Re: [Elecraft] PsychoAcoustics and Delay
On Sat, 1 Sep 2012, Jim Brown wrote: > A common real world example is a "star" singing the Anthem at home > plate, with an acoustic delay of 120-150 msec through the sound system > to the singer's ears. The solution is simple -- we give the singer > undelayed sound from his/her mic into headphones or a big monitor > speaker directly in front of them. The first time I was preparing to sing the national anthem for a large stadium (around 1990), my vocal coach simply echoed me so I could get used to it :). I still deal with it from time to time on the phone, where it really drives me nuts, but sometimes you just have to live with it. -kb7psg __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] PsychoAcoustics and Delay
On 9/2/2012 9:51 AM, Fred Jensen wrote: > Somehow, we managed to > key the transmitters multiple miles away with no noticeable delay. I > never got to the TX site so I don't know how they did it. A few years ago I visited both TX and RX sites for KPH, the coast station north of San Francisco, along with W3DQ, K3NA, and W0YK. The sites were something on the order of 20 miles apart, and the connection was an ordinary telephone line, everything analog, so no delay. The two sites could operate simultaneously on as many frequencies as they had operating positions. CW was simply translated to audio tones, a different frequency for each transmitter, and the output of tone decoders was amplified, rectified, and used to drive relays that keyed the TX. The line was (and still is) a dedicated line, so it does not go through the telephone switching network, so the only delay is the speed of light over that 20-30 miles plus the relay pull-in time. I don't recall how they said the operators were monitoring their own keying. K3NA had a new 2nd Class Telegraph license, so he operated a bit and got it endorsed. The rest of us watched. KPH is maintained by volunteers and is available for tours at scheduled times. It's well worth the time. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] PsychoAcoustics and Delay
On 9/1/2012 10:43 PM, Joe Subich, W4TV wrote: > Empirically the issue starts to become noticeable when the delay is > more than an element (dit/dah) and certainly becomes critical when > the delay is a substantial part of a letter. Yep, actually one dit time delay [or even close to it] is really annoying. The coastal marine stations in the 50's supplied sidetone while sending. I don't know where or how ours was generated, but it had a perceptible delay at 18 WPM [our "speed limit" when in traffic]. Since we had multiple receivers at each position, everyone got their sidetone by listening to our transmitted signal. Somehow, we managed to key the transmitters multiple miles away with no noticeable delay. I never got to the TX site so I don't know how they did it. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] PsychoAcoustics and Delay
Back in the 70s I had a three head reel to reel tape recorder. The separate record and playback heads allowed you to monitor what you'd just put on the tape, but a fraction of a second later. We discovered that we could have great fun with this ... put headphones on the victim, turned up fairly loud, and challenge him to recite something simple into the microphone such as the nursery rhyme "Mary Had A Little Lamb". Of course, no one could do it and the sputtering and looks of astonishment were hilarious. This works even better after a few beers. 73- Nick, WA5BDU __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] PsychoAcoustics and Delay
Hi George, Great to hear from you. Henry was mondo cool. A google search will turn up lots of interesting stuff. For the last couple of decades of his life he was the chief scientist for our country, founding director of the Smithsonian. The entire US government closed down the day he died and again for his funeral. I learned a lot about him when I did the research to cite him has a reference for an AES paper I was writing on stereo soud reinforcement around 2000, and invited an historian who concentrated on his work to speak to our AES section soon after. One of the things he was asked to weigh in on had to do with the physics of propagation of sound from foghorns. Big deal back then, there were multiple theories advanced, instrumentation to resolve the issue would not exist for at least 100 years, and he publicly put his money on the right horse. His work on the perception of sound and delay that formed the basis of stereo was published in 1850, and it was quite solid. There are multiple volumes of his scientific writing. I found them in the Northwestern University library. 73, Jim K9YC On 9/1/2012 9:38 PM, gdaug...@stanford.edu wrote: > Hi Jim, > >> One of the earliest scientists was >> Joseph Henry, inventor of voltmeters and motors, whose name is on >> the unit of inductance. > We measure inductance in "Josephs"? 8-) > > Sorry... that's one of my favorite word games. > > 73, > > George T Daughters, K6GT > CU in the California QSO Party (CQP) > October 6-7, 2012 > > > > - > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.2179 / Virus Database: 2437/5104 - Release Date: 07/01/12 > Internal Virus Database is out of date. > > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] PsychoAcoustics and Delay
