| Page 1 of 2 | 1 | 2 |
|
|
Sensifivity of 2000-ohm Headphones
I am writing a program involving an antenna plus two coupled tuned circuits
plus a matched simple receiver. I would like to know, crudely, the audio power input level to 2000-ohm, iron diaphragm headphones for a nice, comfortable, not too difficult listening level. Such as when the phones are used on a crystal and cat's whisker radio receiver. Such headphones are more sensitive than modern 8-ohm varieties. I have a pair of 2000-ohm headphones but unfortunately no means of measuring power or voltage input. Just the number of micro-watts please. At what low power input level does speech or music just BEGIN to fade out to a person of normal hearing? Any ideas? I could take the average of a few replies. ---- Reg, G4FGQ |
On Thu, 1 Jul 2004 19:43:02 +0000 (UTC), "Reg Edwards"
wrote: I am writing a program involving an antenna plus two coupled tuned circuits plus a matched simple receiver. I would like to know, crudely, the audio power input level to 2000-ohm, iron diaphragm headphones for a nice, comfortable, not too difficult listening level. Such as when the phones are used on a crystal and cat's whisker radio receiver. Odd, I was just corresponding over this very matter recently. Such headphones are more sensitive than modern 8-ohm varieties. I have a pair of 2000-ohm headphones but unfortunately no means of measuring power or voltage input. Then we step into the area of conjecture. Just the number of micro-watts please. At what low power input level does speech or music just BEGIN to fade out to a person of normal hearing? Any ideas? I could take the average of a few replies. Hi Reg, This will be have to be done through inference or Web research. As far as inference goes, I will first state that magnetic speaker efficiency is extremely poor, but I don't know if this extends to the headphone implementation. Albeit, between 1 and 10% efficient. The level of hearing for a child or teen fades out at 1db re environmental impositions. Technically, in the absence of other sounds: 1dB re 200µDynes per cM² at 1KHz 0dB = 200µDynes per cM² = 0.1 femtoWatt per cM² a quiet whisper = 6 femtoWatts per cM² conversation at 1M = 1 nanoWatt per cM² Hearing at another frequency such as 400Hz (common sidetone for CW) is 10dB weaker (hearing peaks about 5dB in the 2-4KHz region) and worsens as frequency lowers. Hearing loss in the 50-59 Age group for men at 1KHz is about 10dB Given "hearing" is subjective, a technical response is only as accurate as the knowledge of these variables (age, sex, frequency, efficiency). 73's Richard Clark, KB7QHC |
On Thu, 1 Jul 2004 19:43:02 +0000 (UTC), "Reg Edwards"
wrote: I am writing a program involving an antenna plus two coupled tuned circuits plus a matched simple receiver. I would like to know, crudely, the audio power input level to 2000-ohm, iron diaphragm headphones for a nice, comfortable, not too difficult listening level. Such as when the phones are used on a crystal and cat's whisker radio receiver. Odd, I was just corresponding over this very matter recently. Such headphones are more sensitive than modern 8-ohm varieties. I have a pair of 2000-ohm headphones but unfortunately no means of measuring power or voltage input. Then we step into the area of conjecture. Just the number of micro-watts please. At what low power input level does speech or music just BEGIN to fade out to a person of normal hearing? Any ideas? I could take the average of a few replies. Hi Reg, This will be have to be done through inference or Web research. As far as inference goes, I will first state that magnetic speaker efficiency is extremely poor, but I don't know if this extends to the headphone implementation. Albeit, between 1 and 10% efficient. The level of hearing for a child or teen fades out at 1db re environmental impositions. Technically, in the absence of other sounds: 1dB re 200µDynes per cM² at 1KHz 0dB = 200µDynes per cM² = 0.1 femtoWatt per cM² a quiet whisper = 6 femtoWatts per cM² conversation at 1M = 1 nanoWatt per cM² Hearing at another frequency such as 400Hz (common sidetone for CW) is 10dB weaker (hearing peaks about 5dB in the 2-4KHz region) and worsens as frequency lowers. Hearing loss in the 50-59 Age group for men at 1KHz is about 10dB Given "hearing" is subjective, a technical response is only as accurate as the knowledge of these variables (age, sex, frequency, efficiency). 73's Richard Clark, KB7QHC |
Rich, why don't you say you don't know. ;o)
--- Reg. |
Rich, why don't you say you don't know. ;o)
--- Reg. |
I would like to know, crudely, the audio power input level to 2000-ohm, iron
diaphragm headphones for a nice, comfortable, not too difficult listening level. Such as when the phones are used on a crystal and cat's whisker Hi Reg, Don't know either, but if you have access to a scope and a signal generator, you could find out what you want. I have these, but not some 2000 ohm phones. When I was a child playing around with crystal sets, I listened to a 1KW AM station about 1 KM away with a 25' wire, a germanium diode, and a 1000 ohm crystal earphone. The diode drop would be around 250 millivolts, and the listening level would be fine. Thats 250 mv into 1000 ohms. Ther are several crystal radio web sites that may provide more help. 73 Gary N4AST |
I would like to know, crudely, the audio power input level to 2000-ohm, iron
diaphragm headphones for a nice, comfortable, not too difficult listening level. Such as when the phones are used on a crystal and cat's whisker Hi Reg, Don't know either, but if you have access to a scope and a signal generator, you could find out what you want. I have these, but not some 2000 ohm phones. When I was a child playing around with crystal sets, I listened to a 1KW AM station about 1 KM away with a 25' wire, a germanium diode, and a 1000 ohm crystal earphone. The diode drop would be around 250 millivolts, and the listening level would be fine. Thats 250 mv into 1000 ohms. Ther are several crystal radio web sites that may provide more help. 73 Gary N4AST |
On Thu, 1 Jul 2004 22:18:27 +0000 (UTC), "Reg Edwards"
wrote: Rich, why don't you say you don't know. ;o) --- Reg. On Thu, 01 Jul 2004 20:43:37 GMT, Richard Clark wrote: I don't know Hi Reggie, What if I said 43? Do you actually read responses to your questions? Let's see, there's enough numbers in it to satisfy lord kelvinator, and enough principle in it to make sir plushbottom happy, and it even contains the structure of another unzipped program. Too demeaning to say thank you, hmmmm? 88's Richard Clark, KB7QHC |
On Thu, 1 Jul 2004 22:18:27 +0000 (UTC), "Reg Edwards"
