Feature: In-Ear Monitoring

In-ear monitoring is approaching its 35th year in the business. Jim Evans tunes in to assess how the market has moved forward, and what to look out for when buying a system.

Wireless technology has pretty much taken over the world of communications and the live music sector is no exception. Wireless microphone systems have become the norm and, as evidenced at last month’s Winter NAMM in California, remote wireless mixers are gaining in number and popularity. And in-ear monitoring, having kicked the wedge monitor into the long grass, is now favoured by acts across the spectrum – from the smallest pub combos to the mega stadium bands.

The advantages of IEM and the history of their development have been well chronicled. In this respect, readers are warmly recommended the paper, In Ear Monitors A Brief History, written by Sensorcom’s Richard Frankson and sound engineer/IEM pioneer Chrys Lindop.

In-ear monitoring provides a multitude of benefits including the ability to hear vocals and instruments in the mix at levels the artist would like. IEM will also help singers pitch accurately, with the system also doubling as a hearing protection device. For monitor engineers IEMs have been a revolution both in the complexity of the mix and the fight with artists over levels and the constant problem of acoustic feedback.

In fact, monitor mixing has become considerably more complex as the mix has to assemble all instruments as well as ambient microphones to generate the live feel for the performers, which would otherwise be absent as their ears are occluded. And for the concert-goer the benefits include significantly improved sound as the floor monitors and side-fills, often at high audio levels, were picked up by the stage microphones and are now used as low level backups or somewhere to put feet and playlists. In the consumer market IEM earphones are part of the iPod revolution where it is possible to block out sound and create your own listening space in substantially better quality than regular non-occluding earbuds aka: Walkman-style earphones.

Technological advances

Mick Shepherd, co-founder of North London-based radio microphone and earphone specialist Hand Held Audio, says: “There have been advances and improvements [in IEM technology] but the central technology remains the same. A number of systems now use diversity body pack receivers, such as the Shure PSM1000 and AKG IVM4500, while Sennheiser has an adaptive diversity technology where the earphone cable neatly doubles as the second antenna. The lithium-ion rechargeable battery advances are appearing in some systems too.”

“RF technology in general has advanced greatly over the past decade,” suggests Tuomo Tolonen, manager – pro audio group, Shure Distribution UK. “Ongoing changes to UHF spectrum availability has resulted in some outstanding products and IEMs are no exception. Use of wireless systems has increased and they need to operate reliably in ever-harsher RF environments. As the IEM receiver is typically on stage they can be prone to RF noise from sources like LED walls. PSM1000 is the only real diversity system out there as it operates on two identical antennas and this makes a very noticeable difference in these kinds of environments. Another improvement over the last few years has been audio quality with advances in dynamic range, lower self-noise and frequency response.”

Sensorcom’s Richard Frankson notes: “IEMs started by stripping down Walkman earphones and building them into custom acrylic earshells, which was fine, but when it came to fitting smaller ears it became a problem. Typically the drivers were 15mm in diameter so it could be difficult to make the IEMs as small as the client would like. Manufacturers started to look at hearing aid components, balanced armature drivers, and found that with correct matching they would give acceptable results. The manufacturers of these components have since made drivers especially for the IEM market.

“As IEMs evolved then multiple driver sets were employed to give better frequency coverage. Typically today in the professional markets dual or triple drivers have become the norm, but in the consumer esoteric markets up to eight driver combinations can be found. However, short of costing a phenomenal amount of money and producing very high sound pressure levels we don’t really see the acoustic advantage.”

Rob Piddington has been involved with in-ear technology since the early days and is currently working as a consultant with Sensorcom whose IEMs are marketed under the ProGuard brand. He comments: “The basics of IEM technology have remained the same over a number of years, originally using dynamic and gradually changing to moving armature drivers. Moving armature drivers were originally designed to be used with hearing aids. They are used extensively in most of the leading IEM products on the market today; they are much smaller and compact in physical size than their dynamic cousins. The big advantage is they can be tuned and utilised in a specific frequency band, multiple drivers tuned then coupled using a crossover network.”

