Hi,

I've been asked to record a round table discussion and I'm wondering what would be the best way to handle audio recording. The people participating do not want to have to pass a microphone around form person to person and I'm not capable of micing everyone. The only mic I have is a shotgun mic (other than a lav) and I was thinking of putting the mic on a boom pole and a stand and having it be sort of suspended in the middle over the table. The microphone I have is Sennheiser K6. It will be like 6-8 people at the table. What do you think of this set up? Is there a better way of handling this?

Thank you
Kathy

" Is there a better way of handling this?"
- In lieu of lavalieres for the participants and only one boom mic being available, hire an experienced boom op. If an unskilled boom op is all that's available, a stand-mounted mic would be better IMO. If you can get hold of a cardioid capsule for the Sennheiser, it would yield a more even/wider pick-up.

" Is there a better way of handling this?"
- In lieu of lavalieres for the participants and only one boom mic being available, hire an experienced boom op. If an unskilled boom op is all that's available, a stand-mounted mic would be better IMO. If you can get hold of a cardioid capture for the Sennheiser, it would yield a more even/wider pick-up.
Hi Rick,

Thanks, I didn't mean that there will be someone holding the mic. The mic will be on a stand.

Just found out that I can get a hold of Sennheiser MKH 70 p48. How would that mic work for this situation?

The MKH 70 is a premium mic, but it's a long shotgun and very directional.

Could you get an MKH 40 cardioid? That would be more suitable if you're limited to one mic on a fixed stand.

You could also add the Sennheiser ME64 cardioid capsule ($170) to go on your K6 power supply.

The room's acoustic properties are going to be critically important to this working with any degree of quality sound since you'll be micing most of the participants at a much greater than optimum distance.

Could you have one directional mic on an overhead stand aimed at the moderator if there is one?

Then a second wider mic on an overhead stand to cover the rest of the participants equidistantly?

How many cameras (and separate recording channels) will you shoot with and how will the people be arranged around the table?

In addition to the room needing to be very quiet and acoustically soft to reduce reverberance, you'll need as clean a mic, preamp and recorder as possible.

Each mic you use will need to be recorded to a separate channel, with that separation maintained into the editing process, where careful editing of each track can cut down on cross-talk between closer mics and distant mics depending on who is speaking at the time.

A shotgun is the least effective mic for this type of situation UNLESS it's being aimed by someone for each Q&A that comes up. Being such a narrow pattern means that if two people are talking and they are only a few degrees apart, you're going to have a compromised capture. Omni mics are your friend here, and multiple mics placed every two people are really the better option (not best, but still better).

Renting mics and short mic stands might be the way to go, but you still need a mixer and someone manning the controls.

If this isn't in the budget, my recommendation is to put a small Zoom H1 or similar recorder between every two people and then in post you'll have to sync them and choose the strongest mic signal at the time. These recorders are small, cheap (about $100) and nearly idiot proof when set to auto.

Room acoustics is another factor. A well padded room (acoustically dead) will give you a cleaner sounding audio. A room that is already noisy, and where people are shuffling papers, sniffling, coughing, typing or having side conversations means you'll really be on your toes to get clean audio.

We had a similar thread a couple of months back and my own experiences, and I think the general consensus was that a boundary layer/pressure zone mic would be best for this type of recording. It is what they are specifically designed for, being placed on a hard flat surface like a table to pick up all round with minimal room reflection.

If you google for them, you will find a number of manufacturers producing them, including Audio Technica and Crown. Prices vary considerably, but a mid priced one should do the job well. Always a very useful mic to keep in your bag for recording table discussions and meetings.

Roger

I do not have a control of the room. It's not acoustically dead. I have to make the best out of what it is. There will be a main speaker, who will be wearing a lav mic as he will give a 20min presentation and then there will be a discussion at the table. I can only record 2 separate channels. There will be 2 cameras one shooting continuously (wide shot) and the other will be just doing close ups (b-roll) on the participants.
I also have 1 zoom recorder but I'm not sure if this will be any helpful here
There will be 13 people.
I could buy the ME64 capsule.
I was just told that this is going to be a casual/informal conversation with people having a drink and talking so I should not worry about the room being perfectly quiet etc. I just want to make sure I get a decent recording of everyone. Can I accomplish this with one K6 with ME64 capsule?

