[TUHS] Bell-Era UNIX Audio/DSP Interfaces?

The sound situation in the UNIX world to me has always felt particularly fragmentary, with OSS offering some glimmer of hope but faltering under the long shadow of ALSA, with a hodge podge of PCM and other low level interfaces littered about other offerings. Given AT&T's involvement with the development of just about everything "sound over wires" for decades by the time UNIX comes along, one would suspect AT&T would be quite invested in standardizing interfaces for computers interacting with audio signals on copper wire. Indeed much of the ESS R&D was taking in analog telephone signals, digitizing them, and then acting on those digitized results before converting back to analog to send to the other end. Where this has me curious is if there were any efforts in Bell Labs, prior to other industry players having their hands on the steering wheel, to establish an abstract UNIX interface pattern for interacting with streams of converted audio signal. Of course modern formats didn't exist, but the general idea of PCM was well established, concepts like sampling rates, bit depths, etc. could be used in calculations to interpret and manipulate digitized audio streams. Any recollections? Was the landscape of signal processing solutions just so particular that trying to create a centralized interface didn't make sense at the time? Or was it a simple matter of priorities, with things like language development and system design taking center stage, leaving a dearth of resources to direct towards these sorts of matters? Was there ever a chance of seeing, say, the 5ESS handling of PCM, extended out to non-switching applications, or was that stuff firmly siloed over in the switching groups, having no influence on signal processing outside? - Matt G.