Mick Shepherd (left) and Nick Bruce-Smith of Hand Held Audio.

US-based Sensaphonics focuses on hearing health, using its advanced technology both for accurate, comfortable stage monitoring, but also as a platform to provide hearing solutions for musicians and engineers who otherwise cannot work due to various impairments. Company founder Dr Michael Santucci observes: “The core technologies of in-ear monitoring have changed very little in the past decade, as indicated by the fact that most new flagship models are notable only for adding more drivers to existing designs. Consumer companies are now dabbling in wireless headphone designs, but due to latency issues and bandwidth limitations, that technology remains impractical for the professional musician.”

Santucci further suggests: “The biggest technical advance in recent years for us is the Sensaphonics 3D Active Ambient, which eliminates the need for stage mics by providing full-range, controllable ambience to the monitor mix with accurate 3D dimensionality, while maintaining the isolation needed to realise the hearing health benefits of in-ear monitoring.”

Choosing a system

“High fidelity is a given, and is delivered both by us and most of our competitors,” says Santucci. “But then comes the hard part – high isolation, consistent seal and long-wearing comfort.

“The biggest mistake you can make is choosing an IEM based on driver count. Our clients, including some of the most demanding artists in the world, will confirm that a properly designed IEM can deliver full fidelity with just two or three drivers, preferably with only one crossover to minimise phase distortion. Excessive drivers are certainly louder, usually more expensive, and provide more parts that can break down.

“Sensaphonics IEMs are designed for deep insertion – past the second bend of the ear canal – and are made from flexible medical-grade silicone, which has been proven to provide more isolation than other materials. Because the ear canal changes shape with facial movement, silicone earpieces move with them, maintaining the seal. An acrylic earphone that ‘pops right in’ may be convenient, but is poorly fitted and will not reliably provide the needed isolation and seal on stage.

“This is important because losing the seal results in a huge loss of bass response (often the cause of artists pulling one earphone out). Hard acrylic cannot reliably maintain its seal under stage conditions, which is one reason so many manufacturers keep adding more drivers. Beyond the marketing advantages, in my view, it’s also an attempt to compensate for a design flaw.

“Soft silicone also provides a more comfortable IEM experience, which is very important for musicians and sound engineers who regularly deal with long rehearsals and performances.”

Mick Shepherd advises against buying an IEM system that operates on a frequency above 694mHz as there’s a very good chance that availability in that spectrum for radio mic and in-ear users will disappear within the next five years or so. “Look for a system with a solid body pack as they often get dropped. A good wide switching window to maximise frequency choice is advisable for European and worldwide use,” he says. “The ability to accept two mono inputs at the transmitter and mix them at the pack is very useful – it allows you to get two discreet mixes from one transmitter and two packs.

“If you don’t move around in performance (eg, most drummers) look at a hardwire system – much less expensive. Again look for the facility to mix two mono inputs – you can run a click track separately this way.”

Tolonen cautions: “Ensure you get the right system for your application. If you are a global touring act, the tuning bandwidth can be a factor in making sure you have enough of a ‘window’ to get all your channels programmed as spectrum will change from country to country.”

Is going cheap a mistake?

“Definitely,” declares Shepherd. “We wouldn’t have cheap systems in our hire stock and on the odd occasion that we’ve sold them we’ve had nothing but trouble. If you have a limited budget it’s worth looking for ‘pre-owned’ decent quality systems in good condition.

“It depends what you consider cheap,” says Tolonen. “The bottom line is that your IEM system is what you listen to when you are performing. It needs to sound good, needs to have solid RF performance and also have a feature set that suits your requirements. I’ve heard on several occasions that a good IEM system can make you perform better so it’s critical you get the right one for the job.”

Frankson adds: “Even cheap monitors will produce better monitoring than floor monitors as acoustic feedback is not a concern. But like most things in life you will very much get what you pay for and with well-built IEMs with MA drivers the sound will create a sense of precision and detail which will make them more pleasant to listen to.”