We had a similar thread a couple of months back and my own experiences, and I think the general consensus was that a boundary layer/pressure zone mic would be best for this type of recording. It is what they are specifically designed for, being placed on a hard flat surface like a table to pick up all round with minimal room reflection.

If you google for them, you will find a number of manufacturers producing them, including Audio Technica and Crown. Prices vary considerably, but a mid priced one should do the job well. Always a very useful mic to keep in your bag for recording table discussions and meetings.

Roger
I don't want to put the mic on a table, can I suspend it over the table?

We had a similar thread a couple of months back and my own experiences, and I think the general consensus was that a boundary layer/pressure zone mic would be best for this type of recording. It is what they are specifically designed for, being placed on a hard flat surface like a table to pick up all round with minimal room reflection.

If you google for them, you will find a number of manufacturers producing them, including Audio Technica and Crown. Prices vary considerably, but a mid priced one should do the job well. Always a very useful mic to keep in your bag for recording table discussions and meetings.

Roger

How about 2 of these mics? One on each end of the table?
https://www.bhphotovideo.com/c/product/126758-REG/Shure_MX393_O_MX393_O_Omni_Directional_Boundary.html

The Shure boundary mics are extremely good and one at each end of the table would give good coverage. They need to be on a flat surface for best results, but are quite incospicuous compared with conventional mics and of course don't require any sort of stand. You coiuld record directly to camera, to a sound recorder, or take the feeds to a transmitter.

Roger

The Shure boundary mics are extremely good and one at each end of the table would give good coverage. They need to be on a flat surface for best results, but are quite incospicuous compared with conventional mics and of course don't require any sort of stand. You coiuld record directly to camera, to a sound recorder, or take the feeds to a transmitter.

Roger

thank you, I'm going to order these microphones now

I'm just wondering whether it makes sense to mic the person who is going to do a short presentation separately or just let these pics pick up his voice so everything sounds relatively the same.

Always separate the tracks when you record them. If an open mic starts picking up lots of noise and you're mixing it with the presenter, there is no way to separate them in post.
The boundary mics are a good start, you'll probably want to use at least two and record them to a portable mixer/recorder like the Zoom H6. Not much different at that point from using multiple Zoom H1's, as you'll have work to do in post to pick the best audio track. Leaving them all open means you pick up random noises in addition to the signal that you want to keep.

If you're dealing with 2 tracks on your camera, devote one to the presentation, the 2nd one to one of the boundary microphones, and you can use a zoom on the opposite site of the room (mixing in post as needed). Adding 2 more Zoom H1's is still cheaper than adding 1 boundary microphone.

I did this exact same thing just last week, and the Zoom had better signal than the boundary mic (which still picks up much of the table noise/thumping, etc.). I would recommend a bit of rubber padding like a mouse-pad under any boundary mic, which will help to isolate those thumps.

I've got an old Shure ST6000 conferencing unit that has 6 mic inputs. It's able to focus on only one mic at a time (based on volume I guess). Maybe some system like that can be rented.

Always separate the tracks when you record them. If an open mic starts picking up lots of noise and you're mixing it with the presenter, there is no way to separate them in post.
The boundary mics are a good start, you'll probably want to use at least two and record them to a portable mixer/recorder like the Zoom H6. Not much different at that point from using multiple Zoom H1's, as you'll have work to do in post to pick the best audio track. Leaving them all open means you pick up random noises in addition to the signal that you want to keep.

If you're dealing with 2 tracks on your camera, devote one to the presentation, the 2nd one to one of the boundary microphones, and you can use a zoom on the opposite site of the room (mixing in post as needed). Adding 2 more Zoom H1's is still cheaper than adding 1 boundary microphone.

I did this exact same thing just last week, and the Zoom had better signal than the boundary mic (which still picks up much of the table noise/thumping, etc.). I would recommend a bit of rubber padding like a mouse-pad under any boundary mic, which will help to isolate those thumps.

I have one H4N zoom recorder, but 1 won't help me, I would need two, right? Where do you put the zoom, just lay it on the table? Are you saying the the internal zoom mics are better than the boundary mics? SO ultimately, would I be better off having two zoom recorders on the opposite sides of the table instead of two boundary mics on the opposite sides of the table?

