The Radiation Pattern of Instruments

[Ron Resnick]

On a different thread microstrip referred to "reproducing as much as possible the radiation pattern of the instrument" (emphasis added). I see interesting questions here!

What are the radiation patterns of different instruments? (In the hobby of amateur radio we see depicted frequently the radiation patterns of antennas.)

What is the radiation pattern of the human voice?

How do different speaker designs -- dynamic driver box speakers versus full-range ribbon speakers versus electrostatic speakers -- handle the recreation of the original radiation pattern of the instruments?

Would the answers to these questions suggest that some speaker designs are better suited to reproducing certain instruments than other speaker designs?

 

[Kal Rubinson]

I think the radiation pattern of instruments and voices is more an issue for the recordist and not for playback.

 

[FrantzM]

Hi

IMHO. There is no way to reproduce the radiation patterns of instruments within current recording and reproduction technology. There may be some happenstances in which such may occur but it will be exceedingy rare and fleeting. Even if it were to happen for one instrument it wouldn't work for another

 

[treitz3]

Agreed Frantz.

Tom

 

[DonH50]

It depends upon the instrument. I don't have studies off-hand, but off-the-cuff:

• Brass instruments radiate out the bell, with dispersion dictated by bell taper. Note French horns' bells point "backwards" so you get reflected sound.
• Strings radiate from sounding holes (if any) and directly from the strings as they are plucked/bowed/strummed/whatever.
• Most reeds radiate from the opening of the instrument, e.g. "bell" end of a clarinet. Some radiate from the top (bassoon), some from the bottom (clarinet, oboe), and there is some direct radiation from the reed though it is usually small.
• Flutes radiate from the embouchure hole on the lip plate and out the end of the tube. (Solo flutes often use two mics to capture both.)
• Piano radiates from the strings and sounding board.
• For all instruments, like anything else, the dispersion pattern depends upon frequency and size of the instrument.

The pattern that is reproduced is dependent upon the mic setup whilst recording. Mixdown and mastering will generally determine the sound stage. I agree with the rest that there is probably little the speakers can do to change that. A live room will provide more sense of space but that is the room, not the recording. A dead room will more accurately reproduce the recording but most people prefer a room with some reflections. And of course it is in general impossible to say exactly what the environment used for final mastering was so you have no real reference. You might know the recording venue of a live event, but mic placement and mastering sets the final ambience, not necessarily the hall.

Binaural, anyone?

IMO - Don

 

[GaryProtein]

. . . . What is the radiation pattern of the human voice?. . . .

Paul Klipsch sees Amar Bose on the other side of the road, cups his hands around his mouth & yells- "Hey Amar, is everything ok with you?"

Amar Bose, cups his hands facing backwards & puts them on the sides of his cheeks & reply's, "everything is just fine, thank you!"


Sorry about that. Now back to our regularly serious program. . . .

 

[amirm]

The question has infinite answer anyway. Here is the radiation pattern of different makes of classical guitar: http://acoustics.org/pressroom/httpdocs/156th/bader.html

 

[GaryProtein]

It depends upon the instrument. I don't have studies off-hand, but off-the-cuff:

• Brass instruments radiate out the bell, with dispersion dictated by bell taper. Note French horns' bells point "backwards" so you get reflected sound.
• Strings radiate from sounding holes (if any) and directly from the strings as they are plucked/bowed/strummed/whatever.
• Most reeds radiate from the opening of the instrument, e.g. "bell" end of a clarinet. Some radiate from the top (bassoon), some from the bottom (clarinet, oboe), and there is some direct radiation from the reed though it is usually small.
• Flutes radiate from the embouchure hole on the lip plate and out the end of the tube. (Solo flutes often use two mics to capture both.)
• Piano radiates from the strings and sounding board.
• For all instruments, like anything else, the dispersion pattern depends upon frequency and size of the instrument.

The pattern that is reproduced is dependent upon the mic setup whilst recording. Mixdown and mastering will generally determine the sound stage. I agree with the rest that there is probably little the speakers can do to change that. A live room will provide more sense of space but that is the room, not the recording. A dead room will more accurately reproduce the recording but most people prefer a room with some reflections. And of course it is in general impossible to say exactly what the environment used for final mastering was so you have no real reference. You might know the recording venue of a live event, but mic placement and mastering sets the final ambience, not necessarily the hall.

Binaural, anyone?

IMO - Don

Thanks for the interesting post.

On the flutes, is there a certain distance from the embouchure and the end of the tube that the microphones are best positioned?

In the recording, are the two mics mixed with a certain volume ratio between the two? When listening to the live flute, the closer you are to it, the more "breathy" it sounds compared to a greater distance.

 

[amirm]

What is the radiation pattern of the human voice?

Turns out this has a reasonable and simple answer. The directivity of a human voice is just a bit wider than typical speaker! For this reason, you can have someone talk at the different positions you think of putting a speaker and have them talk and see what you think of it. This also allows a lot of research to be done on human voice as a proxy for a loudspeaker.