> I don't know of any studies relating to delays and our ability to > send CW. Empirically the issue starts to become noticeable when the delay is more than an element (dit/dah) and certainly becomes critical when the delay is a substantial part of a letter. Just like the "soloist" and the National Anthem, the solution is to provide undelayed sidetone from the keyer rather than an off air monitor or RF derived sidetone. BTW, another place acoustic/DSP delays have become an issue is with live TV news. In the old days we used off-air analog signals or analog cell-phones for "IFB" (interruptable fold back) but with the advent of digital cellular systems and digital broadcasting, the delays are well in excess of the "magical" 150 - 200 ms threshold. For TV applications, the solution is to provide "mix minus" - that is the program feed *without* the reporter's own voice - so the reporter can interact normally with other participants. 73, ... Joe, W4TV On 9/1/2012 11:57 PM, Jim Brown wrote: > On 9/1/2012 5:58 PM, Bill Frantz wrote: >> Thanks for telling us about this "feature". > > Psychoacoustics is the study of the human perception of sound, and its > practitioners are a part of the Acoustical Society of America, of which > I am a member. The discipline is quite well developed, and what these > folks had learned as early as 1850 formed the basis of modern stereo > sound recording and reproduction. One of the earliest scientists was > Joseph Henry, inventor of voltmeters and motors, whose name is on the > unit of inductance. > > Sound system professionals have had to deal with electrical delay > resulting from digital signal processing (called "latency") since the > early '90s, when DSP came into widespread use in large sound systems, > and with acoustic delay that results from "time of flight" of sound from > live musicians on stage and big loudspeaker systems at considerable > distance (and height) from the musicians. Indeed, managing these delays > is a critical part of sound system design, especially in large spaces > and venues. > > When listening to a reproduction of our own voice, the human ear/brain > can tolerate delays up to about 60msec, but begins having fatigue with > much more than about 50 msec, and begins having serious trouble speaking > with a delay more than about 80-90 msec. As a pro audio engineer doing > a LOT of live sound, I've seen VERY experienced announcers turn to silly > putty with 100 msec. Musicians start having issues with tempo with > delays much more than 30-40 msec, which is why stage monitors have to be > so bloody loud! > > A common real world example is a "star" singing the Anthem at home > plate, with an acoustic delay of 120-150 msec through the sound system > to the singer's ears. The solution is simple -- we give the singer > undelayed sound from his/her mic into headphones or a big monitor > speaker directly in front of them. > > I don't know of any studies relating to delays and our ability to send CW. > > 73, Jim K9YC > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] PsychoAcoustics and Delay
Back in the "old days" many of us used no sidetone at all. We just listened to the clatter of our straight keys. In High School I could chat with my fellow hams in class with gentle taps of a pencil on the desktop. But I agree, I needed sidetone when I switched to a keyer. Funny, it was supposed to make sending simpler, not more complicated ;-) 73, Ron AC7AC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] PsychoAcoustics and Delay
On 9/1/2012 5:58 PM, Bill Frantz wrote: > Thanks for telling us about this "feature". Psychoacoustics is the study of the human perception of sound, and its practitioners are a part of the Acoustical Society of America, of which I am a member. The discipline is quite well developed, and what these folks had learned as early as 1850 formed the basis of modern stereo sound recording and reproduction. One of the earliest scientists was Joseph Henry, inventor of voltmeters and motors, whose name is on the unit of inductance. Sound system professionals have had to deal with electrical delay resulting from digital signal processing (called "latency") since the early '90s, when DSP came into widespread use in large sound systems, and with acoustic delay that results from "time of flight" of sound from live musicians on stage and big loudspeaker systems at considerable distance (and height) from the musicians. Indeed, managing these delays is a critical part of sound system design, especially in large spaces and venues. When listening to a reproduction of our own voice, the human ear/brain can tolerate delays up to about 60msec, but begins having fatigue with much more than about 50 msec, and begins having serious trouble speaking with a delay more than about 80-90 msec. As a pro audio engineer doing a LOT of live sound, I've seen VERY experienced announcers turn to silly putty with 100 msec. Musicians start having issues with tempo with delays much more than 30-40 msec, which is why stage monitors have to be so bloody loud! A common real world example is a "star" singing the Anthem at home plate, with an acoustic delay of 120-150 msec through the sound system to the singer's ears. The solution is simple -- we give the singer undelayed sound from his/her mic into headphones or a big monitor speaker directly in front of them. I don't know of any studies relating to delays and our ability to send CW. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
