Rational Acoustics SMAART Training.
(A.K.A Adventures in Becoming a Better Sound Communist)
As the summer of 2012 slowly came to an end, we at UCI Sound decided to jumpstart our thinking machines by hosting Jamie Anderson from Rational Acoustics for a three day SMAART training class. Though I have a Louisiana public education, I am not spelling Smaart wrong. SMAART stands for Sound Measurement Acoustical Analysis Real Time. It is a brilliant piece of measurement software that we use here at UCI to understand and quantify what our systems our doing in the room they are in. Smaart is an industry standard in measurement software and, as we learned, it can serve as a valuable tool for system design and optimization. Over the course of three days we learned a tremendous amount about theory, application, and use of the software.
Day 1 began with an exploration into the fundamentals of sound. This was a wonderful opportunity to review and revisit many of the topics we discussed at the Meyer Seminar earlier in the summer. It is always great to have a refresher and further understanding the physical properties of how sound works. Jamie broke down the system design timeline into six parts. He also reminded us that often as sound practitioners we are thrown into the creative process at various points along the process.
The six points to good system alignment are
1. Concept/Artistic goal- (What are the artistic needs of the piece of art? What story does the system need to help tell?)
2. Venue Evaluation/ Modification- Where is the performance taking place? What are the acoustical/physical limitations of the space?
3. System Design/Equipment choice- Make sure you have the right equipment for the job.
4. Equipment Verification/Installation-Once the equipment is installed verify that it works. SMAART is a great tool for verifying problems within the signal chain.
5. System optimization/ Tuning/ Voicing- The process of voicing a system to meet the artistic goals and demands of a production. For example, a rock show might want to have a heightened low end to provide that “punch” to the kick and the bass. This is where Smaart really excels. Using the various forms of measurements, Smaart gives the designer valuable information that can aid in tuning/ alignment.
6. Realization, Use, Adaptation- We have all seen the engineers at FOH constantly looking at their RTA or Transfer Measurements. Because we don’t work in perfect environments the sound is constantly changing. We have to be able to adapt the system to the conditions of the night. Every show is different. Smaart is a great tool to monitor and understand system response during the show. Especially with the use of wireless microphone a system tech could literally walk around with an iPad and capture traces all around the space for reference. The possibilities are endless.
During day one Jaime said that the goal of the training was to become a better “Sound Communist.” We want everyone to get the same show. Yes..... this is impossible, but I feel it is a great thing to strive for. So, embrace/ strive for equality in your systems. Day one was filled with a ton of information about the Smaart interface and some techniques on getting better measurement data.
Smaart does two forms of measurements. The first is single channel measurement. These measurements are absolute. A spectrum measurement is one type of single channel measurement. For example a mic would go into Smaart and analyze the frequency response of the speaker at that given location in the space. These measurements measure frequency and amplitude. The time domain is excluded.
Smaart also performs dual channel measurements. These measurements help dive into the guts of a system. They can help solve problems within the time domain as well as show the differences in frequency response from what is being sent to what is actually being produced though the air. The transfer function is a great example of a dual channel measurement. In this measurement, a reference input signal is compared to a measurement on the output (i.e. direct pink noise from a console is sent into Smaart as a reference and out of the speaker. The second channel would be a microphone measuring that signal out in the house). Smaart then compares the differences of the two signals to formulate a transfer function. The phase response and spectrum response of the data are then graphically represented within Smaart. What makes this measurement so powerful is it takes the time domain into account. With this information we can decipher the phase response and arrival times of sources. We can even determine the polarity of a speaker using the impulse response.
At the end of day 1 a lot of our minds were blown at the fact that Smaart will easily average numerous traces. This is useful and gives the engineer a better understanding of the average response of a system in a given area. The process of averaging is done by taking multiple traces in a given area; then, within a menu in Smaart, the user can select those individual traces and average them together. A graphical average will appear and show the overall trend of response. The averaging feature is quite useful in showing any big issues within a system. Going after the big issues is much more effective than going after the small stuff because every seat is different.
Jaime has a great phrase for discussing prioritization: “Rocks, Pebbles, Sand, ……Beer.” In order to be better sound communists, we should tackle the big problems first. Once the big problems are solved, then we can work on the little things if we get the time. Of course, beer must happen after a long day of alignment. Do make time for that.
The second day was where we really learned how to utilize Smaart. In the morning, we took many different measurements and put Smaart through its paces. Here at UCI, we often use Smaart for tuning. Jamie showed us many tips and tricks of better navigating the interface. After our measurement calisthenics and lunch we started utilizing Smaart to set crossovers and exploring the impulse response trace.
The Impulse response measurement is a powerful measurement. It is a dual channel IFT measurement that measures amplitude over time. Why is this useful? Well an impulse response can show your arrival times of reflections, other speakers, other drivers, and even polarity.
(Above is an example of an impulse response measurement. The large spike is the first arrival of sound. The smaller spike represents a later arrival.)
Day three was a practical application day. Instead of sitting around and talking theory, we came up with some practical applications for using Smaart. Before we began, Jamie made a point to discuss reference microphones. Thru the whole seminar, we were using various measurement microphones at various price ranges. The lesson we learned was that though these microphones have a difference in frequency response, noise floor, and price, they can still get the job done for measurement. The frequency response curves for every microphone had differences in the high end past 5k. This difference in frequency response is minimal to the difference in response one would get by moving the microphone and inch in any direction. Also, Smaart can import data correction curves to flatten out the response of a microphone. So…in the live environment an $89 microphone will perform quite well for measurement. Where you do run into problems is that the sensitivity and noise floor of cheaper microphone is often less desirable than the more expensive quality measurement microphones. Yet, as a grad student on a budget, it was comforting to hear that an $89 microphone could get the job done.
The Smaart training seminar was an amazing opportunity that allowed us to further familiarize with the powerful tool. More importantly, we were reminded that the journey to good sound is a constant leaning process. We learned a ton and it was a great way to start off the year. I know all of us will utilize the things we learned for the rest of our careers. A big thanks goes out to Jamie Anderson and all at Rational Acoustics for an amazing three days of learning. This has helped us grow as artist, sound practitioners, and sound communists. Thanks for the fun.