• Reducing sound transmission to a mic.

    From amdx@21:1/5 to All on Sat Aug 13 19:47:17 2022
     Mounting a mic at the focus of a satellite dish want.
     I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the
    normal extended arm on a satellite dish.
     I want to sound isolate the Altoids tin from the upright extension it
    will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

                               Mikek

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to amdx on Sat Aug 13 23:10:29 2022
    On Saturday, August 13, 2022 at 5:47:27 PM UTC-7, amdx wrote:
    Mounting a mic at the focus of a satellite dish want.
    I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the
    normal extended arm on a satellite dish.
    I want to sound isolate the Altoids tin from the upright extension it
    will mount on.

    Add mass to the microphone, let the soft rubber and mass keep it from sonic-frequency acceleration. It might help to baffle the microphone's
    port to the dish, so eddy currents in sidewinds don't move the diaphragm.

    Your Altoids tin doesn't sit in FRONT of the microphone, so it doesn't really flex and send sound waves that matter. Microphones, with low-mass
    moving diaphragms, aren't accelerometer-sensitive.

    --- SoupGate-Win32 v1.05
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  • From Anthony Stewart@21:1/5 to amdx on Sun Aug 14 05:23:16 2022
    ".....On Saturday, 13 August 2022 at 20:47:27 UTC-4, amdx wrote:
    Mounting a mic at the focus of a satellite dish want.
    I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the normal extended arm on a satellite dish.

    The mounting is low pass with resonance with mass in damped springs for sonic attenuation and sub sonic position tracking. Old radio studio's used 4 corner springs undamped. Audio high gain will need to evaluation source of vibration and attenuation
    more carefully such as soft handle grips. Examine football remote mics.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From amdx@21:1/5 to amdx on Sun Aug 14 11:40:39 2022
    On 8/13/2022 7:47 PM, amdx wrote:
     Mounting a mic at the focus of a satellite dish want.
     I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the
    normal extended arm on a satellite dish.
     I want to sound isolate the Altoids tin from the upright extension it
    will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs
    of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

                               Mikek

      I got all working and found I hear the traffic so loud that I can't
    raise the
    gain high even off axis.
     Here is my working theory and please counter it if you know better.
     The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.
     I'm thinking the commercial poly-carbonate parabolic dishes do less of
    this, but it is a question.

    Is there a material that will vibrate less from ambient sound and be
    highly reflective?
                                         Mikek

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to amdx on Sun Aug 14 17:55:34 2022
    amdx <amdx@knology.net> wrote:

    On 8/13/2022 7:47 PM, amdx wrote:
     Mounting a mic at the focus of a satellite dish want.
     I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the normal extended arm on a satellite dish.
     I want to sound isolate the Altoids tin from the upright extension it will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs
    of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

                               Mikek

      I got all working and found I hear the traffic so loud that I can't
    raise the
    gain high even off axis.
     Here is my working theory and please counter it if you know better.
     The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.
     I'm thinking the commercial poly-carbonate parabolic dishes do less of this, but it is a question.

    Is there a material that will vibrate less from ambient sound and be
    highly reflective?
                           Mikek

    The BBC used to back their metal dishes with a thick layer of felt - in particular this was to reduce the noise of raindrops hitting the dish
    but it also reduced 'ringing' of the metal. A number of patches of
    bituminised roofing felt, stuck on with flexible solvent glue
    (Evo-Stick), covering about 50% of the total area, should be enough to
    deaden the ringing effect of your dish.

    A wind cover for the mic needs to have a space between the outer
    covering and the mic itself, otherwise wind penetrating the base layer
    of the fur (or whatever you use) will produce a pressure change directly
    on the diaphragm. With a decent gap, the penetrating air can circulate
    gently and harmlessly. The easiest way to achive this is to use a large conventional open foam 'pop' shield covered with a furry sock - don't
    rely on the sock alone.

    [How to make one for a Tascam DR-05: http://www.poppyrecords.co.uk/other/poileuse/poileuse.php
    modify as required.]

    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to amdx on Sun Aug 14 18:37:35 2022
    amdx <amdx@knology.net> wrote:

    On 8/13/2022 7:47 PM, amdx wrote:
     Mounting a mic at the focus of a satellite dish want.
     I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the normal extended arm on a satellite dish.
     I want to sound isolate the Altoids tin from the upright extension it will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs
    of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

                               Mikek

      I got all working and found I hear the traffic so loud that I can't
    raise the
    gain high even off axis.

    Are you only hearing the low frequency component of the traffic noise?
    A dish will give no directional effect at all at low frequencies.

