Mic Placement (stupid question?)

[stevea]

After doing this for 7 years or so, I'm finally - for the first time - going to try and add VR to my set-up. I've read through a ton of the threads here, and I've purchased a single PZM11LL that I plan to either run directly into the line-input of my sound card, or through a RLY8 relay if I get convinced I need to turn it on and off to avoid false triggers.

With a single mic, I'm wanting to place it in our great room where the entire family spends most of it's time. After looking at the layout of the kitchen, family room, and breakfast nook (components of the great room), I've found the wall I think would be the best place to mount it. However (here's the stupid question), it would be right under the left speaker of the whole house audio. I.e., when I start "conversing" with HS, is this going to cause a problem or some sort of feedback?

My instinct is that this is a very bad idea, but I figure it has to come up with others doing this, even though I couldn't find any thread on it. It seems like the same reasoning you would use for where you want to put the speakers is pretty close to the reasoning of where you would put the Mic. Am I crazy?

Steve

[anogee]

You might want to test it in the locations you are thinking, before installing it. I find that it works best in a relatively "dead" room that is very quiet when you are within 10 ft. of the mic and facing it. If your room has non-carpeted floors, has a TV, or the mic is a distance from the person speaking, it doesn't work well, if at all.

[dantelope]

Steve:

For any VR setup to work, you need to cancel out known noise sources as best you can. The recognition input needs be as clean as possible for even modest performance. That means if your mic can hear your whole house audio, then you're going to have to either:

1) Clean up the recognition input by mixing the mic input with the negative of the output from the whole house audio, OR

2) Turn off everything when you want to talk and pray there's not enough ambient noise to mess up the system.

My recommendation is to use an AP800 or similar device, run the mic into it, run the output of the whole house audio system into it, and then test it with the mic at the location where you want to do the install without installing the mic. If it works, then install it.

I don't know too many people getting positive results from an open-air mic without using a mixer.

My $0.02.

Dan

[Rotech]

Dantelope,

what are you using to connect the ap800? most computers (modern) dont have serial ports onboard, what is the trend to connect the ap to the pc?

Also is it adviceable to connect a two way stereo converter like the one called "cleanbox". since the ap has balanced inputs and the pc is unblanaced could that make a diference?

[stevea]

"I thought I knew nothing, but it turns out I was giving myself too much credit..."

I now am aware that I know less than nothing. I guess I need to go find out about mixers, an AP800 (is that a mixer?), and how to get a line-level negative of what is going to my speakers. It certainly sounds like I shouldn't put the mic where I thought was most handy.

I guess I'm starting to understand what is so hard about VR, and maybe why I didn't ever want to try it before. It almost sounds like the best way to make it work well is to put the mic in insulated sound-proof room that no one ever goes into. If I can't put the mic where everyone hangs out and "lives" (i.e., noise), it seems like VR is way less handy than just finding a computer and logging in. Hmmm...

Well, I've already bought the PZM11LL, so I guess I won't give up yet!

Thanks for the wisdom everyone. Keep it flowing, and I'll go get my reading glasses and my Visa card...

Steve

[dantelope]

Steve, don't get discouraged. It's not that bad.

Mic Placement
The mic should be where it will be most convenient to you, although you may need to adjust it based on other properties of the room. For example, the "ideal" room has the mic perfectly at mouth level (i.e., you don't need to look up or down for the maximum power of your voice to travel into the input) and has zero reflections (no wood floors, exposed windows, etc.) and minimal noise outside of your own voice. Of course, rarely is the most convenient place the most ideal, so you make do...

How to Get VR
In order for VR to work, the computer needs to take the sound it hears and analyze it against a vocal and syntactical pattern. If I tried to talk to you in a quiet room, you'd have no trouble hearing and understanding me. If I used that same voice in the middle of a busy New York street, you'd be spending most of your time screaming "Whhaaaatt!?!??!" -- which is exactly what your computer will do if you don't drown out that noise somehow.

So what you want to do is separate your voice from the rest of the world. That happens in two different ways:

First, you want to cancel out ambient noise. If you've never noticed the buzzing of your lights overhead, the soft hum of the air conditioner or heating unit, the sound of wind blowing in through the door, listen carefully. That kind of noise is "ambient" noise -- much like the ambient light you get from outside a window. That's pretty easy to deal with -- you apply a simple filter (low-pass or high-pass, depending on the noise source) and presto, it's minimized compared to the strong voice signal.

