The microphone placement playlist

Last week in music tech class, we talked about audio recording, and how the placement of microphones relative to the voices or instruments can shape the sound of a recording. Mics don’t just pick up the sound of the voice or instrument itself. They also pick up the sound of the voice or instrument bouncing off the walls, floor, and ceiling. Depending on where the mic is relative to the sound source, it might pick up more direct sound or more indirect sound. The specific blend tells the listener a lot about the environment that the sound was recorded in, and carries information about style and genre too. 

Here’s a highly simplified diagram of sound in an environment. The solid line represents direct sound, pressure waves going straight from the guitar into your ear. The dotted lines are indirect sound, pressure waves that bounce off the walls, floor and ceiling before reaching your ear.

In a recording, microphones are a stand-in for your ears, receiving pressure waves and converting them into electrical fluctuations. If the mic is close to the sound source, it will mostly pick up direct sound. If the mic is far away from the sound source, it will mostly pick up indirect sound. 

Before multitrack recording was invented in the 1950s, all recordings had to be live. You could use multiple microphones, but they all went to a single tape. The main way you could control the sound of the recording was by placing the mics relative to the performers. If it was a big ensemble like the Duke Ellington Orchestra, you wouldn’t be able to mic every instrument individually, so that meant mostly recording indirect sound. Ellington worked creatively around this restriction in “The Mooche”. The best version I have ever heard is on Duke Ellington & His World Famous Orchestra (1946-1947), a set of live performances from the radio during a period when the band was killing. Sadly, that one isn’t online anywhere, but fortunately there is a filmed version. Listen at 1:28.

One clarinetist is up front, close to the mic, playing quietly, and you are hearing a lot of his direct sound. The other clarinetist is back in the reed section, further from the mic, playing at normal volume, and you are hearing him mostly indirectly. The sonic contrast matches the contrast in their playing styles.

Miles Davis was another creative user of the microphone. His iconic recording of “Round Midnight” begins with his muted trumpet, played quietly about a foot from the microphone. Then, at 2:45, he steps back from the mic, removes the mute, and plays at full volume. You can hear much more of the room in his open sound.

Classical recordings have always tried to recreate the sound of the concert hall, so engineers place the mics at the same distance from the performers as the audience would be. In this recording of Maria Callas singing “Habanera” from Carmen, the mic is far above or in front of her, and not visible in the frame.

It sounds very different when you sing up close to the mic. Just about all current pop music is close-miked, so it doesn’t sound very remarkable. But in the early days of this practice, it must have sounded shockingly intimate. Listen to Ella Fitzgerald and Louis Armstrong sing “They Can’t Take That Away From Me” – they are very close to the mic, and singing quietly. They are practically whispering straight into your ear. You can hear Armstrong clear his throat at 1:22, and you can sense every bit of his throat anatomy after he starts singing.

Like classical voice recordings, classical piano recordings similarly aim to capture the room more than the direct sound of the instrument. Here’s Arthur Rubinstein playing Chopin’s Nocturne No.1, Op.9. I don’t know whether this was recorded in a concert hall or a studio, but if it was a studio, they took pains to make it sound like a concert hall.

When rock bands use piano onstage, they typically mic them very close out of necessity,  because they don’t want the piano mics picking up the drums, guitar amps and so on. The typical strategy is to put the mics inside the piano and shut the lid. Rock pianists came to like the clear, bright sound this produces, and they started doing it in the studio. My favorite example is “Honky Cat” by Elton John. 

Here’s a recording of classical strings, the Guarneri Quartet playing Bach’s Art of Fugue. You know the drill: the performers are onstage (or “onstage”) and the mic is in the audience (or “in the audience”).

Here are some close-miked strings, from “Eleanor Rigby” by the Beatles. This would have sounded extremely harsh and dry to listeners at the time.

Here’s how it sounds when you close-mic everything in as dead an acoustic environment as possible. This song occupies no particular physical reality; it sort of exists in dreams… get it?

It can be interesting to combine different mic techniques to give the listener contradictory spatial information. In Joni Mitchell’s song “Blue”, her voice is close-miked as usual for a rock or pop singer, but her piano is miked classical-style, picking up lots of indirect room sound.

You can also combine mic placement with signal processing to get some truly strange and interesting sounds, like the drums in “When the Levee Breaks” by Led Zeppelin. But that’s a different week of class.