    If you want to produce a directional effect as low as (for example)
    250c/s you will need a dish whose diameter is in the region of 4ft
    diameter.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Joe Gwinn@21:1/5 to Liz Tuddenham on Sun Aug 14 14:03:06 2022
    On Sun, 14 Aug 2022 17:55:34 +0100, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    amdx <amdx@knology.net> wrote:

    On 8/13/2022 7:47 PM, amdx wrote:
     Mounting a mic at the focus of a satellite dish want.
     I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the
    normal extended arm on a satellite dish.
     I want to sound isolate the Altoids tin from the upright extension it
    will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs
    of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

                               Mikek

      I got all working and found I hear the traffic so loud that I can't
    raise the
    gain high even off axis.
     Here is my working theory and please counter it if you know better.
     The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.
     I'm thinking the commercial poly-carbonate parabolic dishes do less of
    this, but it is a question.

    Is there a material that will vibrate less from ambient sound and be
    highly reflective?
                           Mikek

    The BBC used to back their metal dishes with a thick layer of felt - in >particular this was to reduce the noise of raindrops hitting the dish
    but it also reduced 'ringing' of the metal. A number of patches of >bituminised roofing felt, stuck on with flexible solvent glue
    (Evo-Stick), covering about 50% of the total area, should be enough to
    deaden the ringing effect of your dish.

    This has almost achieved a constrained-layer damper, which would be a
    large improvement. Just glue an outer metal foil layer, so the
    tar-felt is in the middle.

    .<https://en.wikipedia.org/wiki/Constrained-layer_damping>

    The linked masters thesis has much detail, and is open.

    .<https://vtechworks.lib.vt.edu/handle/10919/35350>

    "Passive Viscoelastic Constrained Layer Damping Application for a
    Small Aircraft Landing Gear System"

    Joe Gwinn

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From amdx@21:1/5 to Joe Gwinn on Sun Aug 14 13:35:57 2022
    On 8/14/2022 1:03 PM, Joe Gwinn wrote:
    On Sun, 14 Aug 2022 17:55:34 +0100, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    amdx <amdx@knology.net> wrote:

    On 8/13/2022 7:47 PM, amdx wrote:
     Mounting a mic at the focus of a satellite dish want.
     I have a mic connected to an Altoids tin, I have the mic mounted in >>>> soft rubber.
    The tin will be mounted to an upright extension that is mounted to the >>>> normal extended arm on a satellite dish.
     I want to sound isolate the Altoids tin from the upright extension it >>>> will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs
    of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

                               Mikek
      I got all working and found I hear the traffic so loud that I can't >>> raise the
    gain high even off axis.
     Here is my working theory and please counter it if you know better. >>>  The metal satellite dish picks up ambient sound from all directions >>> and re-radiates though the air to the mic.
     I'm thinking the commercial poly-carbonate parabolic dishes do less of
    this, but it is a question.

    Is there a material that will vibrate less from ambient sound and be
    highly reflective?
                           Mikek
    The BBC used to back their metal dishes with a thick layer of felt - in
    particular this was to reduce the noise of raindrops hitting the dish
    but it also reduced 'ringing' of the metal. A number of patches of
    bituminised roofing felt, stuck on with flexible solvent glue
    (Evo-Stick), covering about 50% of the total area, should be enough to
    deaden the ringing effect of your dish.

    This has almost achieved a constrained-layer damper, which would be a
    large improvement. Just glue an outer metal foil layer, so the
    tar-felt is in the middle.

    .<https://en.wikipedia.org/wiki/Constrained-layer_damping>

    The linked masters thesis has much detail, and is open.

    .<https://vtechworks.lib.vt.edu/handle/10919/35350>

    "Passive Viscoelastic Constrained Layer Damping Application for a
    Small Aircraft Landing Gear System"

    Joe Gwinn
    That's interesting, I have couple of tar like substances on a substrate.
    Peal and stick for roofs. And also a thicker 6" wide sealing tape.
     If I get energetic I'll set my phone sinewave generator off axis at 1000Hz and measure, then apply and measure again to see if it cuts it down.
                           Thanks, Mikek

    --- SoupGate-Win32 v1.05
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  • From Don Y@21:1/5 to amdx on Sun Aug 14 11:54:53 2022
    On 8/14/2022 9:40 AM, amdx wrote:
    I got all working and found I hear the traffic so loud that I can't raise the
    gain high even off axis.

    Think of the geometry involved. The sounds you are (presumably) interested in are (more or less) "behind" the dish-facing microphone. You can recess the microphone in a "cup" that works to attenuate sources coming in from the side but not interfering with the reflected sounds being FOCUSED on the microphone. The dimensions of that cup depend on the size of the dish and how much you want to "select".

    You will always hear the undesirable sounds. What you are hoping to do
    is amplify the sounds you are focused on.

    The whispering gallery at the Museum of Science and Industry illustrates this dramatically.

    <https://www.msichicago.org/explore/whats-here/exhibits/whispering-gallery/>

    Standing at a focus, you can clearly hear those folks around you -- at NORMAL volume levels. The "magic" comes from the fact that you can hear the
    speaker at the far (30 ft?) focus WHISPERING just as clearly.

