Thursday, November 02, 2006

Pop filters, screens and pantyhose


I have to admit that I dislike pop screens.

A pop screen is a filter that is placed between a sound source, usually a person's mouth, and a microphone.

The purpose of a pop screen or filter is to prevent or reduce plosive sounds produced during speech, which can ruin an otherwise decent vocal recording.

If you listen to college radio (and some pro stations too) and have a subwoofer, you are already too familiar with the unpleasantness of Ps popping. It's just bad mic technique, plain and simple. Most FM stations use RE20 dynamics that incorporate a very agressive pop filter in the housing. They are everwhere. Notice the "blocky" sound you get from that as you drive home today. It's not all the awful sound of the Optimod.

Stage performances and popular culture have made "close micing" the accepted practice. Close mic technique does have its advantages, such as less need for a lot of amplifier gain, and therefore reduced feedback. Close mic technique on voice brings up the bass which is often absent in the sound emanating from the mouth. Bass in a professional singer's voice tends to radiate from the chest.

So the stage performer eventually makes it over to the recording studio, and the sound she is used to is from a stage vocal mic, like some dynamic with a ball on it containing a lot of plosive filtering. In the studio, things are different. Open up any C12 and look at all the dried saliva spattered on the capsule. Gross. I am talking about the usual singer here, not the trained opera voice. So a spit screen is probably a better name for a pop filter.

The studio engineer sets up a pop filter, the usual thing to do. Like I said, it has its advantages. It creates an acoustic resistance which is frequency dependent. This cuts the bass. Some people say it stops the wind. What's the difference? Another advantage of the pop filter is that it provides a target for the singer, and helps maintain the singer's position as a result. This is important, as a microphone, depending on its characteristics, usually has a sweet spot where the balance of tone and articulation sound best.

But pop filters have a downside. Regardless of the material, the geometry and its placement, the pop filter imparts its own sound on the vocal, which may be subtle, or not so subtle.

Microphones are sometimes thought of as being analogous the the ear. While this is not accurate, let's let the analogy stand and imagine listening to someone singing into your ear at a distance of only three inches. If you like the sounds of tonsils rattling, then go for it. Because of this long lasting cultural presentation of the human singing voice, almost everyone has become accustomed to that sound.

I don't like it and I suspect others also do not. This is driving the sale of a lot of vocal mics which is good for business. But I prefer to hear you speak or sing from a safe distance where I can appreciate the natural bass in your voice as it radiates from your face and chest, while avoiding a shower.

P - popping is simply bad technique. Singers should demand recording situations that don't exacerbate plosives. The use of a close mic technique has to be done carefully to avoid plosives and excessive palate and tonsil action. Young female singers in particular often have a lot of noise coming from the vocal chords that sounds like a kazoo, possibly due to the suppleness of their larynx tissue, and the efficiency of their voices, which need little air. Microphone Tizz makes it even worse. You hear that buzz saw voice all the time and it seems to go away as the female voice matures, which is a relief by itself.

Using a microphone that has a pleasant balance of tonal characteristics without needing to be so close to the singer's lips is a big help in all this.

Ribbon mics have a bigger sweet spot that extends a greater distance from the mic. This "reach" is also prized for hall and ambient recordings too. Professional singers, I mean the real pros, and the opera singers and stage vocalists who have to project their voices well already know this and you can find plenty of pictures of these artists at work, often with the mic a foot away.

A pop filter will not cure bad vocal technique. It will get the singer to back off, at least, but at the expense of bass, which is why the mouth was so close to the mic to begin with. A better way is to educate singers, have them learn good recording technique and how it is different from stage technique, listen to their voices at a bit of a distance to hear if there is any worthwhile chest in there. This will reduce plosives, palate clicks, gurgles, get rid of that "blocky" character, and keep your mics dry too.

3 comments:

Anonymous said...

this is an excellent summary of what happens from being too close! I bet theres crap in most mikes from spit

Anonymous said...

The reach you mention is just the area where the mic sounds best. It may be that the proximity effect is more pronounced, so the singer can back off and still sound "close" and maintain some bass.

Anonymous said...

The terrible vocals we hear are nothing but breath sounds because the singers cannot sing and the engineers don't know what to do. TN