wrote: Rich, why don't you say you don't know. ;o) --- Reg. On Thu, 01 Jul 2004 20:43:37 GMT, Richard Clark wrote: I don't know Hi Reggie, What if I said 43? Do you actually read responses to your questions? Let's see, there's enough numbers in it to satisfy lord kelvinator, and enough principle in it to make sir plushbottom happy, and it even contains the structure of another unzipped program. Too demeaning to say thank you, hmmmm? 88's Richard Clark, KB7QHC |
Reg Edwards wrote:
I am writing a program involving an antenna plus two coupled tuned circuits plus a matched simple receiver. I would like to know, crudely, the audio power input level to 2000-ohm, iron diaphragm headphones for a nice, comfortable, not too difficult listening level. Such as when the phones are used on a crystal and cat's whisker radio receiver. Such headphones are more sensitive than modern 8-ohm varieties. I have a pair of 2000-ohm headphones but unfortunately no means of measuring power or voltage input. Just the number of micro-watts please. At what low power input level does speech or music just BEGIN to fade out to a person of normal hearing? Any ideas? I could take the average of a few replies. ---- Reg, G4FGQ EH? WHAT DID HE SAY? :-) -------------------- Irv Finkleman, Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP Calgary, Alberta, Canada |
Reg Edwards wrote:
I am writing a program involving an antenna plus two coupled tuned circuits plus a matched simple receiver. I would like to know, crudely, the audio power input level to 2000-ohm, iron diaphragm headphones for a nice, comfortable, not too difficult listening level. Such as when the phones are used on a crystal and cat's whisker radio receiver. Such headphones are more sensitive than modern 8-ohm varieties. I have a pair of 2000-ohm headphones but unfortunately no means of measuring power or voltage input. Just the number of micro-watts please. At what low power input level does speech or music just BEGIN to fade out to a person of normal hearing? Any ideas? I could take the average of a few replies. ---- Reg, G4FGQ EH? WHAT DID HE SAY? :-) -------------------- Irv Finkleman, Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP Calgary, Alberta, Canada |
"Richard Clark" wrote in message ... On Thu, 1 Jul 2004 22:18:27 +0000 (UTC), "Reg Edwards" wrote: Rich, why don't you say you don't know. ;o) --- Reg. On Thu, 01 Jul 2004 20:43:37 GMT, Richard Clark wrote: I don't know Hi Reggie, What if I said 43? Do you actually read responses to your questions? Let's see, there's enough numbers in it to satisfy lord kelvinator, and enough principle in it to make sir plushbottom happy, and it even contains the structure of another unzipped program. Too demeaning to say thank you, hmmmm? 88's Richard Clark, KB7QHC ============================= Thank you for what? ;o) Anyway, what else do you expect from an Italian clown ? ---- Punchinello, G4FGQ |
"Richard Clark" wrote in message ... On Thu, 1 Jul 2004 22:18:27 +0000 (UTC), "Reg Edwards" wrote: Rich, why don't you say you don't know. ;o) --- Reg. On Thu, 01 Jul 2004 20:43:37 GMT, Richard Clark wrote: I don't know Hi Reggie, What if I said 43? Do you actually read responses to your questions? Let's see, there's enough numbers in it to satisfy lord kelvinator, and enough principle in it to make sir plushbottom happy, and it even contains the structure of another unzipped program. Too demeaning to say thank you, hmmmm? 88's Richard Clark, KB7QHC ============================= Thank you for what? ;o) Anyway, what else do you expect from an Italian clown ? ---- Punchinello, G4FGQ |
On Fri, 2 Jul 2004 14:48:34 +0000 (UTC), "Reg Edwards"
wrote: Thank you for what? ;o) Anyway, what else do you expect from an Italian clown ? Chuckles, however, unless I'm mistaken, you happen to be British, n'est pas? Or have you regenerated through too much of the vine? |
On Fri, 2 Jul 2004 14:48:34 +0000 (UTC), "Reg Edwards"
wrote: Thank you for what? ;o) Anyway, what else do you expect from an Italian clown ? Chuckles, however, unless I'm mistaken, you happen to be British, n'est pas? Or have you regenerated through too much of the vine? |
On Fri, 2 Jul 2004 15:21:22 +0000 (UTC), Harry Whitfield
wrote: Well, I didn't actually forget - I thought you would know the impedance of the type F phones. (-: They appear to be two 2000 ohm earpieces in series, so the impedance is presumably 4000 ohm. The DC resistance is 3860 ohm. I was on the limits of my generator's 50dB attenuation and on the limits of my voltmeter, so the threshold values are likely to be very approximate. We are in the region of 250 pW ! Which is spot on to a quiet whisper = 6 femtoWatts per cM² conversation at 1M = 1 nanoWatt per cM² Hi Harry, You will have to forgive our Brit, computation is a trial, nailing down specifics difficult, and hearing is not what it used to be. None of this is terribly difficult, so I am sure Reggie anticipated your answer, but simply out of Trollish behavior, he prefers to play naif (a bit beyond the pale at his age however). This is all, of course, to escape attribution for his intellectual sources for his upcoming software :-P You are welcome Punchinello, even if do you rustle this next release's code under your apron to hide your plagiarism from view. 73's Richard Clark, KB7QHC |
On Fri, 2 Jul 2004 15:21:22 +0000 (UTC), Harry Whitfield
wrote: Well, I didn't actually forget - I thought you would know the impedance of the type F phones. (-: They appear to be two 2000 ohm earpieces in series, so the impedance is presumably 4000 ohm. The DC resistance is 3860 ohm. I was on the limits of my generator's 50dB attenuation and on the limits of my voltmeter, so the threshold values are likely to be very approximate. We are in the region of 250 pW ! Which is spot on to a quiet whisper = 6 femtoWatts per cM² conversation at 1M = 1 nanoWatt per cM² Hi Harry, You will have to forgive our Brit, computation is a trial, nailing down specifics difficult, and hearing is not what it used to be. None of this is terribly difficult, so I am sure Reggie anticipated your answer, but simply out of Trollish behavior, he prefers to play naif (a bit beyond the pale at his age however). This is all, of course, to escape attribution for his intellectual sources for his upcoming software :-P You are welcome Punchinello, even if do you rustle this next release's code under your apron to hide your plagiarism from view. 73's Richard Clark, KB7QHC |
What if I said 43?
========================== If you had also mentioned the measurement units, such as femto-Watts, that would have been the ideal, even perfect, reply to my enquiry and would have deserved the congratulations of all and sundry. ---- Punchinello, G4FGQ |
What if I said 43?