    [Amusing to see math actually work, eh? Similar issues in the design of theatrical lighting...]


    Here is my working theory and please counter it if you know better.
    The metal satellite dish picks up ambient sound from all directions and re-radiates though the air to the mic.
    I'm thinking the commercial poly-carbonate parabolic dishes do less of this,
    but it is a question.

    Is there a material that will vibrate less from ambient sound and be highly reflective?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From amdx@21:1/5 to Don Y on Sun Aug 14 14:55:39 2022
    On 8/14/2022 1:54 PM, Don Y wrote:
    On 8/14/2022 9:40 AM, amdx wrote:
       I got all working and found I hear the traffic so loud that I
    can't raise the
    gain high even off axis.

    Think of the geometry involved.  The sounds you are (presumably)
    interested in
    are (more or less) "behind" the dish-facing microphone.  You can
    recess the microphone in a "cup" that works to attenuate sources
    coming in from the side
    but not interfering with the reflected sounds being FOCUSED on the microphone.
    The dimensions of that cup depend on the size of the dish and how much
    you want
    to "select".

    You will always hear the undesirable sounds.  What you are hoping to do
    is amplify the sounds you are focused on.

    The whispering gallery at the Museum of Science and Industry
    illustrates this
    dramatically.

    <https://www.msichicago.org/explore/whats-here/exhibits/whispering-gallery/>


    Standing at a focus, you can clearly hear those folks around you -- at
    NORMAL
    volume levels.  The "magic" comes from the fact that you can hear the speaker at the far (30 ft?) focus WHISPERING just as clearly.

    [Amusing to see math actually work, eh?  Similar issues in the design of theatrical lighting...]


      Here is my working theory and please counter it if you know better.
      The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.
      I'm thinking the commercial poly-carbonate parabolic dishes do less
    of this, but it is a question.

    Is there a material that will vibrate less from ambient sound and be
    highly reflective?

    I'm looking at some cheap ABS reflectors, the may be shape in question.
    How much does that matter?
    All Amazon Links, some very long so I tinyurled them.
     Your opinion on what may work best. Thanks, Mikek

    Here's a 16", a little flat at the center.
    https://www.amazon.com/Perky-Pet-340-Transparent-16-Inch-Squirrel/dp/B0006G52ME/ref=sr_1_6?keywords=squirrel+baffle+plastic&qid=1660504956&sr=8-6

    Here is a 12", it has a constant shape.
    https://tinyurl.com/2b9vknvp

    Here is a 13" with extended sides, That may put the mic within the
    edges, that might be a good thing.

    And a 10".
    https://tinyurl.com/427w4nxr

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to amdx on Sun Aug 14 13:33:07 2022
    On 8/14/2022 12:55 PM, amdx wrote:
    On 8/14/2022 1:54 PM, Don Y wrote:
    On 8/14/2022 9:40 AM, amdx wrote:
    I got all working and found I hear the traffic so loud that I can't raise
    the
    gain high even off axis.

    Think of the geometry involved. The sounds you are (presumably) interested in
    are (more or less) "behind" the dish-facing microphone. You can recess the >> microphone in a "cup" that works to attenuate sources coming in from the side
    but not interfering with the reflected sounds being FOCUSED on the microphone.
    The dimensions of that cup depend on the size of the dish and how much you want
    to "select".

    You will always hear the undesirable sounds. What you are hoping to do
    is amplify the sounds you are focused on.

    The whispering gallery at the Museum of Science and Industry illustrates this
    dramatically.

    <https://www.msichicago.org/explore/whats-here/exhibits/whispering-gallery/> >>
    Standing at a focus, you can clearly hear those folks around you -- at NORMAL
    volume levels. The "magic" comes from the fact that you can hear the
    speaker at the far (30 ft?) focus WHISPERING just as clearly.

    [Amusing to see math actually work, eh? Similar issues in the design of
    theatrical lighting...]


    Here is my working theory and please counter it if you know better.
    The metal satellite dish picks up ambient sound from all directions and >>> re-radiates though the air to the mic.
    I'm thinking the commercial poly-carbonate parabolic dishes do less of >>> this, but it is a question.

    Is there a material that will vibrate less from ambient sound and be highly >>> reflective?

    I'm looking at some cheap ABS reflectors, the may be shape in question. How much does that matter?

    <shrug> There are lots of factors that will influence the overall result.
    And, this isn't my field of expertise.

    I'd go to the nearest "dollar store" and pick up some cheap plastic
    cups/bowls and try them on for size. Something sturdier than a
    tupperware container. A file can make quick work of "adjusting" its
    size. (and, at < $1/each, you can afford to experiment)

    Draw a parabola (or find an online image). Notice the paths the
    distant rays follow to the focus. The deeper the cup, the more
    the peripheral rays are excluded (the less "collector area"
    comes to your aid). If your dish is fairly "flat" (focus
    well above the sides of the dish), then those peripheral rays
    are already not being caught -- so you can afford a deeper cup.

