Low-cost real-time spectrographic analysis of sounds [abstract]

Gianni Pavan (1994). Low-cost real-time spectrographic analysis of sounds [abstract]. Bioacoustics, Volume 6 (1): 81

A low-cost Pc-based DSP workstation has been developed to allow high-quality hard disk direct recording and spectrographic analysis of audio signals. The system is based on software developed by the author and on a 16 bit ISA board, model Duetto made by Audiologic (Padova, ltaly). The board has two analog I/O channels with simultaneous sampling, 16 bit resolution with 90 dB signal/noise ratio, line input with selectable gain (0, 3, 6, 9 dB), sampling rate selectable between 8000, 9600, 11025, 16000, 22050, 32000, 44100 and 48000 sample/s, and on board high-precision digital anti-aliasing filters (64x oversampling). Hard disk recording can be performed in mono or stereo in full 16 bit linear mode or with two selectable ADPCM compression algorithms (compression ratios 2:1 and 4:1). The 16 bit linear format allows direct acquisition, hard disk recording and playback of audio signals with CD or DAT quality. Non-compressed audio files can then be edited, analyzed and/or played back to perform playback experiments. By means of a 486/66DX2 PC and a specific driver developed by Audiologic, recording or playback with synchronous real-time spectrographic analysis and display has been made possible on signals extending in frequency up to 21 kHz (48006 samples/s, single channel). By means of an external video converter, computer generated images can be converted to a standard video signal (PAI, or NTSC ) to be seen on conventional TV equipment or recorded on a video tape recorder. The DSPW, combined with conventional audio and video recording equipment now covers a wide range of needs typical of bioacoustical studies, such as low cost, IBM compatibility and great flexibility.