First Experiments

Blumlein, M-S, ORTF, NOS, XY
not shown- Spaced Pair & Binaural

Spent 4 hours today in the university SSL studio beginning my initial experiments into the different stereo recording methods. I was met with a number of set backs including dilapidated stands which couldn't hold a microphone straight above the base, let alone at the extent of the boom making it very difficult to position the microphones close together without them drooping onto each other. Once they were finally cabled up we'd discover that half of the cables were faulty, the re-wiring requiring the mental agility usually associated with solving chinese puzzles to complete.

Finally signal was flowing all the way through to the AWS, but there it stopped, for some reason that neither I, nor Eddie could understand. Eventually we decided to bypass Pro-Tools and record in Logic instead.

By this point it was getting late in the day and patience was wearing thin, the realisation that these experiments would probably had to be repeated had sunk in however I was determined to get some useable results that at least proved the validity of the different methods. With the help of my friends Mike and Holly, I recorded samples of moving sound sources as well as simultaneous sources to demonstrate the improved intelligibility offered by stereo. 

Listening back to the results confirms a few of the basic assumptions made by the research however it also demonstrated how the originally designed experiments were flawed, with the microphones shadowing each other and interfering with the stereo image. The next set of experiments will be conducted using the acoustic testing device CLIO and only one of the techniques setup at once to control the variables although the recording environment will inevitably compromise the results somewhat.

Progress Report

It's been a while since I've last posted, which isn't to say I haven't been doing work, I just had a lot of other deadlines just before Christmas pushing my dissertation onto the back burner. Now that 2011 is here I've spent the last week putting together my progress report detailing to my tutor exactly what progress I have made, where I'm behind and how my time plan is being adjusted to make up the difference.

Most of the research into microphone techniques is now complete, so I can now move onto researching some methods of reproducing stereo images- over headphones, speaker systems etc. and the processing that goes on to create a coherent image. I will also be investigating the artificial creation of stereo recordings through pan pots, delays and assorted plugins.

This Thursday afternoon will be the first of my experiments into the researched techniques. I will be setting up several techniques simultaneously and then recording sound sources at various points throughout the field, varying the angles of the microphones and the distance from them to gauge the effect this has on the image.
The microphones and techniques I will be investigating are:

Technique	Polar Pattern(s)	Microphones
Co-incident Pair: Blumlien	Figure of 8	AKG C414 x2
Co-incident Pair: XY 90° hypercardioid	Hypercardioid	AKG C1000s x2
Co-incident Pair: XY 180° cardioid	Cardioid	AKG C451 x2
Co-incident Pair: Mid-Side	Figure of 8 Cardioid	AKG C414 Neumann TLM103
Near co-incident Pair: ORTF	Cardioid	AKG C414 x2
Near co-incient Pair: NOS	Cardioid	Matched pair Rode NT1A
Spaced Pair	Omni-directional	Audix TR40 x2
Binaural		Soundman in ear mics
Surround Sound		Holophone H3-D

I will post some pictures and perhaps a few samples soon.

Continuing Research

Not as much progress as I'd have liked due to impending deadlines from other modules and a massive amount of time currently being spent in the studio.

However I have managed to obtain a few more resources through the library which will help with my research into the microphone techniques and how humans localise sound. A Journal article from the AES which is available online and a copy of Spatial Hearing by Blauert.

The good news is that I have completed my placement module today which mean that next semester I will have only a single module and my dissertation to work on, So I will have plenty of time to do the experiments, research, final recording and analysis.

Research- Microphone Basics

This week, continuing from looking at how humans localise sound, I have been introducing the basics of microphones looking at the moving coil vs capacitor microphones, polar patterns, sensitivity etc and how the right microphone selection is needed for creating a Stereo array.

Research- How Humans localise sound

Have been researching into the history of stereo a lot more thoroughly since handing in my project proposal. Been reading some very interesting books including Stereo Microphone Techniques & Spatial Audio which will come in handy. I also listened to a BBC Archive Hour program on Blumlein, the man who effectively invented stereo recording in the 1930s and it was fascinating, the man was literally a genius.

Today has involved me writing up my notes into the first section of the research looking at how humans localise sound. Basically it is the combined result of the different levels at each ear and the time delay between sound reaching each ear, obviously a little bit more complicated than that but it gives you the gist of it.

Had a meeting with my supervisor today as well which went well, just making sure that the direction of my research is correct and ensuring that I reference things correctly and often.

Welcome to my dissertation blog...

On the advice of my project tutor to keep a log of the progress I'm making on my project I have decided to keep a blog, this blog. I don't expect this to be of much interest to the rest of the world but you never know- If at the end anyone would like to see my dissertation I'll see about posting it perhaps.

Anyway, my dissertation is titled- 'An investigation into Stereo Microphone Techniques and their Applications' which is pretty self explanatory. During my placement at Modern World Studios different stereo techniques were often used especially for recording drums and strings. One day we setup 9 different stereo techniques at the same time to see how they each recorded the stereo field- this was really interesting but I didn't get enough time to follow it up with any real investigation, hence my dissertation and final year project.