sit as close as you wish, without frying the brain with x-rays. that way also the screen fills a wider angle of the vision field. At no cost.
And you sit further away from the back wall, improving the acoustics and you have space to fill the rear wall with great sounding diffusors: book shelves.
Which will also make you feel comfortable while listening, contrary to a sterile room with hard surfaces.

 

[CT Man]

OK this is going to be long, so buckle up. There are three meanings for the term "nearfield" and "farfield" so we will first define these terms so that we are clear what we are talking about.

1. Acoustic nearfield and farfield. These terms have a specific meaning in acoustics and it refers to the frequency-dependent volume oscillations the further the microphone is placed from the driver as shown below.

View attachment 430783

At some point, the oscillations stop and the volume begins to drop by 6dB/meter according to the inverse square law.

2. "Nearfield speakers". All speakers have a falling frequency response which is distance-dependent. The further away you sit, the more the downwards treble tilt. Most home speakers are designed to have an anechoically flat frequency response when measured at 1m, with the falling frequency target achieved at a listening distance of 3-4m. However, some speakers are designed for "nearfield listening" and have a built-in falling frequency response. Some others (such as Genelec speakers) allow you to adjust the treble tilt via dip switches. All speakers which have inadequate volume output for "farfield listening", e.g. all computer speakers and most small bookshelf speakers, have some kind of built-in falling frequency response.

3. Direct vs. Reverberant sound. This is what most of us mean when we talk about "nearfield" vs. "farfield". It is much better to use Toole's term "direct sound predominant" or "reflected sound predominant". A more formal way to express it is the DRR or "Direct to Reverberant Ratio". I'll explain.

View attachment 430786

If you look at the above diagram, you will see that when you are very close to the speaker, the direct sound is very loud. As you get further away, the direct sound starts to drop. On the other hand, the reverberant field is the same volume everywhere in the room. At some point, the direct sound will equal the reverberant sound - this is known as the Critical Distance. If you sit closer to the speaker than the CD, then you have more direct sound to reverberant sound.

The critical distance is influenced by:

- room dimensions. A smaller room has a shorter critical distance because reflections arrive earlier and are therefore louder.
- room treatment. Sound absorption by room treatment, furniture, etc. reduces the volume of the reverberant field and increases the critical distance.
- speaker directivity. Omnidirectional speakers throw more energy into the reverberant field as a proportion to direct, so the critical distance is shorter.
- frequency dependence. Because long wavelengths tend to be omnidirectional and short wavelengths directional (in a typical monopole speaker), the CD varies according to the frequency.

The DRR is formally defined as DRR (in dB) = 10 x log (SPLdirect/SPLreverb). Obtaining a measurement of direct SPL independent of reverb SPL is extremely difficult - see this paper for how professionals do it.

In general, very high DRR (5dB and above) are preferred for recording studios. 0dB or less is typical for concert halls. For domestic listening, the target is 0dB - 5dB, and it is heavily influenced by preference.

So TLDR: there is no right answer. It's up to your preference.

Thanks, very informative but tricky to implement - no shortcuts. I think my preference tilts toward a studio-level high DRR but I want to retain enough sense of spaciousness for orchestral music. I think acoustic treatment not only lengthens the critical distance, but also can change which reflections dominate the room effect. Assuming one meter or more from the rear wall, where would one use acoustic treatment to maintain a somewhat wide soundstage, precise imaging and a DRR around 5dB? Is there a place for diffusion in addition to wideband absorption?

 

[Keith_W]

Thanks, very informative but tricky to implement - no shortcuts. I think my preference tilts toward a studio-level high DRR but I want to retain enough sense of spaciousness for orchestral music. I think acoustic treatment not only lengthens the critical distance, but also can change which reflections dominate the room effect. Assuming one meter or more from the rear wall, where would one use acoustic treatment to maintain a somewhat wide soundstage, precise imaging and a DRR around 5dB? Is there a place for diffusion in addition to wideband absorption?