But after ambient noise comes "other" noise. Other people in the room. The television. Kids screaming from outside. Your dog barking. The radio playing loudly. And of course, feedback from the computer playing over a speaker in the same room.

Some of these noises you can manage, and some you cannot. Radios, televsions, and the computer speaker are all manageable. The other sounds are not. If you have the other kind rampant in your house or in the area where you've decided to place your microphone, install it knowing that you may have difficulty getting it to recognize what you're saying, or, worse, the occasional false positive where it recognizes your dog and opens up the garage....

The Role of a Mixer
An automatic mixer is the weapon of choice for VR. Typically used in conferencing solutions, an automatic mixer takes several microphones and allows them to transfer their inputs to one or more outputs while simultaneously doing two things: removing ambient noise and removing known noise sources such as the sound of the person's own voice feeding back through the speakers.

This is exactly what you want. The Shure SCM410/810 or the Gentner AP400 or AP800 are such devices and are highly recommended. There are others as well, but these four can be found, usually on the cheap, on eBay and other sources.

It works like this:

Things going INTO the mixer:
MY VOICE + MY STEREO + AMBIENT NOISE + PC SPEAKER

What the mixer does:
-MY STEREO -AMBIENT NOISE -PC SPEAKER

Things going OUT of the mixer into the microphone input on the sound card:
MY VOICE

Things going out of the sound card:
PC SPEAKER


It's really quite fascinating to listen to. You can stand in the middle of a room and, in a normal voice, say "Computer, turn the lights on". WHile the stereo is on full blast. And the TV is blaring. Because the mixer will subtract those two inputs from the mic input, it will hear mostly your voice. Some of the radio/TV will still make it through as the mic is picking up echoes from the walls and other delays that aren't present in the input, but it's a much, much cleaner signal in the end -- and if you listen to what the sound card hears you'll hear your own voice quite clearly with some quiet, muffled background noise.

Automatic mixers also act as routers, which means I can route my mic input to anywhere I want. For example, I have an AP800, which allows up to 8 microphones and several other input sources to be sent to up to 8 outputs (more actually, but let's keep it simple).

So when I speak into my microphone, a signal on the AP800 raises the voltage on one of the status pins. That status pin is being read by a digital I/O card and fed into the computer. The computer is running Homeseer. And Homeseer is running a script which can read the status.

So when Homeseer receives a voice event, it checks the status pins to determine which microphone caused the event. Now I can map that to the room which contains the microphone (e.g., The bedroom). Now I process the event and send my feedback to the speakers associated with the bedroom by dynamically re-routing the PC speaker to that rooms "output" on the mixer. That output feeds into an amplifier, which in turn feeds the speakers.

Presto. Open-air VR at your service.

I have mixed results with my VR despite all of this. At it's best, I had about 90-95% recognition rate success. Which if you think about it still isn't very good (that means I'm having a failure every 10-20 commands at best). So you definitely need to know that going in. But if you know that and expect it, you can really start to appreciate the power of open-air VR. I've been trying to get mine to do more than just VR -- a full-service intercom, room monitor, and phone interface. No such luck yet as other things have taken priority, but it's still somewhere on my list.

Hope this was helpful.

Dan

[dantelope]

Dantelope,

what are you using to connect the ap800? most computers (modern) dont have serial ports onboard, what is the trend to connect the ap to the pc?

Also is it adviceable to connect a two way stereo converter like the one called "cleanbox". since the ap has balanced inputs and the pc is unblanaced could that make a diference?

Hi, Rotech. Not sure where you got your information, but all modern PCs come with at least one serial port. As I have several serial devices attached, I've used a multi-port serial card to expand my system (I'm using a RocketPort, but there are others). They can be found for fairly cheap on eBay. I have an 8-port and a 4-port card, although I only use the 8-port (I over-purchased, as usual).

I use a simple stereo-to-Phoenix connector with solid balanced audio cable. Works pretty well.

Dan

[stevea]

Dan - Wow!

I need to go absorb all this. Thanks a ton.

I started looking on E-bay, and there are quite a few AP800's, but I didn't see very many AP400's. I think I found the manuals on-line (is Gernter and Clearone the same thing?). It seems like on the board here lots of people have the AP800, but not very many of other mixers? Is that an indication of people having more than four mics, or is there something else? Is the selection of the AP400/800 vs the SCM410/810 a religious one, or are they pretty similar for this application?

Now my real critical question: I bought this PCM11LL thinking I was going to do something very simple. Should I have not gotten a Line-Level mic? I'm guessing that I can send it back to Martin at Automated Outlet and get a regular one. I would expect that these mixers don't expect line-level, right?