I'm a little puzzled here, in that you haven't even told us the rough dimensions of the table (is it round, square, a long rectangle, etc.?), nor have you told us whether the presenter will be seated at the table or somewhere else in the room.

Let's assume the presenter is NOT seated at the table. Then mic his lav on a separate channel, all by itself.

I think boundary mics are a good choice for this, so if you're going to buy a pair, do not mix them together; record them separately on the two channels of your Zoom.

In post, obviously, first sync everything together. Take only the presenter mic when the presenter is speaking. When someone at the table is speaking, pick whichever boundary mic has better audio, and use only that one mic. Do not ever mix the two boundary mics together, or you may have phasing issues between the two of them (as well as additional noise and reflections from the room).

You could probably find some less expensive boundary mics if you're pinching pennies, but those Shures are certainly decent mics.

I'm a little puzzled here, in that you haven't even told us the rough dimensions of the table (is it round, square, a long rectangle, etc.?), nor have you told us whether the presenter will be seated at the table or somewhere else in the room.

Let's assume the presenter is NOT seated at the table. Then mic his lav on a separate channel, all by itself.

I think boundary mics are a good choice for this, so if you're going to buy a pair, do not mix them together; record them separately on the two channels of your Zoom.

In post, obviously, first sync everything together. Take only the presenter mic when the presenter is speaking. When someone at the table is speaking, pick whichever boundary mic has better audio, and use only that one mic. Do not ever mix the two boundary mics together, or you may have phasing issues between the two of them (as well as additional noise and reflections from the room).

You could probably find some less expensive boundary mics if you're pinching pennies, but those Shures are certainly decent mics.
Sorry, the table will be rectangular (I don't know the size). The presenter will be at the table but I'm guessing standing up. I don't know for sure, though. One of the shorter sides should be available for my camera, so the people would really just occupy 3 sides of the table, the two long ones and one short side.
I wasn't going to mic the two boundary mics together. I was planning on recording all mics on separate channels. Since I have two channels on the camera, I thought I would record the two boundary mics to the camera and the main speaker could be recorded to the H4N. Originally I was just going to have 2 mics but I since I have a Zoom recorder I thought of utilizing it to gain an extra channel.

What model of cameras will you be using so we'll know their audio capabilities?

Will you have access to a mixer, especially one that has multiple outputs so that both cameras and the "extra" channel of the H4n can have clean, strong audio to aid in synchronization on the timeline and simply benefiting you during logging, cutting, checking lip sync when you cut down to smaller bits of video etc.

For example, even a small mixer like a Mackie 1202-VLZ or equivalent would allow the appropriate mics to be preamped cleanly and sent separately during either the presentation or the discussion to both channels of both cameras as well as separately to the H4n.

In other words, having weak onboard audio on one of the cameras and lavalier-only audio with very weak pickup of the group on the H4n will increase the burden of logging, initial sync, editing decisions, lip-sync in closeups if you have drift, etc.

If I was doing this project, I would use a mixer, the two boundary mics, the presenter's lavalier, and a separate clean cardioid overhead mic (ME64 or AT4021) as a backup.

For the presentation portion, the lavalier would be sent to both cameras and the H4n. The backup overhead mic would go to the second channel of the H4n.

For the group discussion segment, the two boundary mics would each be fed separately to both cameras. The lavalier and the backup cardioid over the group would be sent on separate channels to the H4n.

The goal is to always have a clean strong signal from the mic that's most helpful to syncing your camera shot, even if it's only used as a guide. Having extremely weak guide audio is a royal pain.

Just to reinforce the value of boundary mics in the situation you are talking about, a Zoom H1 instead of a boundary mic will not be sufficient. The point of a boundary mic is that it will considerably reduce pickup of room reflections because ot the way that it picks up the sound waves. Room reflection of the sound being recorded is the problem in this type of recording. Have a quick read up on the way they work and you will see why. Certainly use a lav on the speaker, as his presentation will be the one that needs the clearest sound, but don't expect too much from a suspended overhead mic, as this will again pick up all the reflected sound within the room, although always useful as an emergency backup.

I agree with Greg that there are a number of considerably cheaper alternatives to the Shures and for many years I used the Tandy/Realistic PZMmics which were incredibly cheap but gave great results, but probably no longer available.

