I recall sitting in a movie theatre and watching Michael Corleone drop the gun that he had just used to “off” some dirty cops in The Godfather.  It’s the first time that I saw this done.

Michael Corleone about to drop his gun after he “offed” two dirty cops in The Goldfather

Since then there have been many runner-ups to that, with microphones and not guns:  JayZ at the Superbowl and President Obama during his last speech to the press club.  It shows finality – with attitude!

The audiologist side of me says, don’t do that.  It’s like folding back book pages in a book. This is not cool.

But part of me wants to be as cool as the President or Michael Corleone. Dropping a microphone gives instant street cred.

Well, in the olden days, it certainly wasn’t cool, especially with the piezo-electric microphones that were used back then.  It’s much more likely to just dent the microphone casing nowadays than cause any real damage to modern day microphones. The piezo-electric microphones use a crystal that bends and flexes whenever an acoustic signal impinges on it, thereby creating a current.  (Incidentally, they also work backwards; when an alternating current is applied to the crystal, it bends and flexes and can be used as a loudspeaker; albeit with different efficiencies.)

President Obama at his farewell speech to the Press Club. Photo courtesy of imgflip.com

If Michael Corleone (or his father The Don) had dropped a microphone, the odds are that the mechanism inside of it would have shattered and the microphone owners would not have been pleased.  But then again, if Michael Corleone or his father had dropped my microphone, I would have just smiled and slunk away into a dark alley.

In more modern times, hearing aid microphone technology has improved and we typically use either a dynamic microphone or an electret based capacitor microphone and both of these are less susceptible to be damaged by some well-meaning but street smart performer who wants to look cool.

Dynamic microphones do not require a power supply whereas the capacitor microphones do.  Other than that, at least for speech, dynamic microphones and capacitor microphones are virtually identical.  For music, capacitor microphones can be more useful, especially for percussive musical instruments.

In the next blog entry, dynamic and capacitor microphones will be compared and contrasted, and maybe we will find out why the XLR cable connector is called an XLR cable connector…

Almost every week I hear about a move in the field back to the olden days.  A few weeks ago, I heard (on NPR) about a move back towards 8 track cassette players and indeed I still have one in my car. 

Actually, that is true.  We were cleaning out my mother-in-law’s house and I came across a large 8 track tape player and put it in my trunk- I couldn’t see throwing it out.  So… although it is just sitting in my trunk, technically I do have an 8 track tape player in my car.

8 track tape player. Courtesy of YouTube.com.  Also identical to the one in my car!

There also seems to be a move back toward vinyl records and even cassettes although I really can’t be sure the 8 track is coming back.  Most of the movers in this area are self-confessed audiophiles.

Personally I have listened to both vinyl and mp3 files and they do sound different, but I can’t really say that one sounds better than the other.   Certainly the dynamic range and the frequency response of the vinyl record is poorer than that of a properly recorded mp3 file. This may make it sound warmer, but not necessarily better.

I am of the opinion that if we know precisely what is happening to the sound and we would like to “improve it”, we should be able to simulate that, sometimes with something as simple as an equalizer.  Ultimately all sound is just made up of pure tones whose levels are amplified, attenuated, and/or compressed by some well-defined algorithms or mechanical technologies.

Vinyl records have some inherent mechanical limitations (or perhaps these are strength?). Courtesy of deans golden collectibles

Vinyl records do have a mechanical limitation in that the playback stylus or needle can only oscillate so much given the limitations on its mass, stiffness, and how it is held in the playback mechanism.  The vinyl record itself has mechanical limitations in that the grooves are only so deep and this limits the dynamic range of the music.

There is a large body of sometimes-contradictory research that says that “less may be more”- perhaps a narrower bandwidth does sound better than a wider bandwidth, but there are so many other factors that it is difficult to nail down the final rule.

We see this problem when we compare dynamic versus balanced armature drivers in earphones and in-ear monitors.   There are some famous musicians and musical groups (e.g. U2 and Shania Twain) that prefer the “warmer sounding” but narrower dynamic range of a dynamic driver and others that prefer a balanced armature, wider bandwidth approach (e.g. Beatles).

There are of course, other differences in terms of distortion levels and types of distortion- again some prefer one and others prefer another approach.  If you attend any large sound engineering conference such as the Audio Engineering Society meeting, the exhibit hall has a row of tube screamer amplifiers where an old style tube is wired into the amplification system.  The tube imparts some interesting distortion characteristics that some find to be quite pleasing; others not as much.

Courtesy of Recordsredone.com

Even recording tapes of the 1960s and 1970s have their own features that some find to be quite pleasing.  The Ampex 456 tape has a “bump” in the low frequency range; the Scotch 250 has an enhanced high frequency range; and the Agfa 467 tape has an increased mid-frequency range.

There were aficionados of each of these tapes and many performing artists of the time would only market their music on a certain tape.

But then again, if you didn’t like the sound of the Ampex 456 tape you could just use an equalizer (or a tone control nob) to reduce the lower frequency sound energy slightly to compensate for the low frequency resonance.