Which has more depth, omni or cardioid?

Brian Farrel wrote:
"HI Rob, I would like to ask you, if you don't mind too much, to help me understand the logic in choosing an omni for upon the set up I'm [planning]. "

For your "Up" mic to be played back on a speaker above the audience in your lecture room surround system, I'd go with the omni because I think the omni mic can produce more depth of the sort this channel might profit from. Here's a a QuickTime movie test I did with the NT2000 parallel boundary rig comparing stereo imaging/localization/depth with the same mics. First are the mics in omni pattern and then in cardioid. The clock ticks pan from left to right in six positions from 9 o'clock, to 10, to 11, to 12, to 1, to 2 and to 3 o'clock.

The localization seems to be stronger with the cardioid polar pattern, but I think the cardioid's tonal balance is more "tuby" (resonant in the low mids) making the ticks with the cardioid polar patterns seem too close. I believe I can also can imagine the distance of the clocks from the mics more accurately with the omni patterns-- for both the closer clock I'm moving and the stationary one in the distance.

Its a subtle difference and harder to hear because the sound bits have a lot of distractions. Rob D.

Studying the Setback Variable of Small Boundary Rigs

Acting on Curt Olson's suggestion, one variable we tested was the distance from the leading edge of our small, head-spaced, parallel boundary rigs to the diaphragm of the Primo EM158 omni-directional capsules. Curt calls this the "setback." We created impulses by striking two large nail "spikes" together in a circle 30 feet away from the mic set-up area. The building was a 100' X 60' wooden barn with a concrete floor. All mic rigs faced the 12 o'clock sound source.

For best results, monitor the following tests with good headphones or near field speaker monitoring.




Here are two QuickTime test movies presenting a progression of four set back distances from three clock positions: 10 o-clock, 12 o-clock and 2 o-clock:

Mic Station 7 Setback Distances: 3" -> 2.5" -> 1.5" -> 1" Large Movie 7mb (48K/16 sound) SMALL Movie 1mb (compressed sound)

Mic Station 14 Setback Distances: 2" -> 1.5" -> 1.0" -> .5" Large Movie 7mb (48K/16 sound) SMALL Movie 1mb (compressed sound)


Next, the same sound samples edited to "toggle" back-and-forth between the maximum and minimum inset distances for both mic stations:

Mic Station 7 Setback Distances: 3" -> 1" Toggle Large Movie 13mb (48K/16 sound) SMALL Movie 2mb (compressed sound)

Mic Station 14 Setback Distances: 2" -> .5" Toggle Large Movie 13mb (48K/16 sound) SMALL Movie 3mb (compressed sound)

To my ears, the nail strikes seem further away at the .5": and 1.0" setback distances compared to the larger distances. This reminded me of omni-directional mic performance in open air, so I added recordings from another rig, this one with front-facing 7" spread omni mics using the same model mic capsules and a single 18" by 18" single cardboard baffle. The sound sources are 30 feet away at 10 0-clock, 12 o-clock and 2 o-clock:

Mic Station 7: 3" Setback -> 1" Setback -> Omni A/B Large Movie 7mb (48K/16 sound) SMALL Movie 1mb (compressed sound)

Mic Station 14: 2" Setback -> .5" Setback -> Omni A/B Large Movie 9mb (48K/16 sound) SMALL Movie 2mb (compressed sound)

Assessments Even with headphones, perceptible differences are subtle at first impression, but with repeated playing, one can detect that the smaller setback distances of .5" and 1.0" seem to create the impression of a larger or more "airy" space.

