The creation of BBB background ambience part 1

As described in my previous Location Recording post, I collected a variety of sounds from Macclesfield Forest, including natural ambience to use as a backdrop for action on screen. There are two environments used for the duration of the film: an idyllic open grassy field, and a wooded forest.

After completing the recording session described in the previous post I decided to revisit the forest with the aim of re-recording the ambience. It wasn’t that my initial recordings were not adequate, they are actually good quality, it was just I felt it would be ideal to collect binaural recordings of the ambience simultaneously with stereo recordings as this would prove extremely useful when it came to subjective testing. Having recordings of exactly the same moments in time in the two different formats would help to make tests as fair as possible.

On my second visit to the forest I again took the Edirol R44 digital recorder as well as two Rode NT2’s, and Soundman in-ear binaural microphones. The NT2s were set up in a coincident (X-Y) configuration for the convenience this offers as well as the convincing stereo imagery which can be achieved. The angle between the capsules (mutual angle) was set at 90°. This is also the configuration of the Rode NT4 stereo microphone which unfortunately was unavailable to book from the university this time around, and so was chosen to allow for coherence should the first recordings be used at the mixing stage.

Challenges

With close to 2 hours worth of soundrecorded I decided to call it a day. Although this may sound like an excessive amount much of the audio will need editing and indeed some will be unusable due to the plethora of irritating unwanted noises one has to contend with when recording ambience, some of which I had never realised would be so disruptive, including:

  • Plane noise – With so many planes flying around, departing or arriving at Manchester airport, you are left with windows of only a few minutes of plane-less ambience.
  • Road noise – Thankfully not really an issue in Macc forest but you still get the odd car or forest warden’s van making an appearance.
  • Farm animal sounds – The sound of cows and sheep, although possibly usable, had to be kept to a minimum as in the film there is no evidence of farm animals.
  • People and dogs – Either in close vicinity or far away, people and their pets proved a problem. The absorption and reflection provided by trees creates an acoustic environment which can allow sound to travel through the forest for some distance. The relative quietness of the area meant that distant voices, footsteps and barking were loud and clear enough to sneak on to recordings from time to time.
  • Flying insects – An incredible nuisance during the summertime. The sound of the odd buzzing insect is not so much of an issue, nor even a few in the distance, but when they get too close to the mic they more often than not ruin recordings in the case of BBB as there is only one shot where a flying insect is visible in the video.
  • Wind noise
  • Bangs and bumps against microphones and stands

Sifting and Sorting in the studio

On listening back to the recordings one thing that stood out was the presence of hiss. The gain on each channel of the R44 was set higher than if close mic’ing and although this increased the overall recording level allowing for more noises to be captured, it also raised the noise floor. On the stereo recordings the the level of desired signal to the level of noise (hiss) was not detrimental to the recording quality. On the binaural recordings however the hiss was more noticeable. Reducing the level of the hiss within Adobe Audition (process explained in more detail here) unfortunately did not reap enough benefit and so the decision was made to not use the binaural recordings at all. Although disappointing I do believe that this will not prove to be a major issue as these recordings are not to be a focal point. Additionally with the binaural panning plug-in I have in mind to use to create the binaural mix I will be able to place the final stereo ambience track anywhere within the soundfield should it be necessary in a particular scene e,g, bird noises coming from above the head of a main character.

Removing the binaural recordings also meant that the first batch of location recordings made with the NT4 were now “back in play”so to speak. Initally effectively discarded as the had now binaural equivalents, these recordings were of good quality and offered slightly different character to the second batch. The main differences were:

  • A more spacious acoustic character
  • Larger amount of activity – more birds, more frequent calls

Because of this I found the first batch of ambient recordings suited the scenes set in the large open field location, where as the more intimate quality of the second batch nicely complimented the relatively “closer” feel of forest.

The next post (part 2) will go into more detail on how the final ambience track was created.

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This entry was posted in Audio, MSc Audio Production, Post Production, Sound Design, Uncategorized, University of Salford and tagged , , , . Bookmark the permalink.

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