radioplay: hw5

localization cues, Schroeder-style reverb, pitch shift and / or resynthesis

The assignment is to create a short radioplay with a recorded text, stereo audio effects and sound effects. Shoot for a duration of around 120 secs (plus or minus 30). This is a demo to introduce several techniques which will be described below. Though it won't be strictly-speaking a binaural recording, it is intended for headphones. Techniques include localization with interaural intensity difference (IID), interaural time difference (ITD), Schroeder-style reverb, and processing for time warping and pitch transposition.

True binaural recording uses stereo mics listening outwards from inside your ears to capture as closely as possible the exact waves your ear canals receive. Played back over the right headphones, it preserves the IID and ITD cues that are basic to sound localization. We'll fake those using a chuck patch pwrAndDelPan and its OSC-enabled cousin, pwrAndDelPanOSC. But at this stage we limit our synthesis model there, in terms of true accuracy. The real binaural technique captures filter (transfer function) differences caused by body parts shadowing and reflecting sounds from various directions: the ear flaps (pinnae), head, shoulders, etc.

Early work in binaural recording was accompanied by predictions that its superior imaging would attract a huge following and everyone would eventually listen through headphones. A few decades later, this has yet to happen, at least in the sense of offering a large selection of binaurally-mastered works. Such works are still problematic for loudspeaker reproduction and that's one thing that's holding back wider use. And besides, would anyone want to go about their lives listening with headphones... definitely a new moment now, but for reasons not related to the fantastic imaging capabilities of binaural techniques. The ubiquitous earbud phenomenon is begging for binaural content. For a position paper on where this may be going see Jens Blauert's AES Heyser Lecture. He makes a provocative case for binaural as a part of an increasingly realistic synthetic world combined with many other contributing modalities.

One artist whose work leverages the medium is Janet Cardiff. Her work already combines various modalities and binaural is one of the key ones. She composes site-specific 3D audio narratives with spine-tingling interplay of real and phantom presences, binaurally produced. Her telephonecall from SFMOMA 2001 is a benchmark piece that opens up the possibilities of what you might expect to compose for pod-like devices. The composition led participants by the nose through the gallery, each holding a camcorder in playback mode with a pre-recorded self-guided tour. You'd turn a corner and someone in your earphones would be there singing in the space (acoustically convincing, so that you could point to them) only they weren't there then, but at some other point in time, past, alternative present, or future.

The 220a homework factory isn't directed to pod players and walking around, yet (but that's a good idea for the future, or perhaps a final project this year's 220c class). Instead, your radioplay assignment will be suited to the tethered headphone setup at the CCRMA workstations. Start by picking a short text which might be a monologue, group dialog, or whatever you want, even a comic strip (but it should have a script, and you can write it if you'd like). You'll use your own voice and possibly other voices in combination depending on the text to be read. If indeed it's a dialog, invite others to read or if you're theatrically inclined, use your voice for the different characters. First, second or third person narratives are all fine and I'm hoping we'll get a variety from the class.

Hint #1: timing in the dialog track of a radioplay is different than straight reading and you'll need to leave gaps which will provide space for sound effects where appropriate. Pace your reading accordingly.

Hint #2: this assignment involves lots of intermediate files, so invent a descriptive naming scheme and stay consistent.

source material

localization & reverb

sound effects, time-warping, transposition