Roger

The Audio Technica Pro44 boundary mic should give similar results to the Shure and they receive good reviews at a much lower cost than the Shure. Here's a link to it at B&H https://www.bhphotovideo.com/c/product/168029-REG/Audio_Technica_PRO44_PRO_44_Hemi_Cardioid_Boundary.html/?gclid=CMat74irw88CFUI_Gwodc8cGlw&c3api=2572%2C113041916107

Roger

Agree with Roger, the Realistic PZM's are legendary for round table work, I've used them many times, there are 2 on eBay in the States for around $50 BIN.

At this point, I'm not concerned about the cost. The Shure's are coming tomorrow. I will be recording to Canon XF305 and lav will be recorded to Zoom H4N. I will not be using a mixer. The second camera is not going to be stationary. I will not be recording clean sound to it, just whatever the internal mic will pick up for syncing purposes.

The XF305's have pretty good audio circuits.

The Shure boundary layer mics have very good specs for high signal to noise ratio, but I have only used Crown and Audio-Technica models. I still have my two original Radio Shack PZM's as well.

Based on the specs, the Shure's should be a good choice.

Can you use a clapper for a sync mark at the start and at the end of the recording? That will help if not sending full volume guide audio to all devices, as well as giving a better idea of how much drift you're having with the H4n compared to the cameras.

Also put as much effort as possible into softening the room with whatever material or padded furniture is available.

Good Luck!

The XF305's have pretty good audio circuits.

The Shure boundary layer mics have very good specs for high signal to noise ratio, but I have only used Crown and Audio-Technica models. I still have my two original Radio Shack PZM's as well.

Based on the specs, the Shure's should be a good choice.

Can you use a clapper for a sync mark at the start and at the end of the recording? That will help if not sending full volume guide audio to all devices, as well as giving a better idea of how much drift you're having with the H4n compared to the cameras.

Also put as much effort as possible into softening the room with whatever material or padded furniture is available.

Good Luck!
I only have one sound blanket. I'm not sure how much it will help me. I need to put it somewhere where it doesn't show in the shot. Can I put it under the table?

Under the table is probably the least effective place. You want to put it where the sound waves will hit it, and where it will cover a reflective [hard] surface. Under the table, you already have legs and laps, some (or all) of which are wearing pants, chair seats (hopefully upholstered) and, hopefully, carpet. The sound waves will first have to bounce off a wall to get down there in the first place, so that's a pretty useless location.

Just pray that nobody is farther than arm's length from the nearest mic, and that the room is pretty big and diffuse, and with absorptive tiles on the ceiling ... at the very least.

Another concern nobody has mentioned is noise from mechanical systems (HVAC, etc.). Boundary mics will *not* help with that; they *will* pick up that noise clearly. The only thing that helps with mechanical noise is minimizing the mic-to-mouth distance so you can run your gain as low as possible.

Believe me ... I just spent a few hours cleaning up an 8-minute clip recorded in a live room with unbelievably high levels of LF noise from air handlers and cooling equipment. The mic was positioned about three feet from the talent, or so I am told. I was not permitted in the room because of some poorly-defined "intimacy" issues. (But I was allowed to hear the recording later ... go figure!!!)

I've been using this Audio Technica Boundary mic for many years : ATR97 Omnidirectional Condenser Boundary Microphone (DISCONTINUED) || Audio-Technica US (http://www.audio-technica.com/cms/wired_mics/e413b6d09db34276/)

Although it is discontinued, AT do have upgrades. I use it attached to a SenniTX hidden either in a bowl or gaffered under the table! I've used it for Round table and focus groups where I can trundle my XF300 around the "discussions". Combining its output with the on-camera mounted shottie supplies an urgent and "real" sound design. It's as if the viewer is in the room listening to the group.

It's given me great service and the output quality is way above its cost!

Grazie

Hi Kathy,

It would be great if you could come back on this to let us know how you get on with the Shures and the overall quality you managed to achieve.

Roger

Under the table is probably the least effective place. You want to put it where the sound waves will hit it, and where it will cover a reflective [hard] surface. Under the table, you already have legs and laps, some (or all) of which are wearing pants, chair seats (hopefully upholstered) and, hopefully, carpet. The sound waves will first have to bounce off a wall to get down there in the first place, so that's a pretty useless location.