click on image to view larger

The left-front corner of the wooden barn has a 18' X 18' walled-in area whereas the right side of the barn is open. The sound impulses created on the right side of the room produce louder, longer reverberations. In the above sonogram, one can see the additional volume (blue and red areas) with the .5" setback and the A/B Baffle impulses over the 2" inset in the third and fourth harmonics of the .5" setback and the fourth and fifth harmonics of the A/B rig. The A/B rig has more brightness at the highest harmonics at 12K Hz and 19Khz. I believe the first strike on the left side with the pronounced 3rd harmonic @5800Hz channel was probably due to a performance difference. Another factor that could be adding to the impression of the spaciousness and with the .5" setback is lower volume of and masking from the 1st and 2nd harmonics at 1700Hz and 3400Hz. I

click on image to view larger

The low frequency drones of a nearby factory penetrating the walls makes it hard to evaluate differences in spatial rendering below 1700Hz (which is a very important part of the spectrum to study when considering "spaciousness.") There could be less response in the spectrum between ~400-800 Hz with the .5" setback and A/B rigs (see circled areas above), but variations in the background sounds during the test moments makes this too difficult to judge.

Does the shorter inset have a negative impact on localization within the stereo field? It doesn't seem to. It might even be better:

Mic Stations 14: Quick Sweep of All Clock Positions with 2" and .5" Setbacks Large Movie 5mb (48K/16 sound) SMALL Movie 1mb (compressed sound)


Conclusions There's enough performance difference between the short and long setback distances to merit experimenting with this variable in the field. Its too early to suggest that our Parallel Boundary rigs will generally produce more spaciousness in the stereo image with a small sebacks, but the possibility exists. The similarities in performance between these small setback distances and the A/B baffle rig suggest to me that the small setback distances are allowing the capsules to perform more as they would in the open air-iin this case used with a baffle to lessen high Hz cross-over from the other side with a head-like spacing. These traits are common to both the wooden Parallel Boundary and A/B cardboard baffle rigs. Rob D.

Anthony Lopez: Styro Head Test

As I said in my previous post, I really enjoyed the Styro head with the EM158 omni mics. This rig seemed to be the most accurate in every aspect: localization, depth, and architectural mapping. There are three tests with stryo heads, and of the three, T4-10 is the most successful. For reiteration, here is my edited previous description of the rig in regards to localization, depth, and architecture.

T4-10 Styro Head EM158 Omni Mics.

A) This rig does an excellence job of recreating localization for the human head. When I close my eyes, without looking at the graphic, each clink has a physical presence in my ears and is easily mapped out. Because the capsules are front facing they seem to favor 10-2 o’clock, which makes it harder for me to discern the location of these because the clinks are more immediate and are being amplified by the shape of the head, in much the same way the boundary insets effect the sound on a parallel boundary mic. Here is a comparison of the two rigs for clarification.


Both of these tests display a lot of space and easy localization. However, I think the styro head provides the most.

B) When comparing the depth of the parallel boundary and the styro head, the styro head seems to have a more realistic sense of depth; although, the parallel comes close. Sometimes the depth seems difficult to discern because of the variable amount of force that was used to clink the nails. The clinks sound further away at 8, 3, and 4. And closer at 9, 10, and 11. At 12 the rig seems to have the correct depth. This is perhaps due to the 6” headspace on the foam head allowing the stereo image of the sound to reach both ears properly. At the other positions the opposite capsule becomes a victim of head shadow, something the human head experiences, which causes one ear/capsule to receive more sound sooner than the opposite one.

The main difference between these two rigs is the type of boundary they offer. The parallel has a dense, flat, wooden boundary. The styro has a foam, curved boundary. As has been suggested by Rob D. in class, the curve of the head allows some sound frequencies to roll off easier. As opposed to the square wooden boundary which tends to amplify the frequencies by about 6dB (click to see diagram). One solution, suggested by Curt Olson, is to cut off the edges off the corners of the parallel rig in order to simulate the relative space and shape provided by the human head. The difference in these two mics can be heard in the video comparison. Particularly in terms of amplification. As I explained to Rob, the parallel boundary seems almost like compressed sound. The reverberation seems cut-off and the overall sound seems to have less decay and more presence; compare this to the styro head which seems to allow more decay and reverberation to be present; perhaps due to the differences in the shape of the boundaries.