    OTOH, a deeper dish (focus closer to the dish than the outermost edge)
    means there is a benefit to those peripheral rays. And, also less
    need to shield the side of the microphone as the "high walls" of the
    dish are already doing some of that for you.

    Notice how shallow/small the reflector in the Whispering Gallery.
    The listener FACES the clear reflector, his back to the other
    listener's back. His ears relatively exposed to people walking
    past him. But, very little *gain* from those sound sources.

    I think the biggest win (for a portable mic) comes from having a deep
    parabola for your dish -- so the focus is more "shielded" from sound/wind blowing across the microphone. Maximize gain for the "sought signal"
    and hope the ambient doesn't overwhelm.

    Play. It's a fun project. Little chance of injury, damage, etc.
    The dish is the most precious item -- and I suspect you can find
    several of them listed on CL if you were really interested (or,
    neighbors who are no longer using theirs)

    I did this when a kid. But, the sounds I was after were distant with
    few other sound sources competing. E.g., listening to things off in
    the woods or across a field. I didn't discover cars and traffic until
    much later in life :<

    All Amazon Links, some very long so I tinyurled them.
    Your opinion on what may work best. Thanks, Mikek

    Here's a 16", a little flat at the center.
    https://www.amazon.com/Perky-Pet-340-Transparent-16-Inch-Squirrel/dp/B0006G52ME/ref=sr_1_6?keywords=squirrel+baffle+plastic&qid=1660504956&sr=8-6


    Here is a 12", it has a constant shape.
    https://tinyurl.com/2b9vknvp

    Here is a 13" with extended sides, That may put the mic within the edges, that
    might be a good thing.

    And a 10".
    https://tinyurl.com/427w4nxr


    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From amdx@21:1/5 to Don Y on Sun Aug 14 16:32:28 2022
    On 8/14/2022 3:33 PM, Don Y wrote:
    On 8/14/2022 12:55 PM, amdx wrote:
    On 8/14/2022 1:54 PM, Don Y wrote:
    On 8/14/2022 9:40 AM, amdx wrote:
       I got all working and found I hear the traffic so loud that I
    can't raise the
    gain high even off axis.

    Think of the geometry involved.  The sounds you are (presumably)
    interested in
    are (more or less) "behind" the dish-facing microphone.  You can
    recess the microphone in a "cup" that works to attenuate sources
    coming in from the side
    but not interfering with the reflected sounds being FOCUSED on the
    microphone.
    The dimensions of that cup depend on the size of the dish and how
    much you want
    to "select".

    You will always hear the undesirable sounds.  What you are hoping to do >>> is amplify the sounds you are focused on.

    The whispering gallery at the Museum of Science and Industry
    illustrates this
    dramatically.

    <https://www.msichicago.org/explore/whats-here/exhibits/whispering-gallery/>


    Standing at a focus, you can clearly hear those folks around you --
    at NORMAL
    volume levels.  The "magic" comes from the fact that you can hear the
    speaker at the far (30 ft?) focus WHISPERING just as clearly.

    [Amusing to see math actually work, eh?  Similar issues in the
    design of
    theatrical lighting...]


      Here is my working theory and please counter it if you know better. >>>>   The metal satellite dish picks up ambient sound from all
    directions and re-radiates though the air to the mic.
      I'm thinking the commercial poly-carbonate parabolic dishes do
    less of this, but it is a question.

    Is there a material that will vibrate less from ambient sound and
    be highly reflective?

    I'm looking at some cheap ABS reflectors, the may be shape in
    question. How much does that matter?

    <shrug>  There are lots of factors that will influence the overall
    result.
    And, this isn't my field of expertise.

    I'd go to the nearest "dollar store" and pick up some cheap plastic cups/bowls and try them on for size.  Something sturdier than a
    tupperware container.  A file can make quick work of "adjusting" its
    size.  (and, at < $1/each, you can afford to experiment)

    Draw a parabola (or find an online image).  Notice the paths the
    distant rays follow to the focus.  The deeper the cup, the more
    the peripheral rays are excluded (the less "collector area"
    comes to your aid).  If your dish is fairly "flat" (focus
    well above the sides of the dish), then those peripheral rays
    are already not being caught -- so you can afford a deeper cup.

    OTOH, a deeper dish (focus closer to the dish than the outermost edge)
    means there is a benefit to those peripheral rays.  And, also less
    need to shield the side of the microphone as the "high walls" of the
    dish are already doing some of that for you.

    Notice how shallow/small the reflector in the Whispering Gallery.
    The listener FACES the clear reflector, his back to the other
    listener's back.  His ears relatively exposed to people walking
    past him.  But, very little *gain* from those sound sources.

    I think the biggest win (for a portable mic) comes from having a deep parabola for your dish -- so the focus is more "shielded" from sound/wind blowing across the microphone.  Maximize gain for the "sought signal"
    and hope the ambient doesn't overwhelm.