Just pray that nobody is farther than arm's length from the nearest mic, and that the room is pretty big and diffuse, and with absorptive tiles on the ceiling ... at the very least.

Another concern nobody has mentioned is noise from mechanical systems (HVAC, etc.). Boundary mics will *not* help with that; they *will* pick up that noise clearly. The only thing that helps with mechanical noise is minimizing the mic-to-mouth distance so you can run your gain as low as possible.

Believe me ... I just spent a few hours cleaning up an 8-minute clip recorded in a live room with unbelievably high levels of LF noise from air handlers and cooling equipment. The mic was positioned about three feet from the talent, or so I am told. I was not permitted in the room because of some poorly-defined "intimacy" issues. (But I was allowed to hear the recording later ... go figure!!!)
Thanks Greg. Unfortunately, they don't' want to see the sound blanket so I could only think under the table. The room is awful for recording audio, one wall is all glass from the floor to the ceiling. I explained it to them and they don't care. I told them not to expect anything amazing in this case. There is no HVAC system.

Hi Kathy,

It would be great if you could come back on this to let us know how you get on with the Shures and the overall quality you managed to achieve.

Roger

The mics are coming today and I'm going to test them right away. I'm doing the recording tomorrow night. I'll let you know how it goes.

Here are two photos of the room this will be recorded in. The room will only have one or maybe two tables and there are things on the shelves now. I also believe there are vertical blinds on that big glass window. Not sure if the images help but any ideas what else I could do to that room to improve the situation? If I can convince them to use the sound blanket where can I put it so it's not in a frame? I will be shooting from where the fireplace is.

That's looks like a terrible room for sound recording! Hard to imagine anything worse. One glass wall, the other walls are hard, the walls are probably parallel (can't tell for certain from the perspective of those photos). The ceiling is hard, the floor is hard, there is not even any upholstery on the chairs. The room is even ugly and austere to look at, the chairs look terribly uncomfortable ... shoot the architect!

Cover all the glass with sound blanket, if possible cover some of the other walls as well. Carpeting on the floor wouldn't hurt.

I know, "I can't do that." So it's going to sound terribly live and audio quality will suffer. You cannot defy the laws of physics.

Mic each person with a lav, record them all on separate channels, mix accordingly. I know, "I can't do that."

If they want this just for archival purposes, it might be intelligible. Certainly nothing that I'd want to air at a later date.

Please excuse my bluntness. I've just gotten done with a client who ignored my advice, gave me a garbage recording, and expected me to "fix it in post." I made it better, but IMHO it still sounds sub-standard. I hate being associated with stuff like that.

Looks like an acoustical nightmare. Hard floors, ceiling, windows. You'll need quite few sound blankets. If you could rent a large piece of carpeting to cover as much of the floor as possible. If you could put some sound blankets on the walls and windows... but if you're relying on natural available light, the blankets will be an issue with that. In my experience, many of those type of rooms, the HVAC system can't be shut down in individual rooms, so extraneous HVAC noise may be another issue.

Yep I agree with Rick and Greg, an acoustic nightmare. Make sure that they are completely aware that the audio will not be good because of the room acoustics then at least they will know what to expect. If there are vertical blinds on the windows now then they may give a small amount of respite. You should see if you can angle the blinds to stop direct reflection of sound from the glass. You could also ask them if there are any alternative chairs available with soft backs to help reduce reflection.

I think that the boundary mics are the only type likely to give any sort of usable sound apart from the iimpractical solution of individual lavs. You could also try a reverb remover in post production, which I have had limited success with on some church sounds. Some eq tweaking in post may also help as a lot of room reflection is at the lower end of the voice frequency range.It may improve the sound at the expense of making it somewhat middly.

EDITED TO SAY you could put the acoustic blanket on the wall behind you for another minor improvement and I can't see them objecting to that as it will be out of shot.

Roger

I largely agree with Roger, with a few additional thoughts.

If the windows had actual fabric drapes, especially if they were lined, that might help somewhat. My experience is that thin hanging vertical blinds are insignificant; in fact they are often made of hard plastic strips which are acoustically reflective.

Yes, most room resonance is at the lower end of the speech frequency range. (Standing waves are largely to blame.) That specific room looks so live that I suspect the reflections extend to higher frequencies as well. I'll bet if you stood in that room and clicked your tongue, or said "tsk, tsk, tsk" you would hear distinct reflections of those high frequencies, too. That will smear the consonants and hurt intelligibility.