Yes, there is a place for room treatment and diffusion. However, nobody can tell you what you need or where you should put them without seeing measurements. And FYI, as Toole points out, normal room furniture is sufficient to get the RT60 to target for most rooms.

Most people do not want a studio level high DRR. It sounds awful and getting the RT60 that low will impact speech intelligibility and destroy the pleasing ambience of music.

I would advise you to get the speakers, set them up, get a microphone, and do some measurements. Don't worry about room treatment for now - that comes later. How much direct sound predominance you like is strongly based on preference, and nobody is going to argue with you about preference.

 

[Duke]

I may have the opportunity to design an apartment within a 1400 square-foot rectangular shell where I can place room partitions mostly wherever I wish. I'm thinking about setting up an ideal one-person 2-channel listening room or area...

Imo there are worthwhile benefits to longer first-reflection path lengths, both in sound quality and spatial quality. And bass quality increases as room size increases. Of course these are not the only considerations for how to make best use of your available space,

 

[TheZebraKilledDarwin]

Most people do not want a studio level high DRR. It sounds awful and getting the RT60 that low will impact speech intelligibility and destroy the pleasing ambience of music.

 

[NTK]

Higher DRR, for 2 channel stereo, will mean a worse phantom center interference dip.

 

[DVDdoug]

That terminology is from the pro world and this is from Floyd Toole's book:

Main monitors
Large, usually in-wall installed, powerful full bandwidth systems capable of very high sound levels.


Mid-field Monitors
Medium-sized loudspeakers that may be full bandwidth or may use subwoofers, localized at moderate distance in front of the main console, positioned to minimize reflections from the working surfaces.

Near-field monitors
Small loudspeakers placed on the meter ridge of the recording console. The reflection for the working surface is part of the sound heard from thee loudspeakers, and their locations may cause them to interfere with what is heard from main or mid-field monitors. Listeners are in the acoustical near field of the source, meaning that the small changes in head location cause changes in the sounds arriving at the ears.

Personally, I like big speakers (capable of plenty of full-range output) in a big room but I have big speakers (plus a pair of 15-inch subs) in an average living room.


Note that for home theater, you need a separate subwoofer for the "point one LFE channel". The LFE channel is not included in the downmix so without a sub you only get the "regular bass".

 

[Keith_W]

Rather than that unhelpful and lame reaction, perhaps you would be more convincing if you could cite evidence of your own. My assertion that there are different DRR targets and RT60 targets for domestic listening and recording studios is backed up by Toole, Everest, and formal specifications such as DIN 18041 and EBU 3276.

 

[TheZebraKilledDarwin]

Rather than that unhelpful and lame reaction, perhaps you would be more convincing if you could cite evidence of your own. My assertion that there are different DRR targets and RT60 targets for domestic listening and recording studios is backed up by Toole, Everest, and formal specifications such as DIN 18041 and EBU 3276.

I had offered the best evidence in the world: a test with your own ears.
And you ignore it and ask for evidence from authorities...
Exactly because of that mentality Dolby can dare to sell reflection speakers without losing any credibility, because authorities tell you: take the vax and the booster, it helps you, instead of simply checking reality and using the own brain to connect the dots...

"What do the authorities say what I am hearing?"

But even if you would be deaf, and therefore ignore my simple tip, just using common sense would make you think twice, before spreading the worst advice ever:

1. EVERY professional auditorium for playing back ready mixed sound (i.e. cinemas, studios), all over the world, is using acoustically treated rooms.
2. These auditoriums exist to make money.
3. Acoustic treatment costs money.
4. Why are cinemas wasting huge sums in acoustic treatment to get the direct sound up, if it degrades the sound?


Why uses EVERY music production facility acoustically treated rooms?

All acousticians, people of practice building every successful production facility and studio, would be nothing else than hifi cable-sound or reflection-speaker sellers.

To be able to hear the ambience of the instruments in a mix, the indirect sound must not exceed certain levels.
My simple tip to move closer to the speaker will also show everyone who is not deaf, that at a certain distance the sound begins to improve dramatically: that is just when the direct sound becomes loud enough, so that the influence of the room no longer masks the reverbs and ambiences in the mix. That's when the details begin to appear. Then the listening even begins.