Thanks again for the detailed explanation. I've got to go read it a couple more times!

Steve

[dantelope]

is Gernter and Clearone the same thing?

Yep, ClearOne bought Gentner way back. ClearOne has several newer products as well which are probably old enough now to find on eBay as well. Don't knock yourself out though... the AP400/AP800 works great.

It seems like on the board here lots of people have the AP800, but not very many of other mixers? Is that an indication of people having more than four mics, or is there something else?

The AP800 seems easier to find than the AP400. One would imagine that a device that supports twice as many mics as the AP400 would be twice as much money, but the cost differential really isn't that great. So most people tell themselves they are buying extra capacity for the future. You can chain multiple AP400s and AP800s together (mix or match) to create larger systems, though, so either way don't worry about it.

Is the selection of the AP400/800 vs the SCM410/810 a religious one, or are they pretty similar for this application?

When I first started looking into open-air mics, the expert I found used the Shure SCM810. I couldn't find one for cheap and found the AP800 instead. Moreover, I think the AP800 is probably a slightly better device than the Shure SCM810, but I have no real experience with the SCM810 so I can't be sure. Once you find a support group of folks that use one device, it's easier to stick with it because you can use their experiences, scripts, etc.

Should I have not gotten a Line-Level mic? ... I would expect that these mixers don't expect line-level, right?

Level refers to the relative strength of the signal and is measured in decibels. Line level sources are much-amplified signals over Mic level signals. Line level is usually between -10 to +4 dbm in strength while mic levels are normally -60 dbm.


The AP-series can use both line-level and mic-level inputs -- it's a configurable thing on a per-microphone basis. However, line-level inputs should not be sent over long distances (how long is "long" I am not sure), whereas mic-level can be sent over balanced cable to great distances. My master bedroom microphone cable extends from one end of my house in the basement, up to the attic, across the attic, and down to the middle of my wall on the second floor -- probably a 100' or so run. If I tried to do that with a line-level signal, the wire would probably be very, very hot (Danger, Will Robinson, Danger) and the signal would not probably make it to the AP800. My recommendation is to stick with mic-level inputs unless there's a good reason to do line-level. I believe the mics designed for outdoor use are frequently line-level, so that might be one use, but I'm not sure.

Dan

[stevea]

Dan,

More great data. You either type fast or are very patient with me. Either way you know lots of stuff that I can use. Funny I consider myself fairly advanced in HA, HS, ASP.NET, VB.NET, X10, etc. This VR stuff is like a whole new game....


I went ahead and bought an AP800 on EBay. Got it for $150 before shipping. I've already spent way more than I thought I would on this VR stuff, and I would guess I'm only starting!

Based on everything you said, I may be able to mount the Mic where I originally wanted (on the same wall with one of my whole house speakers, in the great room), if I can manage to get all the adjustments right on the AP800. (Adjusting the AP800 will probably a whole new topic for me to pick your brain on; I see lots of messages here.) *IF* that is the case, the placement of the Mic would be exactly above (one floor) my Homeseer machine, so the run of the Mic line would only be about 15-20 feet. Do you think I'd be OK with the Line-Level Mic, or should I contact Martin and try to exchange it for a regular PZM11? For that matter, should I get something other than the PZM11?

Thanks again for all your help!

Steve

[dantelope]

Steve, if you are an advanced user who can develop scripts and applications, then this is going to be a piece of cake for you I think. Once you get past the newness of it all, it's pretty basic stuff, I assure you.

As for the line-level vs. mic-level, 15-20 feet doesn't sound like it'd be a big deal. You might try it and see how your results are.

Others here have had good experience with some other mics, but the PZM-11 is my top choice. It's a phenomenal unit and can be painted so it blends right in. My only complaint is that it's an ugly nubbin even when it is painted.

If you're at all electrically inclined, you might do what I never did but wish I did -- use a double-gang box instead of a single-gang to mount it and use the second space to create your own control/status panel. I wanted a push-to-talk or mute button and status lights to tell me whether the mic was active, the AP800 was listening, HomeSeer running, etc. I still may do that if I ever get the time. Of course, by then we'll all be flying in our cars and homes will come standard with open-air mic systems....

In addition to the AP800, you're going to want some kind of digital I/O board. I use a simple one from WeederTech (WTDIO), but there are plenty of others around. This will allow you to do fast control and status on the AP800. You can always use the serial port protocol to do that, but the control/status pins are much faster and more convenient for some things.