However, one problem with this rig is that the human ears are actually side facing, with the ear cartilage acting as a sound collector, while the capsules are front facing. It would have been interesting to create a test with some kind of ear-apparatus attached to it like an ear.


C) This rig does an excellent job of mapping out the architecture of the space. When I listen to this I can pretty much visualize where every wall was. I know that 8 sounds much further away because there is a lot of dead space behind that area, with a wall much further from the “clinker” than any other position. From 9-12 there is a wall directly behind the clinker, 9 sounds like it is further from this wall though, and 11 sounds very sharp, like the clinker was standing in corner with all the sound being collected and focused before being bounced back. This person was also standing near the car which could have being reflecting a lot of sound. 12 o’clock sounds perfect. The capsules are facing forward and the clinker is in front of a large wall, so the sound is thrown right back. 1-4 positions mimic the 8-11, but with less volume, perhaps because the clinkers used less force, or because there was more space, particularly at 3 where there was a huge depression in the room where the loading dock was, this clink seems to travel for a while, perhaps the longest on this rig.

I have created a comparison video containing the clinks from clock positions 2-4 in order to compare the depth differences in the position, which I think has the most noticeable depth. This video contains comparisons of the 2-4 clock positions from the following tests: T5-Dead Center (styro head), T4-10 (styro head), T4-2 (styro head), and T5-3 (parallel boundary). The point of this test is to draw comparisons of the same rig at 3 different positions, and to give a comparison to the parallel boundary.

Test Link

In this video, the styro head tests have an obvious spaciousness at the 3 o’ clock position. As I explained earlier, this is where the depression in the room where the loading dock is. Because there is more space for the sound to reverberate in, the clink sounds more distant than the rest of the clinks. Compare this to the 3 o’clock position of the parallel boundary in which the sound loses this quality because of the amplification of the boundary on parallel.

All of the styro tests sounded pretty close, however, I still think T4-10 was the most successful. I get the best sense of depth, localization, and architecture from this rig. I think that any immediate differences in the quality of the styro head rigs was perhaps due to the variations in force used by the clinkers.

Josh Dirks: The warmth of a cold warehouse

The "Anti-Wedge" Stereo Boundary Mic RigI constructed a mic rig for the Barn Tests which was a boundary capable of variance in width of boundaries (therefore width between capsules), and in the angle of the boundary, it's capable of functioning as a SASS as well as a parallel boundary (blocky) rig. The rig that I constructed was designed to give better separation of the channels and therefore, ideally, a better spatial imaging of the environment. In the tests that we did at the barn many things shown out. Sometimes the acoustic "picture" was nicer than other mics, sometimes not. This had a bit to do with the separation between capsules that I was using. As I widened the spacing I would loose a little in the room image while gaining softness and clarity in the middle strikes. This is what I have chosen to focus on: the warmth that is acheived through my mic design on the 11, 12, and 1 o'clock strikes.

In the first test on my rig the boundary panels were set in a way similar to the standard blocky rig except that rather than being parallel, the front of the panels are turned out from the center 10-12 degrees, this was a constant for all further tests. This is a method Curt Olson found beneficial when attempting to get good separation of channels and a clear audio image, though he was, I believe, recording outdoors. The EM158 capsules were front facing, contrary to what the quicktime graphic says, and inset 2.5 inches, this also on Curt's recommendation as being approximately the best distance for this style of rig, therefore this was also consistent throughout my tests. The sole difference in all of these tests was the separtion of the mic capsules.