Most people do not want a studio level high DRR. It sounds awful and getting the RT60 that low will impact speech intelligibility and destroy the pleasing ambience of music.

I wonder if you have never recognized by using headphones, that all ambience of every instrument is already in the mix?

And people here asking for advice how to improve the sound, are not asking for studio level DRR. Studio level DRR is also not sounding bad, as you claim. It sounds great. But it is very expensive, and not necessary: because a consumer does not need to hear if the RT60 of the room algo sounds better with a decay time of 400 instead of 500 ms and the wet signal reduced by 15%, and an added predelay of 30 ms.
Ofcourse it sounds even better, if a setup allows to hear that, but that level of detail is not necessary. But being able to hear the room in the mix of each instrument, and where it is positioned, that is the basics of a good sound, called hifi.

 

[NTK]

I had offered the best evidence in the world: a test with your own ears.

You are talking to the wrong crowd. We are not that ignorant.

 

[Keith_W]

I had offered the best evidence in the world: a test with your own ears.
And you ignore it and ask for evidence from authorities...
Exactly because of that mentality Dolby can dare to sell reflection speakers without losing any credibility, because authorities tell you: take the vax and the booster, it helps you, instead of simply checking reality and using the own brain to connect the dots...

"What do the authorities say what I am hearing?"

But even if you would be deaf, and therefore ignore my simple tip, just using common sense would make you think twice, before spreading the worst advice ever:

1. EVERY professional auditorium for playing back ready mixed sound (i.e. cinemas, studios), all over the world, is using acoustically treated rooms.
2. These auditoriums exist to make money.
3. Acoustic treatment costs money.
4. Why are cinemas wasting huge sums in acoustic treatment to get the direct sound up, if it degrades the sound?


Why uses EVERY music production facility acoustically treated rooms?

All acousticians, people of practice building every successful production facility and studio, would be nothing else than hifi cable-sound or reflection-speaker sellers.

To be able to hear the ambience of the instruments in a mix, the indirect sound must not exceed certain levels.
My simple tip to move closer to the speaker will also show everyone who is not deaf, that at a certain distance the sound begins to improve dramatically: that is just when the direct sound becomes loud enough, so that the influence of the room no longer masks the reverbs and ambiences in the mix. That's when the details begin to appear. Then the listening even begins.



I wonder if you have never recognized by using headphones, that all ambience of every instrument is already in the mix?

And people here asking for advice how to improve the sound, are not asking for studio level DRR. Studio level DRR is also not sounding bad, as you claim. It sounds great. But it is very expensive, and not necessary: because a consumer does not need to hear if the RT60 of the room algo sounds better with a decay time of 40 instead of 50 ms and the wet signal reduced by 15%, and an added predelay of 30 ms.
Ofcourse it sounds even better, if a setup allows to hear that, but that level of detail is not necessary. But being able to hear the room in the mix of each instrument, and where it is positioned, that is the basics of a good sound, called hifi.

So much ignorance in this post. I'm not even going to bother debunking it. Go read Toole, then we can talk.

 

[TheZebraKilledDarwin]

So much ignorance in this post. I'm not even going to bother debunking it. Go read Toole, then we can talk.

You are talking to the wrong crowd. We are not that ignorant.

That is not ignorance?

 

[TheZebraKilledDarwin]

Just for the record, although it has been a few years I have read the book, I still have it at hand and we can discuss any aspect of what Toole writes, or not, where he might be interpreted wrongly, or even words are put into his mouth...

What I find really strange is the fact, that some like to reference Toole's work, but when the chance arises, to support the claim about his book with facts, the discussion what he really says and what not, is avoided, instead of proving the point.

It reminds me a lot about dicussions about hires audio or Dolby reflection speakers. A certain spin, which coincidentally always has the effect of directing potential cashflow into buying more equipment and not getting the acoustic basics right. I find it outrageous to see Toole's work being interpreted only in that specific way.