The Spectralyzer

The Spectralyzer App is a novel, colourful and informative way of "seeing" the frequencies present in sounds. 


The Spectralyzer displays sound as a continuously changing, 3-Dimensional, rainbow coloured visual landscape, created from the frequency content of the sound picked up by the microphone.

Purchase the Spectralyzer iPhone/iPad/iPod Touch App





The Spectalyzer is a piece of interactive art, constantly changing according to the acoustic environment.



The Spectralyzer, created by musician / producer / audio / software  / systems engineer Martin P Simpson, was born whilst listening to Music, dancing and thinking about Life, the Universe, Fourier Analysis and Sinusoidal Additive Synthesis. 


He imagined the music he was litening to as a surface of sine waves of different wavelength tavelling towards him, the different frequencies spread out like the keys on a piano. 


He soon realised that viewing sounds in this way would have made a powerful tool during his career as an Audio Engineer.


And so began a quest to develop that idea into a piece of software in order to better understand Sound, Music, and many more things beside.


As you learn to understand sound by using the Spectralyzer, so your ability to interpret sounds may move towards that of those legendary Engineers who's ability to understand Audio gives them the label "Golden Ears".


The underlying maths in the design of the Spectralyzer does not use the Engineers standard tool, the Short Term Fast Fourier Transform (STFFT).


Instead, Martin returned to the maths that, during the final year of his Electronics degree many years ago, moved him away from Electronics and opened him up to the world of Digital Signal Processing and using computers for audio.


As a result, the Spectralyzer uses carefully designed digital models of analogue resonant filters.


This resonant filter based approach seems to be a better model of resonant nature of our cochlea than the STFFT.


In its current version the Spectralyzer has 12 filters per octave, one per well tempered semitone, referenced to A440. 


A440 is highlighted for an easy reference frequency familiar to musicians. 


Each semitone is represented by a different colour of the rainbow. The rainbow repeats each time the frequency doubles, or every octave.


A piano keyboard at the front acts as further frequency indication. White lines at the front and back of the surface allow you to see 2-D frequency content shapes.


The 3-D surface can be viewed from different angles by tilting the device. It can also be moved and zoomed using touch/pinch gestures. 


The direction can be changed using the direction button to toggle the direction from towards you to away from you.


The 3-D surface generation can be paused using the pause/play button for a more detailed examination of a particular sound.


When running from the device microphone, the Spectralyzer allows a detailed estimate of the frequency content of the surrounding ambient audio environment, limited only by the frequency response of the device's microphone.


With the addition of the Apple Camera Connection kit, digital audio USB devices can be connected to the iPad. This turns the Spectralyzer running on the iPad into a more serious audio analysis tool, removing the limitations of the in built microphone frequency response by feeding it with digital data. 


As well as being an educational tool that should help reveal what Pythagoras was talking about, the Spectralyzer has significant uses for audio engineers, sound designers and musicians.


We hope the Spectralyzer is of use to you and welcome feedback.



Buy the Spectralyzer iOS App