========================== If you had also mentioned the measurement units, such as femto-Watts, that would have been the ideal, even perfect, reply to my enquiry and would have deserved the congratulations of all and sundry. ---- Punchinello, G4FGQ |
Reg, G4FGQ wrote:
"I would like to know, crudely, the audio input level to 2000-ohm, non diaphragm head phones for a nice, comfortable, not too difficult intensity level." First problem is sensitivity of the phones. These vary widely. Satisfactory reception also depends on competing noise in addition to signal strength. According to the FCC in the U.S.A., you may need 1/2 millivolt for satisfactory reception. A kilowatt radiated by a medium wave transmitter may produce about 200 millivolts/m at one mile. It depends on antenna and path. Field strength is proportional to the square root of the watts per square meter times 377. I used to live about 15 mile4s from a 50 KW station. The signal strength at a mile from the station could have been 1.5 volts/ m, and at 15 miles could have been 0.1 V/m. Point is, my crystal set drove a dynamic loudspeaker directly through the output transformer mounted on the speaker. It was clearly audible. Impedance presented to the crystal set was closer to 10,000 ohms at 1 KHz than to 2000 ohms. The speaker and its cabinet were from a battery vacuum-tube set. The audio power may have been less than a microwatt, but as a kid my ears were acute. My 2nd edition GE "Transistor Manual" has 2000-ohm headphone amplifiers with 2 milliwatts maximum power output. Chinese stereo headphones claim 20-20KHz response, 32-ohms impedance, 100dB/1mW sensitivity, 140 mW rated input, 400 mW max. etc. Much of this spec. is target and untrue. Wide variations exist between samples of these phones claiming similar specs. The GE book is believable. Class A power output is from the familiar. First formula says maximum power is 1/2 the product of the peak voltage and peak current. Load resistance is then the peak voltage divided by the peak current. So, Load resistance=Epk squared/2Po When GE prints the circuit of a 2 milliwatt amplifier driving 2000-ohm phones, I believe it works. Best regards, Richard Harrison, KB5WZI |
Reg, G4FGQ wrote:
"I would like to know, crudely, the audio input level to 2000-ohm, non diaphragm head phones for a nice, comfortable, not too difficult intensity level." First problem is sensitivity of the phones. These vary widely. Satisfactory reception also depends on competing noise in addition to signal strength. According to the FCC in the U.S.A., you may need 1/2 millivolt for satisfactory reception. A kilowatt radiated by a medium wave transmitter may produce about 200 millivolts/m at one mile. It depends on antenna and path. Field strength is proportional to the square root of the watts per square meter times 377. I used to live about 15 mile4s from a 50 KW station. The signal strength at a mile from the station could have been 1.5 volts/ m, and at 15 miles could have been 0.1 V/m. Point is, my crystal set drove a dynamic loudspeaker directly through the output transformer mounted on the speaker. It was clearly audible. Impedance presented to the crystal set was closer to 10,000 ohms at 1 KHz than to 2000 ohms. The speaker and its cabinet were from a battery vacuum-tube set. The audio power may have been less than a microwatt, but as a kid my ears were acute. My 2nd edition GE "Transistor Manual" has 2000-ohm headphone amplifiers with 2 milliwatts maximum power output. Chinese stereo headphones claim 20-20KHz response, 32-ohms impedance, 100dB/1mW sensitivity, 140 mW rated input, 400 mW max. etc. Much of this spec. is target and untrue. Wide variations exist between samples of these phones claiming similar specs. The GE book is believable. Class A power output is from the familiar. First formula says maximum power is 1/2 the product of the peak voltage and peak current. Load resistance is then the peak voltage divided by the peak current. So, Load resistance=Epk squared/2Po When GE prints the circuit of a 2 milliwatt amplifier driving 2000-ohm phones, I believe it works. Best regards, Richard Harrison, KB5WZI |
On Fri, 2 Jul 2004 16:45:12 +0000 (UTC), "Reg Edwards"
wrote: What if I said 43? ========================== If you had also mentioned the measurement units, such as femto-Watts, that would have been the ideal, even perfect, reply to my enquiry and would have deserved the congratulations of all and sundry. ---- Punchinello, G4FGQ Ah Shirley! You jest. Thanks uttered by Punchinello? Time and tide wait for no such unlikely occasion. Lord Kelvinator wouldn't be very proud of you, old son, if I had to lead you by the hand through ALL of the work, much less spoon fed you the answer. It is only a matter of simple junior high math employing conversions (all the numbers are already there). About as demanding as chinese checker strategy. 88's Richard Clark, KB7QHC |
On Fri, 2 Jul 2004 16:45:12 +0000 (UTC), "Reg Edwards"
wrote: What if I said 43? ========================== If you had also mentioned the measurement units, such as femto-Watts, that would have been the ideal, even perfect, reply to my enquiry and would have deserved the congratulations of all and sundry. ---- Punchinello, G4FGQ Ah Shirley! You jest. Thanks uttered by Punchinello? Time and tide wait for no such unlikely occasion. Lord Kelvinator wouldn't be very proud of you, old son, if I had to lead you by the hand through ALL of the work, much less spoon fed you the answer. It is only a matter of simple junior high math employing conversions (all the numbers are already there). About as demanding as chinese checker strategy. 88's Richard Clark, KB7QHC |
Dear Rich, in your own best interests you should merely have said "I don't
know.". Or better still - - - silence. ---- Punch, G4FGQ |
Dear Rich, in your own best interests you should merely have said "I don't
know.". Or better still - - - silence. ---- Punch, G4FGQ |
On Fri, 2 Jul 2004 22:09:13 +0000 (UTC), "Reg Edwards"
wrote: Dear Rich, in your own best interests you should merely have said "I don't know.". Oh the ravage of age upon you - here it is again On Thu, 01 Jul 2004 20:43:37 GMT, Richard Clark wrote: I don't know Or better still - - - silence. ---- Punch, G4FGQ My own best interests? Somehow I don't see you in the confessional offering Ave Marias to me (now there is an image, Punchinello with a Mitre - the pope and you both like funny hats). I'm still not going to spoon feed you, you know. Do you have a number yet? Or is this the better, silence? ;-0 73's Richard Clark, KB7QHC |
On Fri, 2 Jul 2004 22:09:13 +0000 (UTC), "Reg Edwards"