And Roger has an excellent suggestion: be sure to warn the client ahead of time, so that they are mentally primed to blame the room acoustics, and not you, if they are disappointed by the recorded audio.

There are audio systems, generally for bigger venues, where each speaker has a box and goose-neck microphone with a button on it. Only one or two mics can be enabled at a time. Something like that could work, as they'd be inches from the mics. I'd imaging that you can rent these systems.

A nice thing for the moderator is that you ensure that only one person speaks at a time. (Why don't we have these for presidential debates?) The difficulty is that people forget to use the systems and without training, they use the mics badly - either eating them or not addressing the mics at all. For this sized room, it would be especially hard to get people to remember to press the buttons - there's nobody in the back row to shout, "I can't hear you!"

So it's a long shot. But if the attendees and moderator got training before the event and would be disciplined enough to use the system reasonably well, you could get good results, even in that room.

https://en-us.sennheiser.com/integrated-systems-conference-systems-conference-digital-audio-equipment-adn

If this approach is a viable option, I wouldn't shop for specific products. I'd call the rental houses to learn about what they have.

Probably the biggest variable would be the moderator. If the person is conscientious and willing to ask people to use the mics and coach them in proper use in real time ("please use the mic system." "Please speak about six inches from the mic.") then it could be quite good. If the moderator can't be bothered, it could be a complete fail.

Boundary mics handle this so much better than other types so they'll probably work pretty well. After all, they are the choice of police station interview rooms where all surfaces are parallel and hard.

My own experience is that in meetings that are real as opposed to staged, the participants forget any guidance you give them on technical matters and will constantly talk over the top of each other. It is, exactly what it is.

Any form of boom is a real non-starter, because booms are reactive, so the vital first few words is always missed as the boom op works out who is talking, and gets there, only to find then the person at the opposite end reacts and he spends the session waving around, which is also very off-putting!

I tend to agree, Paul. I've used a delegate mic a number of times as part of my day job. I'm hyper-aware of audio presentation, so I do okay. Other attendees? Not so much. Without an attentive and gracious moderator, it's a fail. That said, this is the best way to handle open discussion meetings in very large rooms.

My concern about the boundary mic solution is the limited number of mics and channels. If the distance is too large, the far-away speakers will come through poorly. My experience with conference room mics is that 6 feet is the cutoff point. The sound might not be great at 6 feet, but it's easy to understand the speaker. Further away and low-signal, ambient sounds, echo cancellation, and noise reduction make communication difficult. In teleconferences, the person in the fourth chair or so ends up standing and speaking loudly to be heard over the phone. One might do a bit better with a clean, uncompressed recording and processing in post, but there would still be a big quality drop off after 6-8 feet.

Horrid.

OK:

1/- Move room/venue

.... If not acceptable

2/- Price-up pro audio company you know can do the job and get quote and inform client of extra cost.

. . if not acceptable

3/- Provide your solutions from what you've read here. This way, it leads client into knowing just what to expect and how you'd go about making a solution. Jon's experience might then be well heeded and registered by the client. You'd have paved the way. In my opinion you'd look both professional and caring towards your client's wishes.

Kathy, a lot of us (including myself) are giving you rather pessimistic comments. I have been speaking from the perspective of getting a "studio quality" recording, or at least a "good clean" recording. I tend to think in terms of the best quality voice recording, within reason. That may be an overly narrow expectation.

In retrospect, I don't think we know the end purpose of this recording. And that really matters. Does the client hope to incorporate it in some sort of low-budget documentary? Will they use it for a training video? Or is it just for internal documentation and archiving?

If the room sounds the way I imagine it does, I would hope the audio doesn't end up on a big screen. If it's just for archival purposes, I think it should at least be intelligible.

You originally said there would be a maximum of eight people. The table in your photos appears to be roughly four feet wide and eight feet long. So you end up with four pairs of people facing each other across the table. Two adjacent pairs make up a group of four people. There are two such groups of four. Put one boundary mic in the center of each of those groups. Then each person should be about three feet from the nearest mic.