“Sound is very subjective and you like what you like – the real answer is finding the right balance in quality and the sound you desire rather than cost,” says Piddington, while Santucci concludes: “For professional musicians on stage, there is no substitute for quality.”

How important is customisation?

Richard Frankson: “Customisation has two functions. It forms an earplug to exclude external sound and allows for the IEMs to be made discrete. They will be very comfortable too as being custom there are no pressure points that a generic one will create. And it also guarantees that no one else can use them.”

Mick Shepherd: “Custom ear monitors are a really good idea… but you have to have the budget. Not only will custom ears never fall out, but also if they’re from any of the leading manufacturers they will sound fantastic – guaranteed. Having said that many people get a very good result from less expensive universal-fit earphones – it’s crucial to find the eartip or foam that gives a snug, comfortable fit to your ear canal. If it does that the sound will follow.”

Tuomo Tolonen: “Custom moulds are popular but on the other hand are expensive and difficult to replace on the field. The right universal earpieces can give you outstanding audio performance, with the SE846 (quad driver) earpieces being a great example. They include a patent-pending low pass filter design that gives the 846s an outstanding low frequency performance. The rest of the frequency response is also customisable with detachable filters.”

Martin Fischer: “If you want to have the utmost in audio quality you should invest in customised ear moulds. In many cases, however, generic ear moulds will do a good job too. This decision will depend on your budget – professionally made ear moulds can be quite expensive.”

Michael Santucci: “In our view, custom fit is essential to realising the potential of the IEM concept. In fact, Sensaphonics makes only custom-fit products for this very reason. There is obviously a great market for so-called universal-fit products, but the benefits of custom fit are a core requirement for music professionals.”

The Sennheiser connection

Sennheiser was among the first companies to launch wireless in-ear monitoring systems. After a period of time when the company supplied individually manufactured systems to artists, Sennheiser eventually launched its first professional in-ear monitoring series in 1996. These systems largely corresponded to the current state of the art.

“However, since then we have seen quite a few improvements regarding the convenience of IEM systems, and product features have been continually refined to make the work of monitoring engineers easier,” says Martin Fischer, product manager, Live Performance ?and Music.

“To further improve transmission reliability, for example, Sennheiser introduced diversity reception with its evolution wireless 300 IEM G3 systems and the 2000 IEM Series in 2009. Or take the Engineer Mode, which was launched a little later and enables the monitor engineer to tune into the beltpacks of the artists and listen to their monitoring signals.

“Then on the software side and via the Wireless Systems Manager Software, we created a remotely controllable RF co-ordination tool and included adjustable audio settings for IEM systems. Thus, frequency co-ordination of multiple monitoring systems has become a lot easier, while the audio settings ensure that artists get exactly the kind of audio reproduction they need and want.”

On the viability of digital IEM systems, Fischer states: “Quite a few people are asking about digital IEM systems these days but such systems are currently not feasible because digital systems always involve a certain amount of latency due to A-D conversion and the codec used.

“The requirements on IEMs regarding latency are quite high – if the signals travel too slowly, the IEM audio signal and the bone-conducted audio signal will interfere, and frequencies will cancel each other out. As a general rule, the audio signal should not travel more than five milliseconds across the entire signal chain, (ie from the microphone to the monitor desk and back again to the artist.) At any point in this chain, any digital equipment will add latency to the signal.”

Fischer suggests: “The most important criterion is transmission reliability. An artist relies on the monitoring, and a signal loss would be critical. Audio quality is also high up on the list, and most often a stereo signal is preferred over a mono one.

“Also, many users ask for high levels, which can be attributed to the fact that many people only switch from wedges to wireless monitoring when they notice that their hearing has already deteriorated.

“And last but not least, frequency flexibility is becoming increasingly important these days. Frequency-agile systems allow users to select alternative frequencies should any given frequency band be congested.”

Main picture: On stage with Shure’s PSM300 personal monitor system.