TEST #6

test6-4
In test 6-4 I set the EM158 capsules a 7" separation. I decided to pair this test with Rob's Rode NT2000 test. Not only is it the same separation and inset as my mic, it was conducted during the same test. By listening to test6-4 and test6-16 back to back you can hear a slight volume drop in the Rodes. This can be due somewhat to the mics being placed further back in the room, though it was only a few feet. Oddly the gain would seem to be higher in the Rodes seeing as they are unobstructed from the line of sound coming from the center striking areas. The anti-wedge delivers a clear sound, yet keeps from over modulating on the hard 11 o'clock strike right next the wall. The sound remains clear, and though the volume sinks a little as the room opens up at the 1 o'clock, we can still clearly hear frequencies across the spectrum, as well as hearing a nice drawn out decay, allowing us to interpret that the room has opened up in this area. The rode however seems to lose volume and decay on this strike leading us to a poorer image of the room, the anti-wedge even picked up a slight echo from the corner. You can see by the sonograms that the gain is much lower on the Rode test, obviously, but also that the breath of the signal is not as complete as that of the anti-wedge. Given more volume and a more open environment the rode may have performed better, it does seem to have very low noise, but for this test at this volume the anti-wedge gave a clearer sound and better room image.
test6-16

~2mb QuickTime movie comparing the two rigs back to back

TEST #7








test 7-4
In this comparison we can see one of the great advantages to this type of rig in this environment. I lined up the antiwedge against a 2 boundary PZM rig with the same EM158 capsules and same distance between them, it would have been 3 boundary if it was placed on the floor or the bottom boundary had been larger, but for this comparison we will call it a 2 boundary. It is a excellent sound catcher even without the third boundary and has a much higher gain than the anti-wedge. We can hear in the 11 o'clock strike that the gain spikes and distorts the sound. If used in another setting this accuity could be useful, but it only hurts here. We can still localize the sound from side to side in this test, but the difference between 11 and 1 is hard to measure because of the distortion. The anti-wedge in this test performed rather well, in my opinion slightly better than the test prior. The separation was only increased 2 inches, to 9 inches, for this test, but the richness of the sound improves notably. The imaging is better via increased separation of channels and stronger decay. Again we can look at the sonograms and see how the sound has changed. The gain has slightly dropped between test 6-4 and 7-4, but what has occurred in its place is the register of even more frequencies in the spectrum and even less of a jarring treble. This rounds out the sound and makes it very clean and very distinguishable.
test7-13

~2mb QuickTime movie comparing the two rigs back to back

Test #8







test8-4
In this comparison I'm not using sound bytes from the same test. I chose to use a test in which the same separation is used, 11 inches, to try to discover the benefits of the boundaries. I am using the a dowel test, front facing like the antiwedge, to compare depth and localization. The lack of boundaries in the 6-8 test seems to give it a far away and airy kind of feel. We don't get the clear image that the anti-wedge gives us. We can tell in the dowel test that the room does open up by comparing the gain between the 11 and 1 o'clock strikes, but without the separation of boundaries or a baffel the distiction is muddied and we can't place the sound precisely. The antiwedge does allow us an better image of the room than the dowel, but unfortunately the gain has decreased from the previous test and the warmth of the sound is not quite as rich.
test6-8

~2mb QuickTime movie comparing the two rigs back to back

TEST #9








test9-4
This comparison is again between two samples from the same test, the anti-wedge with a 17 inch separation and a dowel rig with an 18 inch separation of capsules set at ORTF. This is a somewhat drastic jump from the previous width, and it can be heard. The gain again drops dramatically in the antiwedge, but it still maintains its clear separation and "soft middle". The gain however is still higher than the ORTF rig, which doesn't have anything obstructing it from the sound. This may be one of the most telling features of the anti-wedge, its ability to pick up sound while automatically separating channels and tapering the overly harsh spikes. This separation seems to be a little excessive for this kind of testing, the 11 or 13 inch were very clear and discernable. But it could be useful for increased separation of channels in the outdoors or a crowd/event setting.
test9-8

~2mb QuickTime movie comparing the two rigs back to back

All in all the antiwedge performed very well in all its tests that I put it through. For the amount of money put into it, not to mention the capsules, it seems to be a strong performing affordable mic rig that can be contoured to fit many circumstances.

