Occasionally, when I see a video crew working on the streets of New York City, I take notice when no one is wearing headphones. I like to innocently ask: how do you know your sound is good? The answer is enviably: “I see the VU meter moving.”
Instantly, I know this an amateur video crew. They are not monitoring sound at all. It is hit or miss whether they are getting any usable audio.
Headphones are essential equipment for any audio or video application. Using them on location is the only way to ensure problem-free audio. It is amazing to me that so many video crews don’t seem to know this!
One of our oldest audio technologies, headphones were originally created to free up a person’s hands when using a telephone. By the 1890s, the first headphones were made by a British company called Electrophone. It allowed customers to connect via telephone line into live feeds of performances at theaters and opera houses across London.
The more recent boom in portable audio drove today’s popularity in headphone listening. There is a myriad of choices of headphones on the market and specific types designed for every application. Choosing the right model for the job is important, not only for sonic quality but wearer comfort.
Avoid cheap consumer headphones and wireless Bluetooth models for professional applications. Consumer headphones may by colored and not accurate enough. Bluetooth technology, though touted as reliable, often has flaky, undependable connections. Some might disagree, but I don’t think Bluetooth is ready for monitoring critical pro audio.
Most major headphone manufacturers make models in three types: open, semi-open and closed-back designs Each has a unique purpose.
Open-back headphones offer the least isolation, which means the wearer hears nearby environmental sounds while using the headphones. These phones allow air and sound to freely move around the ear. This movement allows for sound clarity and a soundstage that is deep and open.
Open-back phones offer accurate, airy sound and are great for music listening in quiet rooms. The trade-off is distraction from ambient sounds. The lack of air containment can also remove some of the visceral boom from the bass.
These are not the best headphones for location sound monitoring. And, if the user is doing a podcast, radio broadcast or voice-over work, sounds can easily bleed into the microphone, causing feedback.
Closed-back headphones, on the other hand, isolate the listener from the background. Bass and lower frequencies are enhanced. This design is best when used on location or when distracting sounds are all around. They are the best type for monitoring video sound and recording audio in the field.
Closed-back headphones, however, are not as accurate as open-back models. Their closed backs restrict the flow of air and sound. They are designed to allow the user to concentrate on the sound being monitored without outside distractions.
However, the same containment that isolates sound also traps the sound, meaning the audio can become colored from rebounding soundwaves. This can diminish overall clarity of the audio.
A third type are semi-closed headphones. These are halfway between open and closed-back headphones. This is the most difficult choice, since it clearly comes down to what works best in a specific application.
A rule of thumb to remember is when using headphones at a noisy location or close to a microphone, closed-back headphones are the best choice. When working in a quiet studio, edit bay or critically listening to music, open-back is best. The use of semi-closed headphones should be decided on a case-by-case basis.
Another consideration in choosing headphones is the impedance level. Headphone impedance is usually rated between eight and 600 ohms, with the most common consumer models being about 32 ohms. To ensure the highest audio quality, the headphones must match the source providing the signal.
Generally, low impedance headphones are below 50 ohms and are designed to work properly with portable consumer electronic devices, such as smartphones and music players. Conversely, high impedance headphones are usually 50 ohms or higher. They require more powerful amplification and, in some cases, dedicated outboard headphone amplifiers.
Comfort is also essential, especially if the user is wearing headsets for long periods of time. Too snug headphones squeeze the head and can exert very uncomfortable pressure to the wearer.
For comfort considerations, there are three types: over-ear, on-ear and in-ear headphones. Over-ear phones surround the entire ear; while on-ear models rest on top of the ears. In-ear monitors sit in the ear and seal the walls of the ear canal.
The larger cups on over-ear headphones means they can hold larger drivers that generate deeper, cleaner bass. Over-ear headphones tend to be bulky and offer better isolation. On-ear phones are typically smaller and offer comfort and portability. In-ear are the most portable, and have great capacity for sound isolation.
Finally, consider the types of drivers. Today’s headphones have dynamic, planar magnetic or electrostatic drivers. The most common type for general sound monitoring is dynamic.
Dynamic headphones work by sending a signal through a coil of ultra-thin wire. This creates a magnetic field around the coil. The coil is moved rapidly back and forth by a magnet, which in turn makes the speaker diaphragm move. This movement compresses and decompresses the air to create sound.
Planar magnetic drivers also use magnetization to move a diaphragm back and forth. However, with this type, the charged metal is spread evenly across an ultra-thin film. It moves back and forth between two arrays of magnets to compress and decompress air to make sound.
Planar magnetic headphones offer reduced distortion and excellent sound clarity, but they usually require an outboard headphone amplifier to operate.
Finally, electrostatic driver headphones don’t use magnetism at all to move a diaphragm. Instead, a piece of electronically charged material — only microns-thick — moves itself. This type is typically a money-is-no-object purchase designed for audiophiles.
There are a huge variety of pro headphones on the market. Since they are so personal, it is best to try them on and listen before a purchase. What’s comfortable for one person may not be for another.
Finding and using the right headphones is an essential part of monitoring sound — either on location or in a studio.