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  • 02/08/10 03:55 PM

    Making Sound Effects

    Music and Sound FX

    Myopic Rhino

    Some time ago, I was given the task of making sound effects for a martial art sequence. A short, simple looking fight sequence, that ended up needing a whole lot more sound design than I could have imagined. And so here lies the essence of making sound effects; make more than you think you need.

    Like any project, the first stage should always be research. It is two-fold; how will the sounds be created, and what is my audience expecting to hear. Both are equally important. In addition to the standard categories of foley sound effects, such as footsteps and prop sounds, I found that sound effects for martial arts consist of at least two unique categories. These two unique categories are hits, and movement.

    The Sound of Watermelons

    With reluctance, I pressed the record button, picked up my cricket stump, and slammed the large watermelon that was lying in front of me. "Cracckk!" A most peculiar sound was created, and recorded.

    In my research, I found that quite commonly, smashing watermelons with sticks is the way hit sound effects are created for martial art sequences. That is, the sounds that we have become accustomed to hearing when one character is hitting another. It is the combination of a sharp initial crack and the wet, slushy sound of the watermelon splintering. Not the imagery you would like to be thinking of. It raises a good point however and perhaps the most important point in this article; sound is not what it looks like.

    If a film's production relied entirely on the location sound recorded together with the footage, a film's sound would come across as empty, bland and without any power of suggestion. Take for example, the sound of one person's fist hitting another person's face (and the actors hadn't even done that!) The sound is if anything, extremely low in amplitude and completely without the emotional energy needed to move an audience. Now while an audience is in the most part concerned with the visual element of a film, a film's sound should be unobtrusive and go without notice, whilst having the most profound emotional effect it possibly can.

    While I was having watermelon juice sprayed all over me, I was considering what all this should mean to an audio practitioner. When faced with a piece of film on the screen, how am I going to decide what props to use and record? What microphones and microphone techniques will produce the most emotive sound? That, I have found from experience, can only come from thorough research and experimentation.

    At the time of recording these hit sounds for the martial arts sequence I was working on, I only had my hands on two microphones; a Rode NT3 and a very basic interview microphone I had picked up at a camera store for $40. Obviously the NT3 is a far superior microphone but there were some interesting discoveries when using the $40 interview microphone.

    Both microphones were placed on stands in a fairly dull sounding room around fifteen to twenty centimeters from the watermelon. Pop screens were placed in front of each microphone (in the hope of protecting the microphones from watermelon spray) and fed into a small Yamaha 4-track tape machine. The output of the 4-track was then sent to a computer with a basic sound-card and into the multi-track program Samplitude Studio. First, I recorded for around a minute with only the NT3, giving the watermelon plenty of solid hits, adjusting the input gain on the 4-track with each hit. Then, I followed the same process with the interview microphone.

    When listening to the recordings, I found that the NT3 had far better lower and mid-range frequency response, while strangely the interview microphone had a much sharper higher frequency response. Being a shotgun microphone, the interview microphone most likely had a large peak in the upper mid-range frequencies. The hit sounds had a very fast attack with no decay whatsoever. Satisfied with the recordings, I moved on to recording the movement sounds.

    The Sound of Ferns

    Movement is the second unique sound effect associated with martial art sequences and it was here that experimentation was needed. I thought about how the movement of a martial arts actor needed to be portrayed. They need to elicit the idea of speed, swiftness and power. What I needed was a 'swoosh' sound. I took a walk around the garden and pondered how I could create a 'swoosh' sound. It didn't take long to come across some dead fern branches lying on the ground, and when I moved them quickly through the air, heard the perfect sound I was looking (or listening!) for; 'swoosh!'

    When it came to recording the ferns however, I found the process more difficult than recording the watermelon hits. The level of the sound source was very low, and adding gain to the microphone input added a lot of room noise. I think in this situation, a microphone with a wider polar pattern such as an omni pattern, or even a stereo microphone such as the Rode NT4, would have captured the overall sound better. In the end, I decided to use both microphones simultaneously, spread about twenty centimeters apart and facing about forty-five degrees away from each other. This seemed to capture the fast movement of the fern and give an adequate sound pressure level.

    A Note on Recording Technique

    Recording sound effects follows the same recording techniques as recording music, and while this topic is another article in itself, it should be briefly mentioned here. Most importantly, the limiting of external noise when recording sound effects is essential. Try not to forget, that for every new track you are adding to a film's soundtrack, you are adding noise that could, and mostly will, cloud the final soundtrack.

    Limit the amount of noise by only using as much gain as is necessary to record your sound, try to get your microphone as close as you can to the sound source, and try to only use equipment that operates with very low noise. Where appropriate, try to use noise reduction effects before you present your final audio mix to your editor.

    In the case of this article, ideally I would have benefited greatly by having a more sensitive studio condenser with changeable polar patterns and a good quality preamp and compressor. In that way, I could have found the optimum microphone placement and recording level, without encountering clipping or distortion occurrences.

    The Power of Mixing

    When making sound effects, be it for martial arts sequences, the ambience of a spacecraft, or the complex sound of a war scene, sound effects mixing is an art in itself. Never forget the power of layering, positioning and the use of audio effects. There are a multitude of options when it comes to audio mixing software and there are some amazing open source programs available online. Basically, a program that offers multi-track mixing, some array of audio effects, and the ability to output to various audio formats should be sufficient for most sound effects editors.

    For the project I was working on, I was using Samplitude Studio, which is a very powerful multi-track program that has a long list of features beyond this article. The fern recordings needed to be louder and brighter so I made good use of the program's built in noise reduction plugins, combined with multi-band compression to make the recordings louder, without introducing too much noise or distortion. Not all the watermelon recordings were usable as the first few hits clipped and were very distorted. Some room reverb was added to match the scene of the visuals and soften the samples, slightly distancing the perspective of the sound.

    An incredible amount of subtle variation can be created by simply having different combinations of the same samples, at different levels and panning positions. By using Samplitude Studio's pitch-shifting and time-stretching plugins, I was able to not only improve the movement samples, but I also came away with around thirty new movement samples. I went back to the watermelon samples and used the same technique. This gave me a much larger library of samples, giving more variation to the fight sequence audio. There is nothing worse than having the exact same sample for five strikes in a row. Even if the audience doesn't notice it, someone will.

    The samples created were then carefully synced to the visuals in the video editing program Final Cut Pro. There were more than one-hundred and twenty unique hit and movement samples in total, edited and created from variations of only around twenty original samples. Foley sounds were added later by another sound editor.

    Final Thoughts

    So comes to the end of the article 'Making Sound Effects'. Always remember to experiment with different combinations of sounds and effects, and try to listen to your mixes on other systems to hear how they sound in different environments.

    Never forget the importance of research. It brings understanding about technique and perception, which are two of the most integral factors in creating effective art.

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