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Posted by on May 26, 2016 | 5 comments

Music Cognition and Psychoacoustic Research: An Interview with Dr. Susan Rogers

For this month’s theme of “Research”, Dr. Susan Rogers was kind enough to answer our questions about her work and research in music cognition and psychoacoustics. Susan Rogers holds a doctorate in cognitive psychology from McGill University (2010). Prior to her science career, Susan was a multiplatinum-earning record producer, recording engineer, mixer and audio technician. She is currently an Associate Professor at Berklee College of Music, Boston, teaching music cognition, psychoacoustics, and record production. She is the director of the Berklee Music Perception & Cognition Laboratory where she studies auditory processing in musicians.

Dr. Susan Rogers

Dr. Susan Rogers – credit Jandro Cisneros

 

 

 

 

 

 

 

 

Designing Sound: What drew you towards the subject of psychoacoustics and music cognition?

Dr. Susan Rogers: I have an engineer’s mind. I like understanding mechanisms and processes. I also have a scientist’s mind because I am curious about natural phenomena. Auditory science and brain science attract similar kinds of thinkers — those who are ok with imagining the mechanism and process. We typically don’t view air pressure variations, electrons or nerve spikes in action; we must often infer the process from the resulting behavior or event. Short answer is that it’s just fun.

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Posted by on May 1, 2016 | 0 comments

Sunday Sound Thought 18 – Dependent Perception

As the year continues, many of these posts will be philosophical in nature. Some will be in contradiction to previous postings. These are not intended as truths or assertions, they’re merely thoughts…ideas. Think of this as stream of consciousness over a wide span…

I’ve had this one in the topic queue for a while, but couldn’t quite figure out how to approach it here…until a few days ago.

I walked into a restaurant’s restroom just as someone was leaving. The toilet, which had just been flushed, was refilling. I’m sure most of you can call up in your head the sound of a toilet basin refilling its water supply. This one sounded different. It was far more harmonically complex than the usual peaks you hear in the bed of white/pink noise, and it created this incredible drone in the tiled room. Then the toilet stopped filling, and I realized that the additional complexity was coming from a fan vent in the ceiling. This vent noise, 8 feet above and two feet to the left of the toilet, had sounded like it was coming directly from the toilet…like it was part of that other sound.

The way we perceive sounds in our environment can be greatly dependent on the presence of other sources of stimuli. In this case, both sound were affected by the other. One was enhanced by the presence of another sound, while the other was spatially altered by the first. This phenomenon was entirely dependent on the vagaries of the way our brain processes stimuli. As soon as the toilet stopped, my perception of the vent’s source changed to match its actual location. There are other examples. Michel Chion coined the term “entrainment” for the effect that visual elements in film have in our perception of a sound’s localization.

It’s just another reminder that everything, including sound design, is about context.

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Posted by on Apr 3, 2016 | 5 comments

Sunday Sound Thought 14 – Sound’s Golden Mean?

As the year continues, many of these posts will be philosophical in nature. Some will be in contradiction to previous postings. These are not intended as truths or assertions, they’re merely thoughts…ideas. Think of this as stream of consciousness over a wide span…

This week, I have a question. While I may occasionally ponder the idea, I’ve never devoted a significant portion of brain power to it for a substantial period of time. That might sound lazy on my part, but it’s actually a hard question and I always have higher priority items on my plate.

…and now I’m just creating excuses. ;)

In case you didn’t notice it in the past (or haven’t been visiting the site as long as some other people have), you may have missed the fact that I’m kind of a nerd when it comes to psycoacoustics. Many of the Gestalt principles or “rules of organization” that describe how we perceive visual stimulus have direct corollaries with the way we perceive sound. There’s one that’s difficult to translate though, because there’s such a stark difference in the way we perceive space through our eyes and ears…the Golden Ratio (sometimes referred to as the Golden Mean).

So what say you sound design community? How do you think the Golden Ratio can be related to sound, or can it not?

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Posted by on Dec 23, 2014 | 5 comments

Time And Psychoacoustics

When designing audio we are often thinking of time across a large variety of units: samples, milliseconds, frames, minutes, hours and more. This article is inspired by a conversation I had with Andy Farnell about a year ago at a pub in Edinburgh, right before a sound design symposium, where we discussed about time and the role it plays when it comes to designing audio.

Like most other audio designers out there, I started twiddling the knobs and sliders well before I had an understanding of the underlying DSP. It was eye-opening experience to realise that almost every single DSP effect is related to time. So let’s start looking at a few common DSP tools used in everyday sound design and analyse how time and the precedence effect plays a role, starting from hundreds of milliseconds all the way down to a single sample.

Precedence Effect

The precedence effect is a psychoacoustic effect that sheds light on how we localise and perceive sounds. It has helped us understand how binaural audio works, how we localise sounds in space and also understand reverberation and early reflections. From Wikipedia:

The precedence effect or law of the first wavefront is a binaural psychoacoustic effect. When a sound is followed by another sound separated by a sufficiently short time delay (below the listener’s echo threshold), listeners perceive a single fused auditory image; its  spatial location is dominated by the location of the first-arriving sound (the first wave front). The lagging sound also affects the perceived location. However, its effect is suppressed by the first-arriving sound.

You might be familiar with this effect if you’ve done any sort of music production or mixing. Quite often a sound is hard panned to one of the two stereo speakers and a delayed copy (10-30ms) of the sound is hard panned to the other speaker. Our ears and brain don’t perceive two distinct sounds, but rather an ambient/wide-stereo sound. It is a cool technique for creating a pseudo-stereo effect from a mono audio source.

The first 30 seconds in the video below shows an example of the precedence effect in action. The delayed signal smears the original signal with phasing artefacts after which it seems to split from the original signal and become a distinct sound of its own.

Echos And Reverb

Echos are distinct delays. Reverberation is made up of early reflections which are delayed sounds that arrive first at the listener  (right after the direct sound) followed by a tail that consists of many such delays diffused into a dense cluster. Artificial reverbs are quite often approximated using networks of delays that feedback into each other (convolution reverbs behave a differently).

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Posted by on Dec 15, 2014 | 0 comments

“Hearing Lips and Seeing Voices” – The McGurk Effect

Want to see something that’ll mess with your head?

YouTube Preview Image

Now, you may not have noticed anything all that strange watching the video, but mute the sound and watch it again. After that, close your eyes and listen to just the audio. Notice anything strange now? You’ve just witnessed one of the more interesting perceptual illusions, the McGurk effect.

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