In the thread about ISM Shortwave Transmitter both rlkocher and Artisan are experiencing a problem with audio distortion which is coming from a transmitter perhaps designed by someone who is "distortion deaf", as one of them said.
Since I am wandering away from the subject of the SW transmitter itself, I thought a thread on distortion might be worth posting.
There are people who seem oblivious to distortion. Case-in-point for me is a radio program available also as a podcast by a leading celebrity with excellent guests, but since she changed from one audio producer to another, her programs are the most distorted of all the podcasts on the internet. Terrible over-recording, under-recording, shattering sound break-up.
I wrote a few e-mails to the producer and politely mentioned the distortion, so he sent me a copy at a much higher kbps rate, perhaps 192kbps instead of 32kbps, and it was exactly as distorted.
I finally had to cancel my use of the show because the producer is either a well-meaning distortion-deaf person, or someone trying to ruin this woman's podcasts.
I have not written to her about it because I figure that if she doesn't notice the distortion than better to leave her be.
There actually are people who are distortion deaf. I have two examples for right now.
A client hired me to record her radio interviews, and I was playing back a session for her using a quality FM radio for monitoring. She was sitting right next to the radio and asked, "Can you turn it up?"
I pointed to the volume control and invited her to adjust it to her taste.
She turned the volume to maximum and the radio went into rasping blaring distortion, I thought the output transistors would explode, yet she sat there smiling and listening.
I gently turned the radio down to safe-loud, and asked, "Did you notice that was very distorted?"
She replied, "I'm deaf on one side and have trouble hearing."
The other example is a relative who invited me to watch a movie on the new flat screen tv, but the volume was cranked to absolute painful distortion, so I asked if it could be turned down. The answer was, "No. If I turn it down I won't be able to hear it."
I don't watch movies with that relative any more.
My Father had perforated ear drums and middle ear damage due to infection as a child and had difficulty hearing. In the 60s surgery became available to close the ear drums and rebuild the conductive bone system and he had the procedure which did not restore normal hearing but was done to prevent infection. He used hearing aids but they had to be turned to a loud volume. He never enjoyed music, live or recorded, possibly because all of his hearing was filtered through comparatively low quality electronics of the era.
The family suffered with high TV and radio volume with him and as a gift I gave him an AM/FM Walkman with decent headphones in the early 80's so he could listen to the baseball games on radio while viewing them on TV. Later, I tapped into the TV circuit so he could listen to the audio on headphones without subjecting the family to the high volume.
I remember him commenting that he had never heard clear sound before this and he began to enjoy music which was not filtered by the hearing aids.
Could it be that some people, for whatever reason, do not hear clear sound and therefore don't recognize distortion?
Just as with eyesight, hearing varies among people. My own situation is the opposite of my Father's in that I am very sensitive to pitch and distortion and was tested and shown to be in the 99th percentile for pitch and rhythm recognition. Until the advent of vastly improved amplification and recording technology I had been annoyed by distortion in reproduced sound. Even now, with excellent electronics, I can hear problems if the source is not up to par despite my age acquired hearing loss. I suppose either some people do not hear defects or, as was the case with my Father, have never heard clear sound and don't discriminate audio quality.
Neil
The destination of any radio broadcast is the ears of the audience, and it is just as important to learn a little bit about the subject as it is to know something about antennas.
The sound we hear is not digital, it is analog; but the ear, ultimately, is a biological device.
Everyone says: "Digital sound is the best." But the digital domain is only "in-between" sound that originates in the analog state, then finally gets transformed back to analog.
True "digital sound" would be like a sword-fight with chain saws.
Digital sound is a convenience. An easy way to store music and/or talk. If you are fortunate enough to own a good turntable & cartridge, you can enjoy the warm, rich sound of vinyl (which I greatly prefer over CD's).
This is only intended to stimulate some thought for fun but it could be that the sound system we humans have is digital and not analog. Sound propagates as longitudinal waves through the air where each air molecule presses on the next causing it to move. Since the molecules are discrete particles the sound wave is not continuous but is the summation of the motion of these air particles and thus is quantized since the particles are finite in size. This summation seems continuous since the particles are very small.
In our ears, the mechanical motion of sound in air is detected in the cochlea which contains tiny cilia (hairs) each tuned to a different frequency. Each cilia response to a particular frequency is a nerve signal which is either on or off with the strength of the sound being represented by the number of these on or off nerve signals created per unit time so in a sense the link from our ears to our brains is digital.
Something to ponder with our digital brain synapses.
Neil
There is a difference between analog and digital audio sources and some do prefer the vinyl sound but vinyl can include unwanted noise caused by scratches and dirt.
There is probably not much which can be done about scratches but maybe noise caused by dirt can be fixed. I have read about a few methods to clean vinyl records and ask if anyone has experience with this. The simplest is to wipe the record with a damp cloth.
Another suggestion is to run the record through the dishwasher with cold water and detergent but I doubt the label will emerge undamaged.
The most radical method I have read about is to coat the record with some casein based glue (wood glue or Elmer's glue), let it dry, and peel it off the record. The theory is that the glue will pick up junk from the grooves leaving them perfectly clean. Anyone ever tried this?
Neil
During a time when my best excuse was that I was "young" I happened to glue a fresh circular felt surface onto an aluminum turntable.
It was "airplane glue", the kind people inhaled to become permanently brain damaged. I truly think my own brain damage is from some other cause, as I often stood up under hardwood furniture and hit my head.
But airplane glue fumes wafted right through the felt cloth and totally deformed one side of "Themes from Horror Films", which I still have, with one good side.
Life has its regrets.
I still have my turntables and a stack of records.
I bought a nifty gadget for cleaning records about 40 years ago. Its called Vac-O-Rec.
You place the record in the slot. A rim-drive rubber shaft rotates the record. There are felt brushes that lightly rub both sides of the record while the units vacuum sucks air past the record to remove the dust.
In commercial radio, we used a spray bottle of plain water to heavilly soak an old record, right before we played it, or as it was being played. The dust and grit would float above the groove, where it couldn't be heard. It's amazing how much noise can be removed! We never dried the record at all until after we were done playing it, and even after a thorough wipe down all that noise would return to the record, and you'd have to wet it down again in order to play it again. But the reduction in noise was worth it. If you've never tried this, you must! Play 'em soaking wet!
Somebody could modify a turntable to become attached to water pipes and a drip catcher underneath everything.