Conclusions

Sampling rate and sample resolution combine to determine the overall quality or fidelity of digitized sound. For digitized speech, sampling rates and sample resolutions typically range from low (telephone) quality values of 8000 Hz sampling rate with 8-bit samples (i.e., 4000 Hz Bandwidth and 48 dB dynamic range) to CD quality at a 44100 Hz sampling rate with 16-bit samples (22050 Hz Bandwidth and 96 dB dynamic range). Historically, much of the speech research using digital speech signals has been done with sampling rates of 10,000 to 12,000 Hz and 12-bit sample resolution. However, present day speech research typically involves use of sampling rates in the 16,000 to 22,050 range with sample resolutions of 16-bits. This change has taken place mostly for two reasons: hardware to sample sound at higher frequencies and bit resolutions has become much more affordable; and, even more crucially, storage space has become significantly less expensive. This latter factor is perhaps the most important since speech sampled at 22050 Hz and 16-bit resolution will require more than five times more space to store than would speech sampled at 8000 Hz and 8-bit resolution.