Spectrum analyzer?

IMHO, the most pernicious effect of the room acoustics is the extended decay at certain frequencies. These frequencies are not necessarily those that show up as instantaneous magnitude peaks nor, if they do, is simply reducing the magnitude going to reduce the decay time appropriately. Ideally, one would like to have a room with a uniform decay time (analogous to RT60) for all frequencies but this is more difficult with small rooms (at home) than it is with large ones (concert halls).

Kal

Kr4...Thanks for your answers. Is there any device that can equalize delay at all frequencies? Anyway, I question your statement that delay should be uniform across frequency. In a highly reverberent hall, where delay is easy to hear, the tonal quality varies greatly as the sound dies away. In fact this variation is an essential characteristic of such sound. It wouldn't be realistic if it didn't happen that way.

There are many devices that attempt this with varying degrees of success. These include the usual suspects such as Audyssey, TacT, ARC and a slew of PEQs when coupled with RoomEQ Wizard. The one I like best is the Meridian MRC which measures the broadband decay above the Schroder frequency (~200-300Hz in most domestic rooms) and then calculates filters for band below that frequency. What is nice is the ability to adjust the decay target, to modify/delete/create filters and the ability to graph the results.

You are right about concert halls since there are effects there which are different from those in small rooms (short latency reflections, distance effects on frequency, etc.). Nonetheless, there is a definable RT-60 across most of the audible frequencies well into the bass in concert halls but small listening rooms have their low frequencies dominated by room modes below the Schroder frequency.

In addition, if you want to reproduce the concert hall acoustics when you play a recording of them, you do not want to superimpose the acoustical characteristics of the small room on them.

BTW, there's a great new book on all this from Floyd Toole.

Kal

I use and recommend SmaartLive (software on a PC) which is the industry standard for pro live sound work. In addition to RTA functions, it has real-time transfer function measurement . . . which is a much faster, more stable, and more accurate display mode than an RTA. Its FFT parameters include a FPPO (fixed-point-per-octave) setting, which greatly reduces the need to change FFT parameters to properly resolve the frequency domain of interest.

Phase and time-domain (impulse response) data are additional functions, and it can do so both with test signals or program material (music). It even has a good speaker-impedance testing function.

Hi, I think you are asking good questions and and you are headed in a good direction. There are probably a number of considerations but I think you can save some money and take a first pass with some PC-based software and a microphone. I've spent many years with hifi and several years ago after building my system to the max I got serious about figuring out room acoustics; the process convinced me that no matter how good your equipment is the room will be a huge part of the equation. If you start with some software and a microphone - and if you happen to get some equalizers so you can make the process interactive - you will get a very valuable sense for the challenge and importantance of room acoustics. After this first highly informative and relatively inexpensive pass at analyzing and correcting acoustics you might then decide to go on to room treatments or even a full room design - but I think you can learn a bunch with the PC software and a microphone; and while equalizers might not be the best or right long term solution, the ability to treat the signal (to perhaps a 1/3 octave level) and then see the results graphically on your computer and hear the results with your ears will add significantly to your knowledge and skill - which will help you make further decisions on how to best invest your time and money.

Check out these two older threads on audioasylum:

http://db.audioasylum.com/cgi/m.mpl?forum=speakers&n=177308&highlight=trueaudio&r=&session=

http://db.audioasylum.com/cgi/m.mpl?forum=speakers&n=178395&highlight=Yada&r=&session=