wrote: Dear Rich, in your own best interests you should merely have said "I don't know.". Oh the ravage of age upon you - here it is again On Thu, 01 Jul 2004 20:43:37 GMT, Richard Clark wrote: I don't know Or better still - - - silence. ---- Punch, G4FGQ My own best interests? Somehow I don't see you in the confessional offering Ave Marias to me (now there is an image, Punchinello with a Mitre - the pope and you both like funny hats). I'm still not going to spoon feed you, you know. Do you have a number yet? Or is this the better, silence? ;-0 73's Richard Clark, KB7QHC |
Harry Whitfield wrote:
"Sensitivity is given as 112 dB at 1 mW. I assume this means 112 dB above the Threshold of Hearing (1pW per square metre) at 1 mW in." That looks OK to me. My handy "Science Answer Book says: Hearing starts at zero decibels. 10 units is a tenfold increase. The sound made by leaves rustling is often 10 decibels. Office noise level is typically 50 decibels. A pneumatic drill = 80 dB. A riveting machine = 110 dB. A jet takeoff at 61 m (200 ft.) measures 120 dB. Noise above 70 decibels harms hearing. At 140 dB, noise is physically painful. Acute hearing is sensitive. More so in some other species. In a previous posting I may have appeared naive saying I believed GE produced a circuit for a 2 milliwatt 2000-ohm headphone amplifier. But I have additional evidence of the adequacy of 2 milliwatts. For many years I worked at a radio station where we kept a pair of crystal phones near the audio patch panel. These, because of their extremely high impedance, could be bridged across any program line with no significant effect. Program lines are usually adjusted to a zero VU level (1 milliwatt into 600 ohms) or 0.775 volt on program peaks. Magnetic phones produced about the same audio output with 0.775 volts as did the crystal cans. The difference is only in the circuit loading of the 2000-ohm magnetic phones on a 600-ohm circuit. Point is, one milliwatt is plenty loud in headphones. I know from listening. Best regards, Richard Harrison, KB5WZI |
Harry Whitfield wrote:
"Sensitivity is given as 112 dB at 1 mW. I assume this means 112 dB above the Threshold of Hearing (1pW per square metre) at 1 mW in." That looks OK to me. My handy "Science Answer Book says: Hearing starts at zero decibels. 10 units is a tenfold increase. The sound made by leaves rustling is often 10 decibels. Office noise level is typically 50 decibels. A pneumatic drill = 80 dB. A riveting machine = 110 dB. A jet takeoff at 61 m (200 ft.) measures 120 dB. Noise above 70 decibels harms hearing. At 140 dB, noise is physically painful. Acute hearing is sensitive. More so in some other species. In a previous posting I may have appeared naive saying I believed GE produced a circuit for a 2 milliwatt 2000-ohm headphone amplifier. But I have additional evidence of the adequacy of 2 milliwatts. For many years I worked at a radio station where we kept a pair of crystal phones near the audio patch panel. These, because of their extremely high impedance, could be bridged across any program line with no significant effect. Program lines are usually adjusted to a zero VU level (1 milliwatt into 600 ohms) or 0.775 volt on program peaks. Magnetic phones produced about the same audio output with 0.775 volts as did the crystal cans. The difference is only in the circuit loading of the 2000-ohm magnetic phones on a 600-ohm circuit. Point is, one milliwatt is plenty loud in headphones. I know from listening. Best regards, Richard Harrison, KB5WZI |
John, MW1FGQ wrote:
"I used to carry a pair of old military headphonees in my kit when building broadcast installations until they were nicked by some ****." Several models of telephone receivers were used in WW-2, including the TS-10 (sound powered) unit. This was probably the most efficient transducer except for the R-13 and other resonant models designed for morse code reception. The HS-33 with its leather-covered headband is the model I saw most often. I don`t remember it being particularly sensitive but it did have pretty good fidelity. I seem to recall seeing the most valuable patent ever issued by the U. S. Patent Office. It`s the Alexander G. Bell telephone patent. The microphone was dynamic, not carbon, so his receiver had to be sensitive as the instrument was sound powered. I used to carry around a surplus TS-10 unit in my kit. Although sound powered, it is not sharply resonant. The fidelity is not too bad. Aboard my ship in WW-2, I had a spare TS-10 unit wired with an attenuator and connected to the ship`s entertainment and information line. There was an almost 24-hour music feed from radio or records. We had a V-disk transcription library too. Nobody complained and the zero dBm level was plenty loud if I turned up the attenuator. Little electrical power is needed for considerable acoustical power when using the right transducer. As long as I kept the movie projector running, the skipper would let me get away with about anything. Best Regards, Richard Harrison, KB5WZI |
John, MW1FGQ wrote:
"I used to carry a pair of old military headphonees in my kit when building broadcast installations until they were nicked by some ****." Several models of telephone receivers were used in WW-2, including the TS-10 (sound powered) unit. This was probably the most efficient transducer except for the R-13 and other resonant models designed for morse code reception. The HS-33 with its leather-covered headband is the model I saw most often. I don`t remember it being particularly sensitive but it did have pretty good fidelity. I seem to recall seeing the most valuable patent ever issued by the U. S. Patent Office. It`s the Alexander G. Bell telephone patent. The microphone was dynamic, not carbon, so his receiver had to be sensitive as the instrument was sound powered. I used to carry around a surplus TS-10 unit in my kit. Although sound powered, it is not sharply resonant. The fidelity is not too bad. Aboard my ship in WW-2, I had a spare TS-10 unit wired with an attenuator and connected to the ship`s entertainment and information line. There was an almost 24-hour music feed from radio or records. We had a V-disk transcription library too. Nobody complained and the zero dBm level was plenty loud if I turned up the attenuator. Little electrical power is needed for considerable acoustical power when using the right transducer. As long as I kept the movie projector running, the skipper would let me get away with about anything. Best Regards, Richard Harrison, KB5WZI |
On Thu, 1 Jul 2004 19:43:02 +0000 (UTC), "Reg Edwards"