I'm not sure if you can pass line-level down balanced audio cable, but get yourself some good audio cable. I got some from a friend and don't even know what kind it is. Paul Koslow has made some cabling suggestions on this board in the past, you might search for his posts (he is the expert, for sure).

[stevea]

Dan,

I guess I'll give the LL a try.

Funny, I was thinking about putting a stick-a-switch right next to the mic to give the the safety of being able to mute the speakers, turn off the mic, or both. I don't know what the AP800 can do for me, but I'm guessing I can command it to enable / disable the mic.

I guess I'm probably "electrically inclined". I've got a Master's in EE, although that was almost 30 years ago, and every since I got it I've been in the Software business. As a result, I'm way more comfortable in front of the keyboard than I am with the pliers. Still, I think I can get this to work.

Based on yours and others comments here, I think I'll wait until I get the AP800 before I start cutting holes the the wall for the switch box. I'll try to hook everything up in the basement next to the Homeseer machine while I learn the details how to tune the AP800.

I see you created a script package back in 2005 for the AP800, and it looks like you and others have continued to enhance it (what's an AP10?). I assume that would be a good place to start?

Steve

[dantelope]

We're pretty much in the same boat. I got an MS in EE as well but have been doing primarily software the past 18 years. Lol... seems like a common story.

One recommendation: if you can, just run the wire in plain sight (up the stairs, across the kitchen, whatever) to the mic so that you are testing the mic where it will be used. If it works in the basement that doesn't mean it will work in your target location.

The scripts will help out and are well-documented so you should be able to do whatever you need to do. There's a manual for the AP800 that fully describes the pinout of the status/control pins and the serial port protocol. It's fairly straightforward.

Good luck and keep us posted on your progress!

Dan

[anogee]

After spending much on two AP800's, open air mics, cables, and much time, for me it pretty much was a waste, but I use the mics to monitor my house remotely.

There really is three levels you can attempt. To do it 100%, you would need a AP800 in each room, with several mics, and each noise souce (TV, radio, HomeSeer voice) all cancelled out from that room. Then each room AP800 would feed into a master AP800 then to your PC. That would be very expensive, even at eBay prices, but it probably would work. Probably $5-10K to do the my house, maybe more.

Next level down is what I did. One AP800 for the full house, a mic in most rooms, and some of the house "noise" sources fed back into the AP800 for cancellation. This is what I think most have attempted, and what I have, and I'm only marginally happy with it. For me, in rooms with tile floors, VR is unacceptable because with the floor, VR never worked very well unless I was fairly close to the mic. Maybe 5 ft.

In rooms with carpret, good mic placement, and reasonable speaking distances (5 - 10 ft.) it works O.K. with MAYBE 50-70% accuracy for me and less for other family members.

The problem is not my setup, but really more the accuracy of Microsoft's VR with isn't designed for open air recognition. No matter how I tweaked, I could never get a good blend of recognition correctly and rejection of the incorrect. Maybe in a few years, as PC's get faster, and VR gets better, it will work better.

The lowest VR would be one mic, and that could work in a quiet area, but I'm not sure how useful it is.

But, all is not lost. I use my mic system with an AP800 for a type of intercom that works well, and I can monitor the mics remotely.

Also, the greatest thing since sliced bread is the AP800 controlling my room spreakers. I designed my own scripts to interface with the AP800, and that works great. Anytime I "speak" with Homeseer I control just which speaker(s) will say it, and the AP800 is so fast, I can control speaking with almost no delay. There is a speaker outside near my front entry, and I thank the UPS guy/gal for packages. I hear that the talking thank you is the big water cooler talk at UPS.

So anyway, my advice is good luck, and don't spend big bucks until you have proved that it will do what you want. VR looks great in the Jetson's, but the reality is not quite there yet, even with the AP800.

[dantelope]

Having a push-to-talk system would be much more accurate, albeit a little less convenient (and perhaps enough less to make unattractive depending on your desired goals). But that's basically what you have with the phone-based recognition and a wireless phone.

And what anogee says about flooring (and other room properties) is spot-on -- I would never attempt open-air mics in my kitchen, which have lots of windows, wide-open spaces, lots of crazy noise (refrigerator hum, dishwasher, people, etc.) and the worst possible materials ever (wood everywhere, no carpet). It'd never work.. which is a shame since that's the most useful spot for it.

An AP800-per-room... wow, anogee, that'd be sweet!!

Dan