I've often wondered this. If somebody speaks into your ear, you do not hear
the pop you often get on a microphone in the same position do you. Likewise
when listening to music in a hall with your ears and then over headphones
from a set of mikes you notice the echo on the latter but not on your ears.
People say its the way the brain processes the sound, but if that is the
case maybe now we can actually emulate this in some way for recording?
No I don't mean going back to a close miked up every single instrument and
a mixer you need to be Twizzle to operate.
Brian

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On Thu, 10 Aug 2017 11:22:47 +0100, "Brian Gaff"
wrote:

I've often wondered this. If somebody speaks into your ear, you do not hear
the pop you often get on a microphone in the same position do you. Likewise
when listening to music in a hall with your ears and then over headphones
from a set of mikes you notice the echo on the latter but not on your ears.
People say its the way the brain processes the sound, but if that is the
case maybe now we can actually emulate this in some way for recording?
No I don't mean going back to a close miked up every single instrument and
a mixer you need to be Twizzle to operate.
Brian

Ears are pressure transducers. This means that the ear drum almost
doesn't move when sound hits. A blast of air from a pop has very
little pressure, but a lot of velocity. Any microphone that isn't omni
will respond to air velocity - it is a combination of velocity and
pressure response that sets directivity. All pressure is omni, all
velocity is figure 8. A mixture of the two is one of the many flavours
of cardioid.

d

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Sometimes I wish I'd never asked.
OK then, I was under the impression that directivity was due to phase of
the wavefronts on both sides of a diaphragm. In the case of the ear, there
is only one clear side though. Also ears are log, and most amps are linear,
so I'd always assumed that it was the loudness ratio that caused the effect
in the ear and using headphones etc makes the ears perform differently.
Brian

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"Don Pearce" wrote in message
...
On Thu, 10 Aug 2017 11:22:47 +0100, "Brian Gaff"
wrote:

I've often wondered this. If somebody speaks into your ear, you do not
hear
the pop you often get on a microphone in the same position do you.
Likewise
when listening to music in a hall with your ears and then over headphones
from a set of mikes you notice the echo on the latter but not on your
ears.
People say its the way the brain processes the sound, but if that is the
case maybe now we can actually emulate this in some way for recording?
No I don't mean going back to a close miked up every single instrument
and
a mixer you need to be Twizzle to operate.
Brian

Ears are pressure transducers. This means that the ear drum almost
doesn't move when sound hits. A blast of air from a pop has very
little pressure, but a lot of velocity. Any microphone that isn't omni
will respond to air velocity - it is a combination of velocity and
pressure response that sets directivity. All pressure is omni, all
velocity is figure 8. A mixture of the two is one of the many flavours
of cardioid.

d

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On Thu, 10 Aug 2017 15:32:44 +0100, "Brian Gaff"
wrote:

Sometimes I wish I'd never asked.
OK then, I was under the impression that directivity was due to phase of
the wavefronts on both sides of a diaphragm. In the case of the ear, there
is only one clear side though. Also ears are log, and most amps are linear,
so I'd always assumed that it was the loudness ratio that caused the effect
in the ear and using headphones etc makes the ears perform differently.
Brian

Nope - none of that. Sorry. It is about phase, but also amplitude. The
velocity response of a mic - the figure 8 aspect - has a positive
phase for air approaching from the front, and obviously a negative
phase for sound from the back. It has an amplitude response that is
the Cos of the approach angle. Take the vector sum of the pressure
response, which is unity and constant phase all the way round, and the
velocity response which is as I just described, and you get a
cardioid. From the rear the pressure response and velocity response
are the same amplitude and opposite phase so they cancel.

And that is pretty much it.

d

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Brian Gaff wrote:

------------------------


OK then, I was under the impression that directivity was due to phase of
the wavefronts on both sides of a diaphragm.


** Correct.

A cardioid mic has openings that make the amplitude and phase of a sound the same on both sides of the diaphragm when arriving from the rear - resulting in no output. If the sound source moves to one side, a significant imbalance rises and the diaphragm moves accordingly.