Nails in Stereo: Brennan's Picks

Test 03, Station 07















Much like my other choices, this station exhibits very clear spatial differentiation. Only the pairs of 9 and 8 o'clock and 3 and 4 o'clock get slightly muddled together spatially, and this can probably be attributed to the station's forward-of-center positioning. This position can also be inferred through the dinstinctive percieved distance between 8 and 12 and 4 o'clock positions - the hit on 12 is clearly much closer to the listener. A somwhat distinct architectural impression can also be detected by comparing the longer echoes of the 9 and 3 o'clock dings (longer distance to the wall) to the more succinct reverberations at 11 (the portruding corner with the jaguar) and 12 (the very close front wall) o'clock.

Test 04, Station 10















I'm surprised I would pick something as gimmicky as a styrofoam head rig, but it probably had the most consistent and noticeable localization of any of the tests. Every single hit sounds like it's right where it should be in both depth and orientation. The station's left-of-center location can also be percieved by comparing the louder, more insistent left-hand and forward hits to the somewhat muted right-hand hits. Once again, the echo lengths tells a story of the room's shape - longer at the left and right and shallower at the front and front-left.

Test 09, Station 13















This PZM rig distinguishes it self from the other two (unsurprisingly) with its gain boost, particularly in the mid to high frequencies, that serves to give this recording a more airy feel with what seems like more distinct echoes. This higher gain is most likely the cause of the wince-inducing overload at 11 o'clock. However, this rig also exhibits great localization and somewhat consistent depth, although it does indicate a relative bias towards the 10 to 2 range - these hits seem closer even though they shouldn't be. Still, this rig seems to have a subtle element of space that makes the listener percieve themselves being in a large room. Maybe it's the airy, mid freqency boost from the PZMs.

Treble Centricty & Stereo Field Localization

Curt Olson asked me to compare the omni-directal and cardioid positions on the multi-pattern NT2000 mics in the parallel boundary rig pictured here. I've quickly made a 3 minute mp3 test recording of clock positions in an arch ~2 feet around the front of the rig. These are not perfectly positioned stations!

It seems to me that treble centricity is one of the key factors we are trying to accommodate with these rigs and capsule orientations.

When the capsules are facing forward and there's a barrier creating 1/2 omni patterns on both sides, the tonal gradation goes from 0 to 90 (from front-center to hard left/right) with 0 being the brightest and 90 degrees being the darkest. (Of course, the field extends further behind and get progressingly darker due both to the polar pattern and the ears providing more baffling as well.) The same 0-90 spread should occur with the cardioid pattern except with more tonal contrast going from 0-90.

The creation of a uniform spectrum across the front of the stereo is different from human hearing. Some prefer the Pseudo Sass's "3/4" positions in which articulated left and right "centers" are created, but this also differs slightly from human hearing because sounds coming in directly from hard left and hard right are the brightest to our ears. So, If I prefer the stereo field to have an illusion of a spectrally symmetrical "vista" across the front with no darker middle, I should like somehing about using the cardioid pattern,.. but someone else go first! Feel free to chop up the mp3 so its easier to compare. Rob D.

Anna Krutzik's three favorites

T4-07
This recording has a really nice full ring on the echo of the nails. It fills up the entire space, giving it lots of dimension. It makes it easy to hear/imagine how far away the nails are. There is also a decent amount of localization between the different dings.

T9-02
What I like about this recording is that you really get a good sense of the entire building. You can hear traffic in the background and other noises giving it the sense that it's in an urban setting. I don't really listen to the dings so much as the other sounds that are captured on this recording.

T6-04
This recording has very good localization throughout, but it's especially seperated between 1 through 4 probably because its location at test station number 4 makes it closer to that side of the "clock."