    Play.  It's a fun project.  Little chance of injury, damage, etc.
    The dish is the most precious item -- and I suspect you can find
    several of them listed on CL if you were really interested (or,
    neighbors who are no longer using theirs)

    I did this when a kid.  But, the sounds I was after were distant with
    few other sound sources competing.  E.g., listening to things off in
    the woods or across a field.  I didn't discover cars and traffic until
    much later in life  :<

    All Amazon Links, some very long so I tinyurled them.
      Your opinion on what may work best. Thanks, Mikek

    Here's a 16", a little flat at the center.
    https://www.amazon.com/Perky-Pet-340-Transparent-16-Inch-Squirrel/dp/B0006G52ME/ref=sr_1_6?keywords=squirrel+baffle+plastic&qid=1660504956&sr=8-6


    Here is a 12", it has a constant shape.
    https://tinyurl.com/2b9vknvp

    Here is a 13" with extended sides, That may put the mic within the
    edges, that might be a good thing.

    And a 10".
    https://tinyurl.com/427w4nxr


    Oh, I see I missed the link for the extended side reflector.
    https://www.amazon.com/Myard-Wobbly-Squirrel-Baffle-Deflector/dp/B07HCCX5D6/ref=sr_1_30?crid=35IAGKWXKWQJB&keywords=squirrel+baffle+plastic&qid=1660505201&sprefix=%2Caps%2C387&sr=8-30
    For those that didn't want to click all the lengths, I put all 4 shapes
    in on picture and put it on drop box.
    https://www.dropbox.com/s/zxaspkx9m92bbxc/Shape%201.jpg?dl=0

                                   Mikek

    --- SoupGate-Win32 v1.05
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  • From Jan Panteltje@21:1/5 to amdx@knology.net on Mon Aug 15 05:36:44 2022
    On a sunny day (Sun, 14 Aug 2022 14:55:39 -0500) it happened amdx <amdx@knology.net> wrote in <tdbjvu$38g2f$1@dont-email.me>:


      Here is my working theory and please counter it if you know better.
      The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.
      I'm thinking the commercial poly-carbonate parabolic dishes do less
    of this, but it is a question.

    Is there a material that will vibrate less from ambient sound and be
    highly reflective?

    The thread about laser range findings recalled the discussions about
    using the time variations from a laser reflected from a window to monitor audio in a room.
    (from vibrating glass)

    If you could point it at somebodies throat and pick up sound like old throat mikes....
    Maybe the red spot would freak them out...
    Use IR perhaps.. camera for pointing, could be a fun project.
    Or point at something in the vicinity, cardboard boxes, screens, what not.

    Its old tech that could be taken as start point for a better spy system.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jasen Betts@21:1/5 to amdx on Mon Aug 15 10:59:19 2022
    On 2022-08-14, amdx <amdx@knology.net> wrote:
    On 8/13/2022 7:47 PM, amdx wrote:
     Mounting a mic at the focus of a satellite dish want.
     I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the
    normal extended arm on a satellite dish.
     I want to sound isolate the Altoids tin from the upright extension it
    will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs
    of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

                               Mikek

      I got all working and found I hear the traffic so loud that I can't
    raise the
    gain high even off axis.
     Here is my working theory and please counter it if you know better.
     The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.

    If it's ringing the sound waves won't be normal to the dish but at
    some angle determined by the wave propogation speed ratios.
    also most of the dish is not normal to the microphone, but much of it
    is probably close enough.

     I'm thinking the commercial poly-carbonate parabolic dishes do less of this, but it is a question.

    Is there a material that will vibrate less from ambient sound and be
    highly reflective?

    Steel satellite dish with sound deadening material (from automiobile parts shop)
    stuck on the back, or the nucelar option: concrete (as thick as you care to make it)

    --
    Jasen.

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  • From amdx@21:1/5 to Jasen Betts on Mon Aug 15 06:55:17 2022
    On 8/15/2022 5:59 AM, Jasen Betts wrote:
    On 2022-08-14, amdx <amdx@knology.net> wrote:
    On 8/13/2022 7:47 PM, amdx wrote:
     Mounting a mic at the focus of a satellite dish want.
     I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the
    normal extended arm on a satellite dish.
     I want to sound isolate the Altoids tin from the upright extension it >>> will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs
    of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

                               Mikek
      I got all working and found I hear the traffic so loud that I can't
    raise the
    gain high even off axis.
     Here is my working theory and please counter it if you know better.
     The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.
    If it's ringing the sound waves won't be normal to the dish but at
    some angle determined by the wave propogation speed ratios.
    also most of the dish is not normal to the microphone, but much of it
    is probably close enough.