 

[DaveyF]

It depends upon the instrument. I don't have studies off-hand, but off-the-cuff:

• Brass instruments radiate out the bell, with dispersion dictated by bell taper. Note French horns' bells point "backwards" so you get reflected sound.
• Strings radiate from sounding holes (if any) and directly from the strings as they are plucked/bowed/strummed/whatever.
• Most reeds radiate from the opening of the instrument, e.g. "bell" end of a clarinet. Some radiate from the top (bassoon), some from the bottom (clarinet, oboe), and there is some direct radiation from the reed though it is usually small.
• Flutes radiate from the embouchure hole on the lip plate and out the end of the tube. (Solo flutes often use two mics to capture both.)
• Piano radiates from the strings and sounding board.
• For all instruments, like anything else, the dispersion pattern depends upon frequency and size of the instrument.

The pattern that is reproduced is dependent upon the mic setup whilst recording. Mixdown and mastering will generally determine the sound stage. I agree with the rest that there is probably little the speakers can do to change that. A live room will provide more sense of space but that is the room, not the recording. A dead room will more accurately reproduce the recording but most people prefer a room with some reflections. And of course it is in general impossible to say exactly what the environment used for final mastering was so you have no real reference. You might know the recording venue of a live event, but mic placement and mastering sets the final ambience, not necessarily the hall.

Binaural, anyone?

IMO - Don

+1

Since the vast number of recordings are initiated in the studio environment, the ability of the mike to pick up the 'overall' sound is what the engineer ultimately has to work with.
Therefore, I do not think the a'phile has to concern him/her self too much with this issue, as the recording engineer has already captured everything that they ( the listener(s)) are going to hear on a particular recording.
OTOH, IF one plays an instrument, when playing in front of a 'live' audience, this can come into play a little bit in regards to the ambience and reverb that we want to have the audience experience.

 

[NorthStar]

That's a cool thread; the capture of the musical instruments from their radiated sound pattern by the microphone's own directivity and positioning...the recording techniques.

The loudspeakers have their own radiation pattern; from their drivers and designs. But it starts @ the music recordings themselves, like Kal mentioned that point earlier.

Some musical instruments have wider, more spacious radiations, like an organ for example or a piano, as compared to a cello, a violin.
...And where the mic(s) is/are positioned to best capture the tonality and natural dispersion of each musical instrument.
...My own thinking without googling around.

I recorded my own playing (guitars, flutes, harps) and using one, two and three mics, and experimenting with different positioning, and also restricted in my choice of mics, mainly dynamic omni/cardioid (polar pattern), and directional condenser mics. There is a balance of science (techniques and acoustics) and magic in the art of music recordings.
I just talked to my friend pro musician, and we talked briefly about this very subject. ...That Larry King's mic type for vocals, and other mics for various musical instruments.

Excellent subject.

 

[DonH50]

Thanks for the interesting post.

On the flutes, is there a certain distance from the embouchure and the end of the tube that the microphones are best positioned?

In the recording, are the two mics mixed with a certain volume ratio between the two? When listening to the live flute, the closer you are to it, the more "breathy" it sounds compared to a greater distance.

I am not a recording engineer, though have dealt with this on and off over the years. I am sure others are far more qualified to answer. That said, I don't have a good answer because it depends not only on the flute but also the player. Some flutists like to move around so you have to keep the mics back; others are pretty fixed. As you say, too close to the embouchure hole and you pick up a lot of breath noise (some like hearing that in a recording, some don't). And there is how much pickup of other sounds is impacting placement, mic pattern, etc. I like large diaphragms for their lower noise and higher sensitivity but I have seen small condensers and most everything in between used. I typically hang one upside down around the top of the music stand to pick up the embouchure hole and a second on a stand to the right maybe a foot away to pick up the sound from the foot. I have fairly often used a medium condenser end-fired mic like the AKG C1000 for the embouchure hole, sometimes with the hypercardioid filter installed.

I try to get roughly equal sound from each mic since different frequencies peak at one or the other or both places. It is tricky since mics are usually placed at different distances and are sometimes different mics. You also have to be careful to not introduce sneaky comb filter etc. effects from the two mics in the mix.

I am very much an amateur with respect to recording; been way too many years and I just do it now and then for fun or a little spending money when asked. Hopefully as pro will jump in and gave you a better answer. And hopefully I am not completely off-base! - Don

 

[DaveC]

I don't agree the speaker should radiate the same as the instrument unless a totally new playback system is under consideration... having speakers and recordings whose only purpose is to recreate an instrument would be interesting but complicated and expensive.

For stereo the way it's currently recorded I think a speaker and acoustic environment where the listener experiences mostly direct sound is the most accurate as it contain the spatial information in the recording, which takes instruments radiation patterns into account, unmolested by too many room reflections. This allows the soundstage to take on the dimensions of the recording space rather than the listening room and fine detail and reverb attributed to the unique radiation pattern of instruments is preserved best this way.