In a wonderfully dead and quiet room, the above arrangement would yield pretty decent audio. In your room, there will be some reflections, the voices won't be pristine, but they certainly should be intelligible unless ...
(a.) people mumble badly, or
(b.) the room noise is uncommonly loud.
Keep your fingers crossed that neither one of those situations exists.

Just to fill in the missing detail, can you tell us what the client ultimately wants to do with the recording?

I work mainly in theatres, and without any doubt at all, the most common mic for picking up the actors on stage is the boundary type, usually PCC rather than PZM. For conferences I have a kit of table mount condensers - 12, on vibration reducing mounts. So each person, or perhaps a side by side pair of people have their own, and then the sound op is kept busy identifying who is speaking and reducing the level of all the others - never to zero to cover interruptions, but low enough to stop the nasty comb filtering effects that creep in with multiple mics close together. Where groups sit around the table - either circular, oval or rectangular or square, boundaries work again - and on long tables, one omni boundary per four people facing each other works, adding another for each extra 4 people. Boundaries are less prone to comb filtering, but it still can happen. With a recording, you can sort this in post - so not really an issue. For group work - with minimal kit, you can't beat them.

One thing to keep in mind with a boundary mic would be to avoid papers and typing if at all possible. Any sound right on the table will be loud.

We have a Bartlett stage mic for an annual young kid drama camp. The first year we used it, there was a western theme. They put straw all over the stage. Crunch, crunch, crunch. The director didn't think much of our mic choice. This summer, the concrete stage was clear, and people were very happy with the results. (I didn't hear the performance either time, so the results are hearsay.) The other improvement was that the loudspeakers were allowed to be in a better position this year, so we could use more gain.

Fortunately, you don't have a PA system and feedback to worry about. You can turn the thing up until it clips. (FWIW, the Bartlett mics have very low noise.) But you do have to worry about papers, typing, finger tappers, etc. But whatever method you use, you can bet a panel member will figure out a way to mess it up.

"Hi. I'm Chris. And I'm mumbling quietly into my hands while crunching on potato chips with my accent from the old country. I've now turned my back to the mic to walk far away from it where I will read an important and very long poem while performing a brisk physical activity with the cellophane potato chip bag. Also, sorry, I have this really bad cold. Sniff. Cough. Crunch..."

Ya know, a few of us have mentioned separately-tracked lavs, and of course that's an impractical amount of complexity. But here we are advocating using two boundary mics, which are more or less one mic for a group of four people. (Of course each mic will pick up all eight people, just at different levels.)

In reality, it would not be any worse to combine four lavs into one channel, and four more lavs into a second channel. Each channel would have four people {fairly close} and four other people {fairly distant and inaudible}. The final "four into one" mix would certainly be no worse than a boundary mic. And you'd end up with closer micing, a lot less tabletop noise, and less noise from mechanicals in the room.

You could probably get acceptable results from relatively inexpensive lavs ... some specific models have been recommended in other threads in this forum. Of course you'd end up with everyone plugged in and tethered, with wires to get tangled. I'll bet the audio would be as good or better compared to boundary mics ... even if it's a fairly unconventional setup.

Oh, wait ... did someone rule out lavs back at the beginning of this exercise? We still don't know the intended final use for this recording, either.

Re my post above:

Before someone mentions phasing issues between the lav mics, the setup I described should not violate the "three to one" rule. When a given person is speaking, his mic would be about 8" from his mouth. The mic on the person seated next to him would be at least 24" from the speaker's mouth.

You could improve on this if you distributed the mics on alternate channels. Then, when a given person is speaking, the mics nearest to him would be on the opposite channel, so they'd be potted down in the final mix. The nearest mic on the same channel would be at least 48" away from the speaker's mouth. That should make phasing issues non-existent.

I think the audio would be a little better than with boundary mics, because any given speaker would be picked up by a mic about 8" from his mouth, rather than at arm's length. Still, the complexity, and the tangle of visible wires in the shot, probably do not make this a better overall solution.

Meanwhile, I think Kathy's shoot was last night, so I'm eagerly awaiting her report on the results.