     I'm thinking the commercial poly-carbonate parabolic dishes do less of >> this, but it is a question.
    Is there a material that will vibrate less from ambient sound and be
    highly reflective?
    Steel satellite dish with sound deadening material (from automiobile parts shop)
    stuck on the back, or the nucelar option: concrete (as thick as you care to make it)

    In early testing of noise from a couple different pre amps, I surrounded
    my mic
    in a sheet of lead rolled into a tube with sealed ends. This worked very
    well!
    This eliminated traffic noise that I could hear through the headphones
    while inside my house.
    I wonder if I could roll a cone of lead to shield the mic from some of
    the off axis ambient noise?
                                                 Mikek

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  • From a a@21:1/5 to amdx on Mon Aug 15 05:08:00 2022
    On Monday, 15 August 2022 at 13:55:26 UTC+2, amdx wrote:
    On 8/15/2022 5:59 AM, Jasen Betts wrote:
    On 2022-08-14, amdx <am...@knology.net> wrote:
    On 8/13/2022 7:47 PM, amdx wrote:
    Mounting a mic at the focus of a satellite dish want.
    I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the >>> normal extended arm on a satellite dish.
    I want to sound isolate the Altoids tin from the upright extension it >>> will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs
    of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

    Mikek
    I got all working and found I hear the traffic so loud that I can't
    raise the
    gain high even off axis.
    Here is my working theory and please counter it if you know better.
    The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.
    If it's ringing the sound waves won't be normal to the dish but at
    some angle determined by the wave propogation speed ratios.
    also most of the dish is not normal to the microphone, but much of it
    is probably close enough.

    I'm thinking the commercial poly-carbonate parabolic dishes do less of
    this, but it is a question.
    Is there a material that will vibrate less from ambient sound and be
    highly reflective?
    Steel satellite dish with sound deadening material (from automiobile parts shop)
    stuck on the back, or the nucelar option: concrete (as thick as you care to make it)

    In early testing of noise from a couple different pre amps, I surrounded
    my mic
    in a sheet of lead rolled into a tube with sealed ends. This worked very well!
    This eliminated traffic noise that I could hear through the headphones
    while inside my house.
    I wonder if I could roll a cone of lead to shield the mic from some of
    the off axis ambient noise?
    Mikek
    have you tried 4 mics background noise filtering out concept known from Kinect

    https://qph.cf2.quoracdn.net/main-qimg-3a6efb532cf8ce709a3f14c8b96b3661-pjlq

    How does Microsoft's Kinect work from a technology standpoint?

    https://www.quora.com/How-does-Microsofts-Kinect-work-from-a-technology-standpoint

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  • From John Walliker@21:1/5 to amdx on Mon Aug 15 06:36:48 2022
    On Monday, 15 August 2022 at 12:55:26 UTC+1, amdx wrote:
    On 8/15/2022 5:59 AM, Jasen Betts wrote:
    On 2022-08-14, amdx <am...@knology.net> wrote:
    On 8/13/2022 7:47 PM, amdx wrote:
    Mounting a mic at the focus of a satellite dish want.
    I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the >>> normal extended arm on a satellite dish.
    I want to sound isolate the Altoids tin from the upright extension it >>> will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs
    of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

    Mikek
    I got all working and found I hear the traffic so loud that I can't
    raise the
    gain high even off axis.
    Here is my working theory and please counter it if you know better.
    The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.
    If it's ringing the sound waves won't be normal to the dish but at
    some angle determined by the wave propogation speed ratios.
    also most of the dish is not normal to the microphone, but much of it
    is probably close enough.

    I'm thinking the commercial poly-carbonate parabolic dishes do less of
    this, but it is a question.
    Is there a material that will vibrate less from ambient sound and be
    highly reflective?
    Steel satellite dish with sound deadening material (from automiobile parts shop)
    stuck on the back, or the nucelar option: concrete (as thick as you care to make it)

    In early testing of noise from a couple different pre amps, I surrounded
    my mic
    in a sheet of lead rolled into a tube with sealed ends. This worked very well!
    This eliminated traffic noise that I could hear through the headphones
    while inside my house.
    I wonder if I could roll a cone of lead to shield the mic from some of
    the off axis ambient noise?
    Mikek

    That will only help at high frequencies. Are you still using an omni-directional mic?
    You might get better results if you use a mic with a cardioid response and point the
    most sensitive direction at the dish.
    John

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  • From Ricky@21:1/5 to amdx on Mon Aug 15 10:04:57 2022
    On Monday, August 15, 2022 at 7:55:26 AM UTC-4, amdx wrote:
    On 8/15/2022 5:59 AM, Jasen Betts wrote:
    On 2022-08-14, amdx <am...@knology.net> wrote:
    On 8/13/2022 7:47 PM, amdx wrote:
    Mounting a mic at the focus of a satellite dish want.
    I have a mic connected to an Altoids tin, I have the mic mounted in
    soft rubber.
    The tin will be mounted to an upright extension that is mounted to the >>> normal extended arm on a satellite dish.
    I want to sound isolate the Altoids tin from the upright extension it >>> will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs
    of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

    Mikek
    I got all working and found I hear the traffic so loud that I can't
    raise the
    gain high even off axis.
    Here is my working theory and please counter it if you know better.
    The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.
    If it's ringing the sound waves won't be normal to the dish but at
    some angle determined by the wave propogation speed ratios.
    also most of the dish is not normal to the microphone, but much of it
    is probably close enough.