A figure 8 mic has a null for sounds arriving at right angles to the diaphragm for the same reason.


...... Phil

Don Pearce wrote:

---------------------



Ears are pressure transducers. This means that the ear drum almost
doesn't move when sound hits.



** That is a non sequitur.

Ignoring proximity effect, diaphragms of omnidirectional (ie pressure) mics move the same amount as those of cardioids when exposed to the same sound. The cardioid has to be pointed at the source to get max output.

If the mic is a dynamic, excursion is inversely proportional to frequency cos output depends only on voice coil velocity.

If it is a condenser type, excursion is independent of frequency cos output depends only on diaphragm displacement.




A blast of air from a pop has very
little pressure, but a lot of velocity.

** But is not a sound at all.

See my other post in this thread.


..... Phil

On Thursday, 10 August 2017 13:22:52 UTC+3, Brian Gaff wrote:

No I don't mean going back to a close miked up every single instrument and
a mixer you need to be Twizzle to operate.
Brian

With the exception of classical, and some jazz recordings, close mic is and has been for many years, standard practice. One also adds "air mics" in a pair or Decca tree. So on a multitrack recording, 48 channels, each recorded close mic is by no means unusual.

Iain

On Thu, 10 Aug 2017 09:21:18 -0700 (PDT), Iain
wrote:

On Thursday, 10 August 2017 13:22:52 UTC+3, Brian Gaff wrote:

No I don't mean going back to a close miked up every single instrument and
a mixer you need to be Twizzle to operate.
Brian

With the exception of classical, and some jazz recordings, close mic is and has been for many years, standard practice. One also adds "air mics" in a pair or Decca tree. So on a multitrack recording, 48 channels, each recorded close mic is by no means unusual.

Iain

This pic of how the BBC handle St. John Smith Square is helpful. There
are two Blumlein pairs high above the orchestra, and a single spot mic
on the solo harpsichord. Just visible on the high balcony on the right
is one of the ambience mics.

https://www.gearslutz.com/board/atta...t_johns_01.jpg


In the past when I have been there, they have also had a Jecklin disc
a few yards behind the conductor. I'm betting they aren't going to use
the output from all of there, but tracks are cheap so why not record
them all?

d

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Well, I still find that recordings of orchestras with a pair of mikes sounds
more realistic. However in other situations, as some instruments are quiet
compared to others, I can see why they need close miking.

Also of course there is the background noise whether it be audio in a venue
or just hiss.
I have heard some awful Piano recordings where the his plays along as if a
noise gate is being used at a low level. Church organ recordings are often
very audio noisy, as one cannot move a church away from traffic and
sometimes the pump can be heard and with dodgy microphone placement the
chuffing noises are out of proportion to the notes.. Also of course both
piano and Organs have huge dynamic ranges.
With more popular recordings one obviously uses some compression. Some are
bad and you can hear it, others more sane and nice sounding!


However even some pop recordings from eh past made by emi, seem to have a
lot of problems with the pop effect, which were no obvious back in the day
on a scratchy 45!
Brian

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"Iain" wrote in message
...
On Thursday, 10 August 2017 13:22:52 UTC+3, Brian Gaff wrote:

No I don't mean going back to a close miked up every single instrument
and
a mixer you need to be Twizzle to operate.
Brian

With the exception of classical, and some jazz recordings, close mic is and
has been for many years, standard practice. One also adds "air mics" in a
pair or Decca tree. So on a multitrack recording, 48 channels, each
recorded close mic is by no means unusual.

Iain

On Friday, 11 August 2017 10:28:15 UTC+3, Brian Gaff wrote:
Well, I still find that recordings of orchestras with a pair of mikes sounds
more realistic. However in other situations, as some instruments are quiet
compared to others, I can see why they need close miking.

For orchestral realism, a pair, or tree is very good. The internal balance has to be right, but that's the responsibility of the conductor, A solo piano or harpsichord needs a spot mic to bring it into focus.

Multi microphone technique is particularly useful if you want a band recording with punch and presence. I can't imagine Thad Jones/Mel Lewis recorded with a pair of mics :-)))

Iain