acoustics & signal processing

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Perceptual binding of harmonics - and pop out

This is a little demo that we found described in the book "Vergleichende Tierphysiologie" by Neuweiler. It nicely illustrates that multiple harmonic components in a tone complex are usually "perceptually bound" and not individually perceived (unless you force them to "pop out"). The sounds in this demo are two simple "tone complexes". The first tone complex, let us call it tone A, comprises the first ten harmonics of 200 Hz (i.e. 200, 400, 600, ... , 2000 Hz and so on).

Modes of Vibration Caught on Camera

In the previous animation you have seen how a plucked guitar string will vibrate at numerous "modes of vibrarion" at once, and therefore produce sound at many harmonically related frequencies ("overtones"). Just to show that these modes of vibration are real, here a little youtube video by nicogetz, where he placed a camera phone inside his guitar and then played a tune.

Hear it Like Your Grandmother - Simulating Age Related Hearing Loss

As we age, our auditory sensitivity often declines, and the average decline is perhaps a lot more than you might think!


This javascript app calculates a spectrogram from the input to your computer's microphone. (You may have to adjust the sensitivity a bit.) A spectrogram is in some ways similar to the activity pattern that auditory nerve fibers send to your brain, so you can use this spectrogram app to visualize what various sounds or speech would "look like" to your brain. You can pause the spectrogram by clicking on it.

Two Formant Artificial Vowels

A little interactive demo to illustrate the role formants play in vowel sounds.




Lecture handouts and some video recordings of lectures given to the 2nd year biomedical science course in Audiotory Neuroscience.


1) The nature of sound

2) Ear and Brain

Why Missing Fundamental Stimuli are Counterintuitive

The fact that tone complexes with missing fundamentals can be perceived to have a pitch that is below their lowest frequency component can have counterintuitive consequences.

Consider the tone sequence shown in the spectrogram here:



Music to Deaf Ears - podcast

This podcast by science journalist Dr Carinne Piekema explores how hearing loss affects people, in particular how it affects musicians, and what modern prosthetic devices such as hearing aids or cochlear implants can and cannot do for these patients. It contains insightful interviews with inspirational deaf musicians, some of the UKs leading hearing researchers, as well as simulations designed to show to normal listeners what it would be like to have to rely on a hearing aid or a cochlear implant.

You can listen to the podcast here,

converting brain waves into sound & vice-versa



Can this be done?

Is it possible to record the electrical brain pattern of a human in different states (walking, running, angry..etc..) and tranform these into sounds?


What would be the effects of playing this back to the subject?


I am considering this as my dissertation topic for my MSc, any ideas/ knowledge  in this field are highly welcome! 



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