Thank you everyone for your help. The shoot happened on Friday and I was just able to look/listen to the recording this morning. It seems that the mics picked up everyone OK, everyone is intelligible but as everyone knew the acoustics of the room were horrible. The client was aware of all of this so no surprises there and they were OK with it. I put the mics on the rubber mousepads but they still picked up noises such as rustling paper etc.
They have asked me what could improve the acoustics in the room without destroying the look of the place. I suggested filling the bookcase with books, getting a big rug and what else can I suggest? The windows can't be covered and anything "ugly" that I add would have to stay out cameras sight. Would renting acoustical panels and placing them on the side where the camera is bring any significant improvement? The windows do not have vertical blinds. They have a mesh curtain which has very big holes in it, about 0.5inch squares.
What can I suggest?

It's a tough nut to crack. They want a room that looks stark and harsh ... it is going to sound stark and harsh. I'm glad they are at least aware of the problem and willing to contemplate some improvements.

You have to think in terms of surface area. Treating just one of the short walls, which is a very small percentage of the room's total surface area, will have a minimal impact on the room's acoustics.

Given that they aren't willing to change the long glass wall, I think the other long wall is the first candidate for change. There are various acoustical treatments that could be used. Certainly acoustical panels could be hung on the wall. Because of the amount of glass I'd suggest covering that long wall as completely as possible ... end to end, floor to ceiling. This could be done with something that is somewhat removable, like OC 703 panels. Or it could be a complete architectural refurbishing, by installing something like one of the Tectum products. Or it could be covering the wall with sound-absorbing ceiling tiles (properly spaced from the wall, with proper absorption behind them) but those are not as maintenance-free as a proper wall covering.

The next biggest area is the ceiling. It could also be covered with absorbing tiles with proper spacing and absorption, or with a Tectum product.

Of course either of the above will make some change in the room appearance, but some of the choices would at least keep the look of "a big white expanse."

Carpeting would help, but of course would not look like that beautiful wood floor. They may be very resistant to changing that. (I would be, if it were my floor!) Remember, surface area is key. Adding a 9' x 12' rug on that huge floor will make only a very small difference. If they keep the wood, that just makes it all that much more important to address the ceiling.

Treating one or both of the short walls would help somewhat, but again, they probably won't want to change the wood. They could install treatment on the wall between the bookshelves. That could be something like 1" thick 703 panels, manufactured to fit. It would not be immediately obvious, unless you looked closely. If the shelves are deep enough, there would still be ample room for books. (But they need to treat more than just this one wall!)

There is a lot of existing data for these various building materials, and a lot of formulas to help calculate reverberation time, etc. For that level of complexity you want to talk with an acoustician.

Of course any change is likely to involve building codes, fire and smoke ratings, etc. By all means make "recommendations" but don't put yourself in the position of giving them "specifications" because if you inadvertently violate some local building code that could come back to haunt you in a very big legal way. Before they make any permanent changes to the room they really should consult someone familiar with the regulatory aspects.

Thanks Greg. I know the glass wall is one of the biggest issues here. I'm pretty sure they just want to add/change decoration that would help with acoustics and not change any walls etc. This is a historical building and they will not alter it's original design.

There are a number of curtain and blind styles that would be quite sheer and translucent, to preserve the view but would cut down on acoustic reflections off the windows.

And/or, they could consider some wall-hangings on the opposite wall. Even some pure-white quilts would maintain the stark ultra-modern look, but soak up a lot of acoustic ambient reflections.

There are a number of curtain and blind styles that would be quite sheer and translucent, to preserve the view but would cut down on acoustic reflections off the windows.

And/or, they could consider some wall-hangings on the opposite wall. Even some pure-white quilts would maintain the stark ultra-modern look, but soak up a lot of acoustic ambient reflections.

I can suggest acoustic sheer curtains but as for the opposite wall, hanging pure white quilts would be an issue because they project on that wall. They will not install projection screen.

I'm a little puzzled here. They asked you for suggestions to improve the sound, but they are essentially unwilling to make any changes? Where would they put the "decorations" you mention, except on or in front of the walls? Certainly hanging two or three paintings (where, if not on the walls?) would not make a gnats bit of difference.

You've got three pairs of parallel reflective surfaces: a pair of long walls, a pair of short walls, and the floor/ceiling pair. You need to put absorption on at least one surface of a given pair. Again, since the long walls are the most surface area, that's the logical place to start.

Or you might try a triple-diffusion vacuum pump. If you suck all the air out of the room, the acoustical problems would disappear.