wrote: I could take the average of a few replies. Hi All, Perhaps an exercise useful to approximate within 2 or 3 orders of magnitude. The problem with measuring against the physiological response (aka hearing, seeing, and the other senses) is that we "own" the estimate as a personal expression of our integrity (how could be wrong?). Problem is that such measurements are invariably fraught with the widest error spread imaginable. For a simple correlation (based on the cool, calm, detachment of instrumentation) I noted the specifications for my speakers (Pioneer vintage mid 70s) which describe they are capable of producing a SPL (sound pressure level) of 92dB @ 1M @ 1 Watt. They also supply a chart of relative sensitivity across the band of 20-20000 Hz, Harmonic distortion, Impedances (room and coil). The published variation shows that premium equipment wanders to considerable degree (Z, nominally at 10 Ohms varies from 5 Ohms to a peaked 40 Ohms). Hence nearly every audio specification is set at either 1KHz or 400Hz and those practitioners know full well not to abstract them throughout their hearing range (which they also know full well varies with even much wilder swings). Let's take that same 92dB @ 1M @ 1 Watt and compare to the several reports of hi-Z headsets. The first translation is of course against application. Headphones encompass far less distance than 1M. I will arbitrarily assign a path link of 1cM for the ear canal and re-specify my Pioneer speakers to 112dB @ 1W (basically with the ear pressed next to the speaker cone). If I simply derate the power to achieve to 2dB above the threshold of hearing (110 of that same 112dB) the power is similarly derated to 1W / 10¹¹ or 10 picoWatts On Thu, 01 Jul 2004 21:06:10 GMT, "H. Adam Stevens" wrote: I can report using Sennheiser hi impedance dynamic phones to monitor 600 ohm balanced broadcast audio signals ... The signal qualified as a good listening level as I recall. "good" is too inspecific to derate to threshold power level. On 01 Jul 2004 22:57:11 GMT, (JGBOYLES) wrote: a 1000 ohm crystal earphone. The diode drop would be around 250 millivolts, and the listening level would be fine. "fine" is too inspecific to derate to threshold power level. On Thu, 01 Jul 2004 23:44:01 GMT, "owen.home" wrote: I dont think they were as high as 2k but they were not low Z so probably 600ohms and very sensitive ... could just hear -60dBm "just hear" suggests threshold at 1 nanoWatt or 1000 picoWatts or 2 orders of magnitude worse than my speakers. On Thu, 1 Jul 2004 20:55:15 -0500, "Nick Kennedy" wrote: iron diaphragm, engraved on the back "Cannonball Dixie, E.F. Cannon Co., Springwater, N.Y., U.S.A" I measured the resistance of each can at a little over 1000 ohms. The sound was clearly audible but not strong. ... 0.084 uW. "clearly audible" is inspecific, however 84 nanoWatts or 84000 picoWatts or nearly 4 orders of magnitude worse than my speakers. On Fri, 2 Jul 2004 13:39:59 +0000 (UTC), Harry Whitfield wrote: Test with S G Brown Type F Headphones 0.001 [Vrms] Threshold [@ 1KHz] [and in a follow-up] The DC resistance is 3860 ohm. We are in the region of 250 pW ! [and a third follow-up] I (also) have a very old pair of Philips Hi-Fi headphones. The spec is given as 2 x 600 ohm (they are stereo phones). Sensitivity is given as 112dB at 1mW. -whew!- 2dB level at 10 femtoWatts Harry offers the wildest variation. His first SG Browns are 25 times worse than my speakers however his Philips Hi-Fi headphones 3 orders of magnitude better than my speakers! Hence, as an average, response to this question spans roughly 7 orders of magnitude. As the quality of unzipped (and unrevealed design) software goes, such a spread could easily satisfy anyone, even boys in their treehouse with a string and dixie cup telephone system. What accounts for this ENORMOUS swing of response to a simple enquiry? The human element of owning what amounts to "dead reckoning." The perception of sound is individual, not absolute. Through the survey above it also suffers in reporting too few variables. In other words, just what dB level satisfies such qualities as "just hear" "clearly audible" "good" "fine" and any other subjective qualifiers? The nearly 7 decades of variation cover roughly half the hearing range between threshold and pain - 140dB. Obviously if we trimmed 40dB from each end, the middle zone of the remaining 60dB suddenly becomes "average" listening levels for "someone." Well, I hope you guys enjoyed this tour of the fantastic improbability of human sensation rendered to a fixed number. ;-) 73's Richard Clark, KB7QHC |
On Thu, 1 Jul 2004 19:43:02 +0000 (UTC), "Reg Edwards"
wrote: I could take the average of a few replies. Hi All, Perhaps an exercise useful to approximate within 2 or 3 orders of magnitude. The problem with measuring against the physiological response (aka hearing, seeing, and the other senses) is that we "own" the estimate as a personal expression of our integrity (how could be wrong?). Problem is that such measurements are invariably fraught with the widest error spread imaginable. For a simple correlation (based on the cool, calm, detachment of instrumentation) I noted the specifications for my speakers (Pioneer vintage mid 70s) which describe they are capable of producing a SPL (sound pressure level) of 92dB @ 1M @ 1 Watt. They also supply a chart of relative sensitivity across the band of 20-20000 Hz, Harmonic distortion, Impedances (room and coil). The published variation shows that premium equipment wanders to considerable degree (Z, nominally at 10 Ohms varies from 5 Ohms to a peaked 40 Ohms). Hence nearly every audio specification is set at either 1KHz or 400Hz and those practitioners know full well not to abstract them throughout their hearing range (which they also know full well varies with even much wilder swings). Let's take that same 92dB @ 1M @ 1 Watt and compare to the several reports of hi-Z headsets. The first translation is of course against application. Headphones encompass far less distance than 1M. I will arbitrarily assign a path link of 1cM for the ear canal and re-specify my Pioneer speakers to 112dB @ 1W (basically with the ear pressed next to the speaker cone). If I simply derate the power to achieve to 2dB above the threshold of hearing (110 of that same 112dB) the power is similarly derated to 1W / 10¹¹ or 10 picoWatts On Thu, 01 Jul 2004 21:06:10 GMT, "H. Adam Stevens" wrote: I can report using Sennheiser hi impedance dynamic phones to monitor 600 ohm balanced broadcast audio signals ... The signal qualified as a good listening level as I recall. "good" is too inspecific to derate to threshold power level. On 01 Jul 2004 22:57:11 GMT, (JGBOYLES) wrote: a 1000 ohm crystal earphone. The diode drop would be around 250 millivolts, and the listening level would be fine. "fine" is too inspecific to derate to threshold power level. On Thu, 01 Jul 2004 23:44:01 GMT, "owen.home" wrote: I dont think they were as high as 2k but they were not low Z so probably 600ohms and very sensitive ... could just hear -60dBm "just hear" suggests threshold at 1 nanoWatt or 1000 picoWatts or 2 orders of magnitude worse than my speakers. On Thu, 1 Jul 2004 20:55:15 -0500, "Nick Kennedy" wrote: iron diaphragm, engraved on the back "Cannonball Dixie, E.F. Cannon Co., Springwater, N.Y., U.S.A" I measured the resistance of each can at a little over 1000 ohms. The sound was clearly audible but not strong. ... 