Psychoacoustics

Question

Hi All,

I'm working on a new play that really pushes the audience's comfort level. . .

I was wondering if anyone can share psychoacoustic techniques they've found to elicit certain subtle psychological or emotional responses from the audience. I've heard about reversing polarity on speakers to achieve a certain uncomfortable effect. Has anyone experimented with this? I've also heard that sending certain signals through the subs can make the audience feel a bit on edge. Any advice on things to try. Super low frequency sine wave? Square? something else?

Thanks,

Jeremy Bloom Sound Designer

Answer 1

Hey Jeremy,

You might want to check out this post about sound illusions.

http://listverse.com/2008/02/29/top-10-incredible-sound-illusions/

I'm not sure how you would implement any of these in a theatrical setting, but they might give you some inspiration.

Also following on from Mark's post, I read somewhere that the resonant frequency of the eyeball can cause optical hallucinations although I have no idea how true this is (I also read that it was 19Hz but similarly cannot back this up!). I think subsonic is generally a good way to make people feel uneasy but apparently prolonged exposure can cause nausea so I guess you'll have to pick your moments rather subjecting your audience to 2 hours of 1.5Hz (although if you do decide to go with that I'd be interested to hear what happens heh).

Answer 2

I absolutely love psychoacoustics, it is the very reason I fell in love with sound to begin with, but frankly this is a very very hard question to answer. Psychoacoustics are rarely something really tangible like a sound or a certain technique. There are some cases where you can seriously point a finger at it, like the deep sine-wave in Irrèversible, the fading street-amb in Se7en, or, to give a personal reference, a distorted very high frequency tone I just used in a horror movie. But most of these things mustn't bear the entire scene by itself. It's partly because you can never tell how the systems will react to such extreme signals unless you actually do the mixing at the theater, it might be so quiet it makes no difference, but it might as well be so loud people forget the play altogether and just wanna hurt the one responsible. Everything drawing the audience from the action is seriously bad.

Every sound designer has his or her own little tricks and preferences, but mine is very often based in dissonance and insecurity, at least when doing horror, dystopian fiction and action (doing the same thing to a comedy may or may not render it into a tragedy/travesty instead, potentially effing it up completely). It all comes down to context: take a dripping pipe. In a cellar, it will make the owner virtually soil him/herself with anxiety, and give the audience a feeling of discomfort. In the desert, it's the most wonderful thing anyone possibly could imagine, next to a full stream, of course.

All this might very well give you nothing, but I do hope you understand what I meant by this. These things can't be made by the numbers, it HAS to be made by understanding what you wanna accomplish and what makes you tick yourself. Psychoacoustics is exactly what it's named after, based entirely in psychology, but by just listening to your inner voice and trusting your own judgment, you're already halfway there :-)

Answer 3

+1 to @Christian's answer. Just to build on it, it is important to remember that there are two areas of 'psycho-acoustics' in this context; things that will consciously affect the audience, and those effects which subconsciously effect the audience.

Using 'conscious' affects on an audience is all to do with sound-association, where certain sounds draw certain emotional responses from the audience, due to what they associate the sound with, along the lines of Christian's dripping tap example. These usually draw similar reactions from the audience, but not everyone will feel the same. There is a nice little clip on from a BBC show about that kind of thing. I can't find the exact clip but this is a link to that episodes page on the BBC site for a little more info.

I think what you're thinking of though Jeremy are subconscious effects. Using strong subsonics (eg. 4Hz+) or very low sonic-frequencies will most likely put an audience on edge, they'll probably be able to 'feel' the sound more than they can hear it, but again as Christian pointed out this is hard to reproduce practically or well for general distribution and is probably something that's best used when mixed for a specific theatre or setup. And again, use of such techniques, with high or low frequencies etc, has to be carried off well to avoid distracting or annoying the audience!

Is your play just going to be shown in one specific theatre? If so then you'll first need to look at the capability of the equipment you've got. If you've got kit, or can get kit, that's capable of producing subsonic frequencies then try a 16Hz low-level sine, get a couple of people to sit in different areas of the room (edges and centre being most important), and slowly increase the level. You could get those helping to put their hands up when they sense anything different, and maybe ask how it made them feel. You could possibly try similar tests and do a sweep of different low frequencies and judge reactions from that too, to pick an optimum frequency for your theatre. This will take a little trial and error to find what works for your play and your setup but will hopefully come out with some good results!

Answer 4

I'm not sure if this is technically psychoacoustics as it's more about how the body reacts to sound physiologically than our perception of sound. But as we are physical beings, we also resonate when subjected to sound waves of the right frequencies. Much of it is subsonic - below the frequency of human hearing.

1. Head: about 25hz
2. Eyeball: 30-80hz
3. Ribcage: 60hz
4. Abdominal mass: 4-8hz
5. Legs: 2hz(bent knee) - 20hz (rigid posture)
6. Wrist: 50-200hz
7. Lower Arm: 16-30hz
8. Spine 10-12hz
9. Shoulders: 4-5hz

It's certainly true that low frequency sounds at high SPL's at are unpleasant, I've also heard that on more of a psychological level we connect loud subsonic sounds with danger instinctively. As many natural phenomena which are dangerous to us (such as earthquakes) also generate similar sound waves.

Personally, while I think this is definitely something interesting to explore, these techniques are a little over-used - especially in the cinema. Often less is more, so perhaps pick your points carefully. Also, as this is for the theatre, make sure the PA systems where you're playing are up to the task - no point designing a load of subsonic rumbles for a crappy house PA which goes down to 150hz

But also think about the more subtle ways to affect your audience psychologically, as this is often more effective. What are the locations? Are there any sounds around those locations which you can use to create unease?

Answer 5

not directly related to comfort levels, but you can also play with absence of sound. for example- if you play a recording of air conditioning, or similar at a low level for most of the show to establish the noise floor, and suddenly cut it out at some point then the new much quieter noise floor becomes more intense.

Answer 6

I know this an old thread but I wanted to offer a fun trick I found during a production. I had a very tense scene with a building kind of panic with the character, I supported that with this trick. I had a heart beat that was subtly under the mix, just sitting that it was almost inaudible just audible enough that you might miss it, with plenty of bass cranked up on it. Then I slowly started to increase the volume, like Sloooooooooowly, and also slowly increased the speed of the heart beat along with the volume. After opening night my Stage Manager who is also an Audio Engineer and SD told me he thought he was having a panic attack during that scene. That's one I'll save in my back pocket for another production for sure.