[AG-TECH] Microphone recommendations

[Jason Bell]

G'day Jeremy and All

Thought I might throw in my 2 cents worth about audio quality and the use of different microphones..

Firstly, a quick plug for the "Room Nodes Hands on Presentation (AG-Retreat Presentation 2006).ppt" which can be found at http://hpc.cqu.edu.au/menu.html?INDEX=index2.html&MAIN=usefulhpcdocuments.html which details various pros and cons about room construction.  Once aspect mentioned includes the use of various types of microphones.

But anyway, I would like to voice my personal opinions for this matter, as simple point form to highlight the pros and cons.

Wireless Mics:
--------------

Pros

*	Lapel radio microphone are good for presenters who require greater mobility;

*	Mobility, can be moved around the room for different setup's without the problem of trip hazards; and

*	Wireless microphones can be passed to participants at the back where desktop or ceiling microphones cannot hear the conversation.

Cons

*	Batteries are a constant issue;

*	For setups that use radio mic's infrequently, tend to have incorrect gain configuration and requires constant adjustment;

*	People speak into redio mic's differently.  IE, sound will place it too far away and be difficult to hear whilst others will almost swallow it, thereby causing overdriving; and

*	Some wireless mic's require passing a microphone from speaker to speaker, thereby stifling interactivity.


Desktop mounted Mics
--------------------

Pros

*	Provides greater depth to the quality of the speaker's voice.

Cons

*	Limited pickup range.


Ceiling mounted Mics
--------------------

Pros

*	Great for picking up audience participants and allows everyone to be heard. 

Cons

*	Ceiling microphones require more tuning;

*	Gain levels need to be set at a higher level, which can also introduce complications such as additional ambient noise; and

*	Due to distance from Microphone, voices may sound distant or hollow.

Special Note:  I know a lot of people don't like the use of ceiling mounted mic's, as there can cause poor audio and I will agree...  But if configured correctly!!!! can give you a lot of options, where the need for passing/moving mic's around all the time becomes obsolete.  


In my opinion, a combination of the use of the above actually provides the best overall results.  For example, using a couple of desktop microphones for high quality audio for presenters/main speakers and ceiling mic's to pick up audience / rest of the speakers works well.  This is how I have my AGs configured and I feel it works well.  Even though I don't use wireless mic's, I believe the use of lapel mic's can be very beneficial as well.

But with each Access Grid, each configuration is slightly different and the only way to find the best options is to TEST, TEST and do more TESTING.  Two way to help with the testing is by :

Placing the audio device on the display machine:

*	Provides visual feedback to the users; and

*	Allows users to easily adjust volume settings.

By setting up an AG on a laptop and using headphones, you can actually listen to each of the different mic's, so and adjustments of settings can be made where required.

*	Allows you to find optimal positions for the various microphones;

*	Allows you to adjust angles of ceiling mounted mic's to help remove background noise such as air-conditioning (I have had to do this personally); and

*	Allows you to personally test and achieve reasonable audio, before requiring feedback from external sources.

Of course, information on self testing AG nodes can be found at http://www.accessgrid.org/node/352

I apologize for this email being quite long, but I hope you find some of the information useful.

Cheers,
Jason.



From: Vine, Derek A [mailto:Derek.Vine at usd.edu] 
Sent: Friday, 2 February 2007 9:15 AM
To: John I Quebedeaux Jr; Jeremy Mann
Cc: ag-tech
Subject: RE: [AG-TECH] Microphone recommendations

I have had some experience with ceiling microphones in various Polycom conference rooms, and have not really liked the results.  When all is working as desired, the quality and clarity is very nice, a few mics can cover a 25 person room.  The biggest thing that you have to watch out for is the HVAC system in the room.  With the units I have used, whenever there is a conference in the room, the air exchangers need to be turned off so that it does not sound as though there is a tornado in the room.  Then, all of the participants complain that they are getting hot and the whole thing starts over again.  As for what to do about your issue with not wanting cords all over the room, I wish you luck.


Derek Vine
Communication Network Specialist
The University of South Dakota
414 East Clark Street
Vermillion, SD 57069
Office - (605) 677-5042
Cell - (605) 677-8215
ceddn at usd.edu



From: owner-ag-tech at mcs.anl.gov [mailto:owner-ag-tech at mcs.anl.gov] On Behalf Of John I Quebedeaux Jr
Sent: Thursday, February 01, 2007 4:18 PM
To: Jeremy Mann
Cc: ag-tech
Subject: Re: [AG-TECH] Microphone recommendations

Jeremy,

My 2 cents from experience is that wireless mics are an extreme pain to maintain due to battery consumption and also to control the appropriate use and placement and audio... balance? If at all possible, wire them for lower maint. particularly if they receive a lot of use. Wireless is much more expensive as well, but they are convenient (it would seem) until you begin dealing with batteries.  Also, if they're wireless and the mics are not in a fixed point then you have audio issues to deal with with microphone placement- including the famous picking up a wireless mic and holding it like a "StarTrek" communicator... <shudder>. Perhaps it's just me, but i like it if my users can NOT physically move the microphones that I've so carefully balanced for the acoustics in the room they are in.

I feel your pain on the wires though and in particular the microphone situation. Newer rooms here they don't want to have "fixed" mics on the tables and the tables themselves aren't fixed either (i.e. can change room config in a few minutes). I know that Jason Bell had demonstrated at SC Global his success at incorporating ceiling microphones into his room infrastructure. Perhaps some audio folks can comment on microphone placement and installation a bit for new installations.

-John Q.

-- 
John I. Quebedeaux, Jr.; Louisiana State University
Computer Manager LBRN; 131 Life Sciences Bldg.
e-mail: johnq at lsu.edu; web: http://lbrn.lsu.edu
phone: 225-578-0062 / fax: 225-578-2597


On Feb 1, 2007, at 8:59 AM, Jeremy Mann wrote:

I've been assigned to design and install AG systems in several
existing conference rooms for different departments here on campus.
One design they all agree on, is the lack of or sparse use of cables.
The one portable AG node I built several years ago is not pleasing to
the eye at all because of all the cables.

I'm interested to hear if anyone else has built or is using wireless
table top microphones, or  a combination of wireless microphones with
built-in echo cancellation.

Any brand recommendations?

-- 
Jeremy Mann
jeremy at biochem.uthscsa.edu

University of Texas Health Science Center
Bioinformatics Core Facility
http://www.bioinformatics.uthscsa.edu
Phone: (210) 567-2672