0.084 uW. "clearly audible" is inspecific, however 84 nanoWatts or 84000 picoWatts or nearly 4 orders of magnitude worse than my speakers. On Fri, 2 Jul 2004 13:39:59 +0000 (UTC), Harry Whitfield wrote: Test with S G Brown Type F Headphones 0.001 [Vrms] Threshold [@ 1KHz] [and in a follow-up] The DC resistance is 3860 ohm. We are in the region of 250 pW ! [and a third follow-up] I (also) have a very old pair of Philips Hi-Fi headphones. The spec is given as 2 x 600 ohm (they are stereo phones). Sensitivity is given as 112dB at 1mW. -whew!- 2dB level at 10 femtoWatts Harry offers the wildest variation. His first SG Browns are 25 times worse than my speakers however his Philips Hi-Fi headphones 3 orders of magnitude better than my speakers! Hence, as an average, response to this question spans roughly 7 orders of magnitude. As the quality of unzipped (and unrevealed design) software goes, such a spread could easily satisfy anyone, even boys in their treehouse with a string and dixie cup telephone system. What accounts for this ENORMOUS swing of response to a simple enquiry? The human element of owning what amounts to "dead reckoning." The perception of sound is individual, not absolute. Through the survey above it also suffers in reporting too few variables. In other words, just what dB level satisfies such qualities as "just hear" "clearly audible" "good" "fine" and any other subjective qualifiers? The nearly 7 decades of variation cover roughly half the hearing range between threshold and pain - 140dB. Obviously if we trimmed 40dB from each end, the middle zone of the remaining 60dB suddenly becomes "average" listening levels for "someone." Well, I hope you guys enjoyed this tour of the fantastic improbability of human sensation rendered to a fixed number. ;-) 73's Richard Clark, KB7QHC |
On Thu, 1 Jul 2004 19:43:02 +0000 (UTC), "Reg Edwards"
wrote: I could take the average of a few replies. Hi All, Perhaps an exercise useful to approximate within 2 or 3 orders of magnitude. The problem with measuring against the physiological response (aka hearing, seeing, and the other senses) is that we "own" the estimate as a personal expression of our integrity (how could be wrong?). Problem is that such measurements are invariably fraught with the widest error spread imaginable. For a simple correlation (based on the cool, calm, detachment of instrumentation) I noted the specifications for my speakers (Pioneer vintage mid 70s) which describe they are capable of producing a SPL (sound pressure level) of 92dB @ 1M @ 1 Watt. They also supply a chart of relative sensitivity across the band of 20-20000 Hz, Harmonic distortion, Impedances (room and coil). The published variation shows that premium equipment wanders to considerable degree (Z, nominally at 10 Ohms varies from 5 Ohms to a peaked 40 Ohms). Hence nearly every audio specification is set at either 1KHz or 400Hz and those practitioners know full well not to abstract them throughout their hearing range (which they also know full well varies with even much wilder swings). Let's take that same 92dB @ 1M @ 1 Watt and compare to the several reports of hi-Z headsets. The first translation is of course against application. Headphones encompass far less distance than 1M. I will arbitrarily assign a path link of 1cM for the ear canal and re-specify my Pioneer speakers to 112dB @ 1W (basically with the ear pressed next to the speaker cone). If I simply derate the power to achieve to 2dB above the threshold of hearing (110 of that same 112dB) the power is similarly derated to 1W / 10¹¹ or 10 picoWatts On Thu, 01 Jul 2004 21:06:10 GMT, "H. Adam Stevens" wrote: I can report using Sennheiser hi impedance dynamic phones to monitor 600 ohm balanced broadcast audio signals ... The signal qualified as a good listening level as I recall. "good" is too inspecific to derate to threshold power level. On 01 Jul 2004 22:57:11 GMT, (JGBOYLES) wrote: a 1000 ohm crystal earphone. The diode drop would be around 250 millivolts, and the listening level would be fine. "fine" is too inspecific to derate to threshold power level. On Thu, 01 Jul 2004 23:44:01 GMT, "owen.home" wrote: I dont think they were as high as 2k but they were not low Z so probably 600ohms and very sensitive ... could just hear -60dBm "just hear" suggests threshold at 1 nanoWatt or 1000 picoWatts or 2 orders of magnitude worse than my speakers. On Thu, 1 Jul 2004 20:55:15 -0500, "Nick Kennedy" wrote: iron diaphragm, engraved on the back "Cannonball Dixie, E.F. Cannon Co., Springwater, N.Y., U.S.A" I measured the resistance of each can at a little over 1000 ohms. The sound was clearly audible but not strong. ... 0.084 uW. "clearly audible" is inspecific, however 84 nanoWatts or 84000 picoWatts or nearly 4 orders of magnitude worse than my speakers. On Fri, 2 Jul 2004 13:39:59 +0000 (UTC), Harry Whitfield wrote: Test with S G Brown Type F Headphones 0.001 [Vrms] Threshold [@ 1KHz] [and in a follow-up] The DC resistance is 3860 ohm. We are in the region of 250 pW ! [and a third follow-up] I (also) have a very old pair of Philips Hi-Fi headphones. The spec is given as 2 x 600 ohm (they are stereo phones). Sensitivity is given as 112dB at 1mW. -whew!- 2dB level at 10 femtoWatts Harry offers the wildest variation. His first SG Browns are 25 times worse than my speakers however his Philips Hi-Fi headphones 3 orders of magnitude better than my speakers! Hence, as an average, response to this question spans roughly 7 orders of magnitude. As the quality of unzipped (and unrevealed design) software goes, such a spread could easily satisfy anyone, even boys in their treehouse with a string and dixie cup telephone system. What accounts for this ENORMOUS swing of response to a simple enquiry? The human element of owning what amounts to "dead reckoning." The perception of sound is individual, not absolute. Through the survey above it also suffers in reporting too few variables. In other words, just what dB level satisfies such qualities as "just hear" "clearly audible" "good" "fine" and any other subjective qualifiers? The nearly 7 decades of variation cover roughly half the hearing range between threshold and pain - 140dB. Obviously if we trimmed 40dB from each end, the middle zone of the remaining 60dB suddenly becomes "average" listening levels for "someone." Well, I hope you guys enjoyed this tour of the fantastic improbability of human sensation rendered to a fixed number. ;-) 73's Richard Clark, KB7QHC |
On Thu, 1 Jul 2004 19:43:02 +0000 (UTC), "Reg Edwards"
