SIGNAL to NOISE RATIO
by Doug Booth
Signal to noise ratio is what the audio engineers called it in the ancient days of analog sound recording and reproduction. A good example of low signal to noise ratio is the 78 rpm breakable phonograph discs folks played in the 1930s and 40s. After a few dozen plays, the steel needle had worn the musical signal out of the grooves in the shellac disc, and the molecular structure of the base material was being reproduced about as loudly as the music. That composed about a one-to-one ratio.
Many systems for recording/reproduction of sound followed: Wire Recording, Tape Recording, Film Recording, Microgroove (33 & 45 rpm discs) on vinyl before the advent of Digital Recording. Each analog step provided improved signal-to-noise ratio for less background noise. Also, each was an inherently noisy way to reproduce high-pitched sounds.
So, how did they get their S/N ratio so much better than 78s? A tone-shaping circuit in the recording device caused the high-pitched sounds to be recorded at a much, much higher volume than the mid-range and bass sounds. Conversely, the player for such tapes and discs contained a circuit which reversed this process; so the reproduced music had the proper tonal balance, but the excessively loud high notes and the inherent high-pitched noise were removed. Voila! The birth of Hi-Fi!
That was all well and good for the recording industry, but how about my reproducing devices called ears? I’d say their signal-to-noise ratio is rather low compared to most folks. In fact, I don’t think I have ever heard complete silence. Ever since I can remember, a faint high-pitched raspy sound somewhat similar to cicadas has been in my brain. It is not monotonous but is slowly modulated as though some insects quit and some were added to the chorus. When I was very young, I thought everyone heard this, but eventually discovered that most didn’t. I usually ignore the condition unless my surroundings are very quiet.
Twenty-four years ago, my wife Grace suggested that I should get my hearing checked because I was asking her to repeat something she told me. My GP (PCPs had not yet come into political correctness) referred me to an ENT doctor in Slidell. His comment after testing me was, “I can’t do anything for your tinnitus, but you have very good hearing for a sixty-year-old.” Oh, well, I suppose my hearing is now slowly going away, because I need to cup my hand sometimes behind my ear when Grace is reading to me next to me. Of course, she is speaking toward the book, not facing me.
In addition to the noise in my head, music is nearly always present. When my feet hit the floor in the morning, a song always springs into my mind. It may be “How Great Thou Art” or “Zippity Doo Dah.” I never know what to expect. That will run around in my head with me trying to dredge up the correct lyrics from my cobwebbed cranium. Grace will usually be listening to TV or be playing a CD in the kitchen when I report for breakfast. Whatever music she provides may sidetrack my waking music and take over for a while in my background.
I spent 35 years as an engineer or Chief in several radio stations and one TV station in New Orleans. If anyone has heard a variety of music, it is I. Some music I’ve heard, I rejected. To my sensibilities, it was noise. But, I heard it and it is stuck in my memory. Sometimes, objectionable music plays in my head and becomes so hard to suppress that I have to return to a half-hour session with loud music of my roots—Classical—in order to purge it. Usually, I can do it with one of my six or so favorites just waiting to be called up.
I have found, when trying to calm my thoughts for sleep, the most effective method is “a turn to the right, a little white light, will lead you to my blue heaven.” (My Blue Heaven, Gene Austin, 1927) Yes, I know that is starting in the middle of a musical phrase, but that’s the way it plays for me.
I hope your music always plays much louder than the noise, be it around you or inside.