    I'm thinking the commercial poly-carbonate parabolic dishes do less of >> this, but it is a question.
    Is there a material that will vibrate less from ambient sound and be
    highly reflective?
    Steel satellite dish with sound deadening material (from automiobile parts shop)
    stuck on the back, or the nucelar option: concrete (as thick as you care to make it)

    In early testing of noise from a couple different pre amps, I surrounded
    my mic
    in a sheet of lead rolled into a tube with sealed ends. This worked very well!
    This eliminated traffic noise that I could hear through the headphones
    while inside my house.
    I wonder if I could roll a cone of lead to shield the mic from some of
    the off axis ambient noise?
    Mikek

    I think the way parabolic mics work is to overwhelm the stray noise with the gain of the on axis sounds. If you are still hearing ambient noise you can try a bigger reflector. Remember, the area of the reflector goes up with the square of the diameter.


    You can also filter the lower frequencies since they are not important to many uses.

    In sonar work, they use what is called beam forming. This involves the use of many microphones and signal processing, to reduce the amplitude of signals arriving off axis. This can easily eliminate sounds from any direction, including from the rear of
    the sensor array. If you don't need for it to be mobile, it can work at any frequency range you want. Picture a four foot square sheet of thin plywood, with tiny, electret mics on a 2 inch grid, or 24^2 or 576 mics. Wow! That's a lot of microphones!
    I guess that's why submarine sonar systems cost so much!
    Anyway, each mic would need a small amp with band pass filtering and an ADC input. They have ADCs with up to 16 inputs each.

    The spacing of the mics set the highest frequency in use and the aggregate size sets the lowest frequency. The numbers I picked were for the full range of speech, 300 Hz to 3,300 Hz. The number of sensors can be reduced by changing these numbers. It
    might be possible to make the array 1 dimensional if aiming vertically is not important. That would reduce your mic count a lot.

    --

    Rick C.

    - Get 1,000 miles of free Supercharging
    - Tesla referral code - https://ts.la/richard11209

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  • From John Walliker@21:1/5 to Ricky on Mon Aug 15 11:42:14 2022
    On Monday, 15 August 2022 at 18:05:01 UTC+1, Ricky wrote:
    On Monday, August 15, 2022 at 7:55:26 AM UTC-4, amdx wrote:
    On 8/15/2022 5:59 AM, Jasen Betts wrote:
    On 2022-08-14, amdx <am...@knology.net> wrote:
    On 8/13/2022 7:47 PM, amdx wrote:
    Mounting a mic at the focus of a satellite dish want.
    I have a mic connected to an Altoids tin, I have the mic mounted in >>> soft rubber.
    The tin will be mounted to an upright extension that is mounted to the >>> normal extended arm on a satellite dish.
    I want to sound isolate the Altoids tin from the upright extension it >>> will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs >>> of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

    Mikek
    I got all working and found I hear the traffic so loud that I can't
    raise the
    gain high even off axis.
    Here is my working theory and please counter it if you know better.
    The metal satellite dish picks up ambient sound from all directions
    and re-radiates though the air to the mic.
    If it's ringing the sound waves won't be normal to the dish but at
    some angle determined by the wave propogation speed ratios.
    also most of the dish is not normal to the microphone, but much of it
    is probably close enough.

    I'm thinking the commercial poly-carbonate parabolic dishes do less of >> this, but it is a question.
    Is there a material that will vibrate less from ambient sound and be
    highly reflective?
    Steel satellite dish with sound deadening material (from automiobile parts shop)
    stuck on the back, or the nucelar option: concrete (as thick as you care to make it)

    In early testing of noise from a couple different pre amps, I surrounded my mic
    in a sheet of lead rolled into a tube with sealed ends. This worked very well!
    This eliminated traffic noise that I could hear through the headphones while inside my house.
    I wonder if I could roll a cone of lead to shield the mic from some of
    the off axis ambient noise?
    Mikek
    I think the way parabolic mics work is to overwhelm the stray noise with the gain of the on axis sounds. If you are still hearing ambient noise you can try a bigger reflector. Remember, the area of the reflector goes up with the square of the diameter.

    You can also filter the lower frequencies since they are not important to many uses.

