The base product use case has been to handle phone fidelity for many years. Think: legal dictation, retail digital recording hardware (phones), and medical transcription. Speech-to-text for recordings fed by a Telefunken U-47 is highly niche. :)
heh. It's not so much because of the microphones that the data sets are THAT narrow band - it's more phone bandwidth limitations. Even the cheapest electret and MEMS mics have pretty good freq response, far beyond 4khz (nyquist 8khz) this data set uses.
