by W.A. Steer  PhD

Audio Spectrum Analyser

This page describes a free audio spectrum analyser which you can download. It uses fast Fourier transform (FFT) to give a real-time ('live') spectrum display on your screen.

Applications

• Understanding audio quality and the effects of digital compression (e.g. MP3) on audio bandwidth
• Detecting problems in audio recording
• Teaching and training
• Speech and audio research
• General scientific applications
• Radio amateurs

Feature and Specifications

• Runs under Microsoft Windows 95, Windows XP, Windows Vista, Windows 7
• Samples an audio stream in 16-bit 44.1kHz mono, then uses a Fast Fourier Transform to yield the spectral analysis in real time.
• User selection of alternative sampling rates, 32kHz, 48kHz
• Supports multiple 'wave input' devices (multiple soundcards, and/or the newer Windows Vista/7 sound model).
• Bargraph peak-level indicator shows time-domain peak levels and onset of clipping distortion (spectrum also goes red).
• Spectrum obtained using 4096-sample FFT with Hanning (raised-cosine) window-function.
• Choice of linear and logarithmic (dB) vertical scales (including 'perceptual' A-weighted scales)
• Vertical scale calibrated as fraction of digital full scale ('FS') with currently-set mixer-settings etc.
• Choice of horizontal (frequency) scales, including a logarithmic 'perceptual' scale.
• NEW Spectrograph (waterfall) visualisation options (experimental new feature).

Features not yet implemented, but under consideration (roughly in order of likely implementation)

• Grid-line option on the spectral display
• Labelling/readout of precise frequency (and amplitude/energy) of prominent spectral peaks
• Stereo input, dual bargraph, choice of Left, Right, or both for frequency analysis
• User-selection of different transform sizes to trade-off time response and spectral resolution.
• Horizontal scroll option to allow close-up inspection of a narrow part of the spectrum.
• Time-averaged spectral displays
• ...

Download

Download: SpecAn_3v0.exe (529kB) new version 3.0 - October 2012.
By downloading this file, you consent to the standard disclaimer.

This applet doesn't require any installation, won't touch your Windows Registry, and won't install any DLLs. Just download the .EXE and run it. There's no bundled adware or unwanted toolbars. It'll even run straight off a USB memory stick if you want.

Created: May 2011
Last modified: 28 Oct 2012
Source: http://www.techmind.org/audio/specanaly.html