    In sonar work, they use what is called beam forming. This involves the use of many microphones and signal processing, to reduce the amplitude of signals arriving off axis. This can easily eliminate sounds from any direction, including from the rear of
    the sensor array. If you don't need for it to be mobile, it can work at any frequency range you want. Picture a four foot square sheet of thin plywood, with tiny, electret mics on a 2 inch grid, or 24^2 or 576 mics. Wow! That's a lot of microphones! I
    guess that's why submarine sonar systems cost so much!
    Anyway, each mic would need a small amp with band pass filtering and an ADC input. They have ADCs with up to 16 inputs each.

    The spacing of the mics set the highest frequency in use and the aggregate size sets the lowest frequency. The numbers I picked were for the full range of speech, 300 Hz to 3,300 Hz. The number of sensors can be reduced by changing these numbers. It
    might be possible to make the array 1 dimensional if aiming vertically is not important. That would reduce your mic count a lot.

    Here is a paper from 1976 on the subject: https://www.sciencedirect.com/science/article/abs/pii/0022460X76905526

    John

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  • From Martin Brown@21:1/5 to amdx on Mon Aug 15 20:35:03 2022
    On 14/08/2022 19:35, amdx wrote:
    On 8/14/2022 1:03 PM, Joe Gwinn wrote:
    On Sun, 14 Aug 2022 17:55:34 +0100, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    amdx <amdx@knology.net> wrote:

    On 8/13/2022 7:47 PM, amdx wrote:
     Mounting a mic at the focus of a satellite dish want.
     I have a mic connected to an Altoids tin, I have the mic mounted in >>>>> soft rubber.
    The tin will be mounted to an upright extension that is mounted to the >>>>> normal extended arm on a satellite dish.
     I want to sound isolate the Altoids tin from the upright
    extension it
    will mount on.
    Does silicone have low sound transmission? I'm thinking about 4 dabs >>>>> of silicone about 1/4" tall,
    in the corners on the underside of the Altoid tin.

    Does low sound transmission mean the same as high dampening?

                               Mikek
        I got all working and found I hear the traffic so loud that I
    can't
    raise the
    gain high even off axis.
       Here is my working theory and please counter it if you know better. >>>>    The metal satellite dish picks up ambient sound from all directions >>>> and re-radiates though the air to the mic.
       I'm thinking the commercial poly-carbonate parabolic dishes do
    less of
    this, but it is a question.

    Is there a material that will vibrate less from ambient sound and be
    highly reflective?
                             Mikek
    The BBC used to back their metal dishes with a thick layer of felt - in
    particular this was to reduce the noise of raindrops hitting the dish
    but it also reduced 'ringing' of the metal.  A number of patches of
    bituminised roofing felt, stuck on with flexible solvent glue
    (Evo-Stick), covering about 50% of the total area, should be enough to
    deaden the ringing effect of your dish.

    This has almost achieved a constrained-layer damper, which would be a
    large improvement.  Just glue an outer metal foil layer, so the
    tar-felt is in the middle.

    .<https://en.wikipedia.org/wiki/Constrained-layer_damping>

    The linked masters thesis has much detail, and is open.

    .<https://vtechworks.lib.vt.edu/handle/10919/35350>

    "Passive Viscoelastic Constrained Layer Damping Application for a
    Small Aircraft Landing Gear System"

    Joe Gwinn
    That's interesting, I have couple of tar like substances on a substrate.
    Peal and stick for roofs. And also a thicker 6" wide sealing tape.
     If I get energetic I'll set my phone sinewave generator off axis at
    1000Hz
    and measure, then apply and measure again to see if it cuts it down.
                           Thanks, Mikek

    The stuff you want to back the reflector with is an acoustic foam sold
    in small pieces for making PCs much quieter and in large pieces for
    recording studios. It is essentially a moderately dense flexible foam
    with a thin slab of rubber in the middle. The latter absorbs most of the coherent sound energy and the foam then dissipates it. Metal boxes and
    sheets that would otherwise ring like a bell can be almost completely
    silenced by applying it.

    Silicone gaskets in just the right places can help a lot too.

    There is always a trade off between weight and effectiveness. The
    commercial products intended for acoustic management are very close to
    optimal since it is their business to be effective in minimal space.

    --
    Regards,
    Martin Brown

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  • From whit3rd@21:1/5 to Martin Brown on Mon Aug 15 16:34:12 2022
    On Monday, August 15, 2022 at 12:35:17 PM UTC-7, Martin Brown wrote:

    On 8/13/2022 7:47 PM, amdx wrote:
    Â Mounting a mic at the focus of a satellite dish ...
    Is there a material that will vibrate less from ambient sound and be >>>> highly reflective?

    The stuff you want to back the reflector with is an acoustic foam sold
    in small pieces for making PCs much quieter and in large pieces for recording studios.

    Patches of the stuff are commonly applied to stainless sinks to keep 'em
    from making a racket. But, since the original poster has a focusing dish,
    the modes that would 'ring' that dish really don't focus on his microphone. Probably the dish isn't causing a problem, rather the 'road noise' could be rushing sounds, i.e. turbulence due to winds. For that, you put a sock on it...

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