Anthony Capener - Baffle Variable vs. Capsule Variable

Baffle Variable vs. Capsule Variable
EM-158- w/ Baffle
OMNI ORTF- w/ Baffle
OMNI ORTF- no Baffle
Cardioid ORTF- no Baffle

The Primo EM-158 high sensitivity condenser microphones used at station two with a baffle provides Stereo space. Test nine station two was recored with Omni (no baffle). Capsule Variable- I appreciated the recording's spatial image less after comparing it to other ORTF test. Similar to the Omni capsules, the Cardioid capsules called attention to the the ten and two positions. There's a significant difference between the two positions for the Cardioids ability to capture the stereo space. There were intruding walls of a side room at the 10 o'clock position and the capsules captured a clear timing difference to the 2 o'clock position where the space of the room was open without the intruding dimension. The use of a baffle called less attention to this and made for a better overall stereo image. This test demonstrates the benefit of using a baffle as the main variable verses a change cardioid and OMNI capsules as being the only variable.
-Anthony Capener

Anthony Capener EM-158 vs. Sound Pro Lavaliere

EM-158 vs. Sound Pro Lavaliere

Test number one, station two (T1-2) was one of the recordings that attracted me the most (for test one), mainly because I compared it to station number five's Sound Pro Lavaliere microphones. The Primo EM-158 high sensitivity condenser microphones used at station two sounds more exact or more realistic than the Sound Pro Lavs. The recording has a more metallic feel and that characteristic of the nails is continued throughout the decay. -Anthony Capener

2 o'clock position strikes only

Left: Primo EM158 Capsules; Spread 13"; front-facing with Baffle

Right: Panasonic WM-61A's Capsules; Spread 13"; front-facing without Baffle

Mining the Pieper Barn Audio Test Files (Jose Montoto)

Read it here...

Noise Floor? What Noise Floor?

For my performance review I thought it would be interesting to compare the self-noise of the electret capsules. I had noticed that the SoundProject Omni's had a slight buzz when I listened closely, so I wondered if there was any such subtle signature sound for each of the capsules. As it turned out, given the "test environment" of the Pieper warehouse, I could scarcely tell the recordings apart. But, just for fun and because I thought we needed another pretty picture on this site, I ran off a comparison sonogram of the four capsule mics side-by-side. It was produced from this recording (Test 5) which shares the same left to right order as the picture (Primo, Shure, SoundPro, Rapid).












In the sonogram, the purple-blues are the loudest frequencies and the yellow-whites are the softest. As the image contests, my ears weren't fooling me - in the droning hum of the warehouse, these capsules sounded practically the same. Any subtle differences might be attributed to the different rigs (headphone, parallel boundary) that these mics were mounted in. There are some small distinctions between the mics in the low freqency range (the fat blue bands) that may indicate that the Primo and SoundPro were a little bit quieter, but if one were to really want to test the noise levels of these mics, It might be best to find an anechoic chamber.

Brennan Alcott

added later:
Rob D's linear sonogram at -90dB to 24K:

click on picture to enlarge

Reflected Sound and Variance (Matthew Engel)