wrote: I could take the average of a few replies. Hi All, Perhaps an exercise useful to approximate within 2 or 3 orders of magnitude. The problem with measuring against the physiological response (aka hearing, seeing, and the other senses) is that we "own" the estimate as a personal expression of our integrity (how could be wrong?). Problem is that such measurements are invariably fraught with the widest error spread imaginable. For a simple correlation (based on the cool, calm, detachment of instrumentation) I noted the specifications for my speakers (Pioneer vintage mid 70s) which describe they are capable of producing a SPL (sound pressure level) of 92dB @ 1M @ 1 Watt. They also supply a chart of relative sensitivity across the band of 20-20000 Hz, Harmonic distortion, Impedances (room and coil). The published variation shows that premium equipment wanders to considerable degree (Z, nominally at 10 Ohms varies from 5 Ohms to a peaked 40 Ohms). Hence nearly every audio specification is set at either 1KHz or 400Hz and those practitioners know full well not to abstract them throughout their hearing range (which they also know full well varies with even much wilder swings). Let's take that same 92dB @ 1M @ 1 Watt and compare to the several reports of hi-Z headsets. The first translation is of course against application. Headphones encompass far less distance than 1M. I will arbitrarily assign a path link of 1cM for the ear canal and re-specify my Pioneer speakers to 112dB @ 1W (basically with the ear pressed next to the speaker cone). If I simply derate the power to achieve to 2dB above the threshold of hearing (110 of that same 112dB) the power is similarly derated to 1W / 10¹¹ or 10 picoWatts On Thu, 01 Jul 2004 21:06:10 GMT, "H. Adam Stevens" wrote: I can report using Sennheiser hi impedance dynamic phones to monitor 600 ohm balanced broadcast audio signals ... The signal qualified as a good listening level as I recall. "good" is too inspecific to derate to threshold power level. On 01 Jul 2004 22:57:11 GMT, (JGBOYLES) wrote: a 1000 ohm crystal earphone. The diode drop would be around 250 millivolts, and the listening level would be fine. "fine" is too inspecific to derate to threshold power level. On Thu, 01 Jul 2004 23:44:01 GMT, "owen.home" wrote: I dont think they were as high as 2k but they were not low Z so probably 600ohms and very sensitive ... could just hear -60dBm "just hear" suggests threshold at 1 nanoWatt or 1000 picoWatts or 2 orders of magnitude worse than my speakers. On Thu, 1 Jul 2004 20:55:15 -0500, "Nick Kennedy" wrote: iron diaphragm, engraved on the back "Cannonball Dixie, E.F. Cannon Co., Springwater, N.Y., U.S.A" I measured the resistance of each can at a little over 1000 ohms. The sound was clearly audible but not strong. ... 0.084 uW. "clearly audible" is inspecific, however 84 nanoWatts or 84000 picoWatts or nearly 4 orders of magnitude worse than my speakers. On Fri, 2 Jul 2004 13:39:59 +0000 (UTC), Harry Whitfield wrote: Test with S G Brown Type F Headphones 0.001 [Vrms] Threshold [@ 1KHz] [and in a follow-up] The DC resistance is 3860 ohm. We are in the region of 250 pW ! [and a third follow-up] I (also) have a very old pair of Philips Hi-Fi headphones. The spec is given as 2 x 600 ohm (they are stereo phones). Sensitivity is given as 112dB at 1mW. -whew!- 2dB level at 10 femtoWatts Harry offers the wildest variation. His first SG Browns are 25 times worse than my speakers however his Philips Hi-Fi headphones 3 orders of magnitude better than my speakers! Hence, as an average, response to this question spans roughly 7 orders of magnitude. As the quality of unzipped (and unrevealed design) software goes, such a spread could easily satisfy anyone, even boys in their treehouse with a string and dixie cup telephone system. What accounts for this ENORMOUS swing of response to a simple enquiry? The human element of owning what amounts to "dead reckoning." The perception of sound is individual, not absolute. Through the survey above it also suffers in reporting too few variables. In other words, just what dB level satisfies such qualities as "just hear" "clearly audible" "good" "fine" and any other subjective qualifiers? The nearly 7 decades of variation cover roughly half the hearing range between threshold and pain - 140dB. Obviously if we trimmed 40dB from each end, the middle zone of the remaining 60dB suddenly becomes "average" listening levels for "someone." Well, I hope you guys enjoyed this tour of the fantastic improbability of human sensation rendered to a fixed number. ;-) 73's Richard Clark, KB7QHC |
On Thu, 1 Jul 2004 19:43:02 +0000 (UTC), "Reg Edwards"
wrote: I could take the average of a few replies. Hi All, Perhaps an exercise useful to approximate within 2 or 3 orders of magnitude. The problem with measuring against the physiological response (aka hearing, seeing, and the other senses) is that we "own" the estimate as a personal expression of our integrity (how could be wrong?). Problem is that such measurements are invariably fraught with the widest error spread imaginable. For a simple correlation (based on the cool, calm, detachment of instrumentation) I noted the specifications for my speakers (Pioneer vintage mid 70s) which describe they are capable of producing a SPL (sound pressure level) of 92dB @ 1M @ 1 Watt. They also supply a chart of relative sensitivity across the band of 20-20000 Hz, Harmonic distortion, Impedances (room and coil). The published variation shows that premium equipment wanders to considerable degree (Z, nominally at 10 Ohms varies from 5 Ohms to a peaked 40 Ohms). Hence nearly every audio specification is set at either 1KHz or 400Hz and those practitioners know full well not to abstract them throughout their hearing range (which they also know full well varies with even much wilder swings). Let's take that same 92dB @ 1M @ 1 Watt and compare to the several reports of hi-Z headsets. The first translation is of course against application. Headphones encompass far less distance than 1M. I will arbitrarily assign a path link of 1cM for the ear canal and re-specify my Pioneer speakers to 112dB @ 1W (basically with the ear pressed next to the speaker cone). If I simply derate the power to achieve to 2dB above the threshold of hearing (110 of that same 112dB) the power is similarly derated to 1W / 10¹¹ or 10 picoWatts On Thu, 01 Jul 2004 21:06:10 GMT, "H. Adam Stevens" wrote: I can report using Sennheiser hi impedance dynamic phones to monitor 600 ohm balanced broadcast audio signals ... The signal qualified as a good listening level as I recall. "good" is too inspecific to derate to threshold power level. On 01 Jul 2004 22:57:11 GMT, (JGBOYLES) wrote: a 1000 ohm crystal earphone. The diode drop would be around 250 millivolts, and the listening level would be fine. "fine" is too inspecific to derate to threshold power level. On Thu, 01 Jul 2004 23:44:01 GMT, "owen.home" wrote: I dont think they were as high as 2k but they were not low Z so probably 600ohms and very sensitive ... could just hear -60dBm "just hear" suggests threshold at 1 nanoWatt or 1000 picoWatts or 2 orders of magnitude worse than my speakers. On Thu, 1 Jul 2004 20:55:15 -0500, "Nick Kennedy" wrote: iron diaphragm, engraved on the back "Cannonball Dixie, E.F. Cannon Co., Springwater, N.Y., U.S.A" I measured the resistance of each can at a little over 1000 ohms. The sound was clearly audible but not strong. ... 