Guide
UoB – Hybrid Teaching – Microphone Technical Insight
Last week, we had the opportunity to share one of our recent projects from the University of Birmingham, a lecture theatre purpose built for the world of hybrid teaching. The video, which can be found here, gives a quick overview of the system and the features and benefits of the space.
This week, we’re taking a more technical deep dive into the system, to give insight into some of the technology we used to achieve this as well as some tricks for your own system.
Mic’ing up a 500-capacity lecture theatre is no easy feat, well, not typically! To achieve this with spot, ceiling or boundary microphones would be both costly and impractical to deploy. Beam-forming array microphones are no longer a new technology to the industry, but the real-life use cases and popularity continue to grow at a brilliant rate.
In Lecture Theatre 1, we managed to capture the entire audience area with just four of the Shure MXA910 arrays. Key to retaining the high-performance level of these microphones is suspending them within a suitable height for capture. Semi-contrary to logic, the higher that you suspend the microphones, the smaller the area that you can cover. This is due to a maximum distance limitation of around 6m from source to microphone, anything beyond this and intelligibility will start to decrease. Having said that, microphone coverage from 6 metres away is still incredibly impressive and thanks to the adjustable lobe widths on the microphone, you can still retain a tight coverage. Think of each lobe as a steerable shotgun!
Tip: When suspending the MXA910 at height, where possible, stick to narrow and medium beam widths. This helps to retain speech intelligibility and minimise reverberant capture. Just because you can cover large areas in Shure Designer with wide lobes, doesn’t mean that you should. See the below coverage map we used for LT1.
When commissioning a system, if using a floor plan within Shure Designer, ensure that both your scale and microphone positioning is entirely accurate. It can be tempting to organise the lobes by eye but a small miscalculation in scale or position can then very quickly lead to poor performance.
When on site, it is incredibly useful to have a test subject, someone that can walk around the space and sit in various seating positions for you, whilst you listen on a pair of in-ear monitors or headphones, to dial in the lobe position.
When moving the lobe, it should be audibly obvious when the lobe is accurately placed. Critical listening is key, paying particular attention to high frequency performance as this is the most obvious indicator if the lobe is correctly placed. This is made easiest by isolating each lobe when placing, by either muting within the automix, soloing in your processor or using Dante Virtual Soundcard to tap into a single lobe, all work a treat!
Tip: If using auto-position, ensure you check lobe height as this is key to accurate lobe plots within Designer. As a rule of thumb, we use 1.2m for seated participants and 1.5m for standing.
As well as all of this, you also have a small amount of auto-steering per lobe which will help improve performance even further for those talkers that move around whilst presenting.
With the correct design, deployment and commissioning, beam-forming microphones can perform incredibly well in even the largest of spaces, believe us, we’ve seen it! For any questions regarding microphones or our commissioning services, feel free to get in touch with the team.