T05 Comparative
The measurement of traveling sound towards two different mics from the same sound source is an interesting way to identify and map out the space used in these recordings. The differences in pitch and overall reception of the sound in the two different mics is interesting because it gives a lot of information about how sound is traveling in this space and how it reflects off certain surfaces to reach the mic locations in the center. To lift a diagram, earlier used by Anthony, this is a good reference of the types of ways mics and mic rigs receive and develop certain sound receptions to create what we hear in much of these recordings, however its more important that we pay close attention to the first image because it defines what is being talked about here. It is a graphic depiction of how direct sound and reflected sound reach the mics from the points in the Pieper barn that we were using.
Using information from Test five, I was able to determine a certain amount of variances and sound differences in the way the sound is received by two similar sources in two different positions. These positions do affect the final out come of the sound reception, but it is easy to determine the difference in the decay of the sound in each. The two different sounds from the points 10 and 2, chosen for their placements in cramped and open spaces, create a totally different sound from the one mic setup to the next. This is because of placement of the mics, the mic quality, the space surrounding the sound source, and the recording circumstances such as gain level. But the most interesting aspect to try and decipher from the recordings is the space around the sound source. This space is important because it is the reflected surface of the sound being produced and it is what creates the spatial anomalies and produces the amount of ambiance in the sound itself to let our ears hear that there is resonance and large or small amount of space surrounding the sound source. These two recordings both being done by types of parallel boundary mic rigs, this comparison develops a greater idea of the recording space then by just listening to one individual recording, and this is attributed to the ambient reception difference in each of the two different mics at their different positions.
To get down to it, the variance of space in point 10 is less because it has an almost immediate reflected sound where as point 2 has a more muted and less active sound because it is in the area of the barn with the most space. The tests have been placed here side by side to see for yourself. They are played at 25% slower speeds in the first set, and then normal the second set. The major differences in sound captured in the slowed down versions are very obvious and represent the variances in spatial reflection rather well. Keeping all the other elemental controls and effects in mind, see if you can hear the reflections and differences caused by this very cold space.

Padrick Dunns: localization Test

For localization I selected six different test rigs. They are tested in groups of
two. Starting with:

13'' spread side-facing capsules w/baffle Em 158 and 21'' spread side facing capsule w/baffle

T01-01 and T03-01

I listened to each one about six time while I drew a circle and placed each mark so I could localize each mark. This goes for all of the tests. At first I did it looking at the computer but it took my attention away from where the sound was really coming from. When I closed my eyes I came up with this conclusion. Starting with the T01-01 13'' spread the separation of the sound was much more clear than the 21'' spread this could be because ot the piece of cardboard in the middle. It seemed that the variation is much different from the T010-01 to the T03-01. The sound from T01-01 has separation and you can tell where each sound is coming from where the sound from T03-01 10-12 degrees is way off they sound like their are on top of each other. Where 12-1 their is a large seperation. In conclusion the sound is much more clear when the mics are closer together in this case.

The next two are:

Front-facing w/Baffle 13'' spread em158 and Front-facing w/baffle 21'' spread em158 mics

T01-02 and T03-02

Starting with the T01-02 13'' spread 12-1 sounded right next to each other but 11-12 sounded like there was a large amount of separation. Where in the T03-02 10-11 sounded right next to each other. 12-2 also sounded on top of each other. Each group had its separations but it seems that the closer the mics are together the better the localization of each sound.

The next two are:

13''spread ORTF Em 158 mics baffle and 21'' spread ORTF Em 158 mics baffle

T01-03 and T03-03

The most interesting group was the last only becaule it was different from the first two. As I started with the T01-03 the degree of 10-12 sounded right next to each other as well as the 12-2. It seems that this was the worst test for localization. It was hard to distinguish between the degrees of 10 and 12, also 12 and 2. Then I shifted gears and listened to the T 03-03. The further the spread in teh ORTF baffle the better the separation of the sound. The localizaton was much better and much more clear. In conclusion the further the mic the better the localization in the ORTF.

Conclulion:

If I could pic one mic out of the six for localization it would be the 21'' spread ORTF Em 158 mics baffle. If I could pic a second runner up it would be the 13'' spread side facing capsules w/baffle Em 158. I found it weird that the closer the side facing baffle the better the sound quality and the further apart the ORTF the better the sound quality.