0.084 uW. "clearly audible" is inspecific, however 84 nanoWatts or 84000 picoWatts or nearly 4 orders of magnitude worse than my speakers. On Fri, 2 Jul 2004 13:39:59 +0000 (UTC), Harry Whitfield wrote: Test with S G Brown Type F Headphones 0.001 [Vrms] Threshold [@ 1KHz] [and in a follow-up] The DC resistance is 3860 ohm. We are in the region of 250 pW ! [and a third follow-up] I (also) have a very old pair of Philips Hi-Fi headphones. The spec is given as 2 x 600 ohm (they are stereo phones). Sensitivity is given as 112dB at 1mW. -whew!- 2dB level at 10 femtoWatts Harry offers the wildest variation. His first SG Browns are 25 times worse than my speakers however his Philips Hi-Fi headphones 3 orders of magnitude better than my speakers! Hence, as an average, response to this question spans roughly 7 orders of magnitude. As the quality of unzipped (and unrevealed design) software goes, such a spread could easily satisfy anyone, even boys in their treehouse with a string and dixie cup telephone system. What accounts for this ENORMOUS swing of response to a simple enquiry? The human element of owning what amounts to "dead reckoning." The perception of sound is individual, not absolute. Through the survey above it also suffers in reporting too few variables. In other words, just what dB level satisfies such qualities as "just hear" "clearly audible" "good" "fine" and any other subjective qualifiers? The nearly 7 decades of variation cover roughly half the hearing range between threshold and pain - 140dB. Obviously if we trimmed 40dB from each end, the middle zone of the remaining 60dB suddenly becomes "average" listening levels for "someone." Well, I hope you guys enjoyed this tour of the fantastic improbability of human sensation rendered to a fixed number. ;-) 73's Richard Clark, KB7QHC |
Richard Clark wrote:
"It just occiurred to me that my mock response of 43 is as good as any-....." Almost, but the subject does have reference points though "threshold of hearing" has almost as many values as there are people, or maybe more than the population, depending on conditions. Keith Henney in his 1938 "Principles of Radio" says: "Loudspeakers in general are notoriously inefficient - the best in common use is not over 30 per cent. Most of them are less than 5% efficient." In the years since 1938, efficiency has not made a big improvement. Headphones are likewise inefficient and vary widely from sample to sample. Harold Ennes says in "Broadcast Maintenance": "A level of 0.0002 dyne per square centimeter is considered to be the threshold of audibility." According to Fig 1-4 in the Ennes book, this is an intensity of 0 db. A sound pressure of 0.00002 dynes per square centimeter is a sound intensity of -20 dB, while 0.002 dynes per square centimeter is +20 dB. Broadcast microphones are said to produce a power output of from -50 to -65 dBm at a sound pressure of 10 dynes per square centimeter. Sound transducers are said to vary by 15 dB in sensitivity among those of the best quality, and that is at a particular reference frequency and without variations which depend on the location of the source with respect to the microphone above. Then think of a comparison of individual response curves of sound transducers. It`s somewhat chaotic. A description of headphone performance can be made which can be useful to compare performance despite all of the problems. Microphones and headsets of WW-2 are charted in "Electrical Communication Systems Engineering" published by the War Department in April 1945. Useful characterizations can also be made of other sound transducers. Best regards, Richard Harrison, KB5WZI |
Richard Clark wrote:
"It just occiurred to me that my mock response of 43 is as good as any-....." Almost, but the subject does have reference points though "threshold of hearing" has almost as many values as there are people, or maybe more than the population, depending on conditions. Keith Henney in his 1938 "Principles of Radio" says: "Loudspeakers in general are notoriously inefficient - the best in common use is not over 30 per cent. Most of them are less than 5% efficient." In the years since 1938, efficiency has not made a big improvement. Headphones are likewise inefficient and vary widely from sample to sample. Harold Ennes says in "Broadcast Maintenance": "A level of 0.0002 dyne per square centimeter is considered to be the threshold of audibility." According to Fig 1-4 in the Ennes book, this is an intensity of 0 db. A sound pressure of 0.00002 dynes per square centimeter is a sound intensity of -20 dB, while 0.002 dynes per square centimeter is +20 dB. Broadcast microphones are said to produce a power output of from -50 to -65 dBm at a sound pressure of 10 dynes per square centimeter. Sound transducers are said to vary by 15 dB in sensitivity among those of the best quality, and that is at a particular reference frequency and without variations which depend on the location of the source with respect to the microphone above. Then think of a comparison of individual response curves of sound transducers. It`s somewhat chaotic. A description of headphone performance can be made which can be useful to compare performance despite all of the problems. Microphones and headsets of WW-2 are charted in "Electrical Communication Systems Engineering" published by the War Department in April 1945. Useful characterizations can also be made of other sound transducers. Best regards, Richard Harrison, KB5WZI |
On Sat, 03 Jul 2004 18:41:00 GMT, Richard Clark
wrote: Let's take that same 92dB @ 1M @ 1 Watt and compare to the several reports of hi-Z headsets. The first translation is of course against application. Headphones encompass far less distance than 1M. I will arbitrarily assign a path link of 1cM for the ear canal and re-specify my Pioneer speakers to 112dB @ 1W (basically with the ear pressed next to the speaker cone). Should be 132dB @ 1W - which, of course, does nothing to the spread of reported responses. However, even this correction is fraught with error because it presumes a free field (violated at the ear canal where it becomes a pressure field) - well, such are the pitfalls of computing with sound. For those seriously interested in the Physics of sound, vibration, and its measurement, the preeminent authority in this field is in Denmark with Brüel and Kjær: http://www.bksv.com/pdf/Sound_Intensity.pdf who offer microphones that can pick up sound 40dB below the threshold of hearing. By the way, one of the interesting points about their anechoic chambers is mention that if you sat in one, you could hear your heart beating (and this not just simply the blood pumping through veins near the ears - which are self canceling anyway). 73's Richard Clark, KB7QHC |
| All times are GMT +1. The time now is 09:54 AM. |
|
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com