Depth Perception and the wave

Mike Jorgenson

I tried to do a little analysis of the frequencies in the waveforms in relationship to the sense of percieved distance/depth in the recording. First, a few disclaimers. 1) I'm not 100% sure I'm analyzing the frequencies right. 2) The sounds I've chosen are based on what I feel to be good (or poor also) examples of depth. That said, here we go.
I looked at the frequencies using the spectral frequency view in Adobe Audition. I took tests 03-01, 03-14, 08-3, and 10-11 to try to compare a few things. First, I took test 03-01 and 03-14. These clips are from the same test and the particular clicks I compared are the same click. In addition, I chose 03-14 because it's position was not too far off of the 03-01 position. So, in theory they should sound generally the same. However, they are from different rigs. I found a few things. First, I thought in general the 03-01 sounded like there was a little more distance to the clicks. From just hearing it I thought that one of the major differences was the middle and background noise that affected this depth perception. It seems that the brighter the middle and background tones the closer the object is perceived to be. Comparing the two waveforms this seemed to be confirmed. (This sound is the 03-01 rig click 2x, followed by the 03-14 rig click 2x). The 03-14 rig has much more green and orange in this picture, signifying higher energy sound, in the 4k-10k frequency range. In comparison to the other tests I looked at it seems that the tests that sounded closer (08-03 and 10-11) had more frequency response in this same range. The lower frequencies seemed to roll off in the decay whereas in the 03 tests they did not. They seemed to remain consistent from about 6khz down. In the 08 and 10 tests you can visually see this as the green dissipates bulges in the middle (looking vertically at the click) and then sucks in at the lower frequencies. However, there is also something else to it. Looking horizontally across a small range of frequencies (say roughly one 'spike' horizontally) there are different shapes produced by the high energy and low energy colors through the decay. For example, the 03-01 test has a fat, thin base on the left that spikes fairly quickly (see pic). Test 08-03 has a more bulbous base with only a small spike. And test 10-11 has a fairly consistent slope to it. I viewed test 08-03 as having better depth percieved than test 10-11 and worse then 03-01. So it seems that the more gradual the slope of the energy, the closer the sound appears to be.
The rigs that I have chosen to look at actually says something about this I think. Test 03-01 is one of the tests on the dowel with only a simple baffle. Test 08-03 is a double boundary. Test 10-11 is a triple boundary. It seems that the more boundaries you have, the closer the sound is percieved to be at. Like I said though, I'm no expert. But this is what I found to be true.

Stereo vs. Mono. Is it worth it? By Anna Krutzik

For my test of different variables I chose to see if I could hear any difference between the three tests I had chosen as a good representation of stereo when I put them in mono. To my ears, all of the original tests sounded basically the same, with only very minimal variations on each other. While I could hear the stereo effects in the localization of the dings, not much else seemed to really make it "stereo" sounding. And the dings were sort of tempermental, you could tell the direction of some, but not completely all of them.

So, to test my ears, I compared the same tests in both stereo and mono and noticed an immediate difference between the two. In creating a sense of space, the stereo versions win hands down, the mono versions sounding flat in comparison. Of course, hearing the sound surrounding your ears (in stereo) rather than being duplicated into both ears the same (in mono) creates the feeling of actually standing in the room because it mirrors how a person would actually hear, each ear picking up on different sounds based on their positioning and putting them together to create a composite of the space.

As for the localization of the dings in mono vs. stereo, I didn't hear as much of a difference as I would have expected. For whatever reason, I could consistently hear more difference in the location of the dings between 1-4 in the stereo recording. I'm not quite sure if this is my own mind just subconsciously interperating the difference between hearing the dings from the left to the right side as thinking that the right side dings are more localized. Or if there is a specific technical reason for this. So in the mono versions of the tests, I didn't notice that much of a difference in hearing the dings on the left side.

I thought that maybe listening to the recordings in mono but still viewing the animations which illustrate where the ding is coming from in the clock positioning would fool my mind into thinking that I heard it the same as in stereo. And while it did a little bit, there was still an obvious difference when watching the animation and listening to the stereo version.

All in all, I now appreciate much more fully the value of stereo sound recordings and their ability to recreate and place the listener in the space of the original recording.

I recommend listening to the mono versions first and then to their stereo counterparts immediately after to get the full effect that the stereo brings.

Mono Versions
T4-07
T6-04
T9-02

Stereo Versions
T4-07
T6-04
T9-02