The Psychoacoustics of Mono

As a child, my introduction to recorded music was via my family's monophonic all tube Craftsman hi-fi set-up, which included a 15-inch JBL D-130 mounted in a hole my father cut into the living room wall; the basement stairs behind the hole formed an immense infinite baffle speaker cabinet. (My father was very proud of this.) I've often thought about that sound over the years, and wondered if my memory of it was colored more by the rosy glow of nostalgia than the glow of KT-66s. I had the occasion to hook up and listen to a similar Craftsman set-up recently, and the sound was as I had remembered it—full, warm, rich, integrated, organic. . . .

Some time ago, I came to the conclusion that memory is monophonic. Now, clearly, we can all summon well-defined recollections of stereophonic placement—the intellectual cognizance and recollection that, say, Malcolm's guitar is on the right and Angus's is on the left, but when I speak of memory, I'm talking about internal mental playback—the way we play music back to ourselves in our own heads. When I re-run some favorite record in my head, even one that has some memorable panning or stereo placement, I still find that my internal playback is essentially monophonic. For me, this helps explain why music that I first heard monophonically retains a place in my memory with such immense clarity: the actual experience could be more closely approximated in mental playback. I've also speculated about the bandwidth of mental playback. Somehow, I sense that it is much narrower than the frequency range of our hearing. Without delving into biological anthropology, I surmise that it is probably approximate to the frequency range of the human voice. Similarly, the dynamic range of mental playback seems to be less than that of initial perception. Perhaps our brains use something analogous to data compression to store all those bad pop songs that re-emerge in our heads at inopportune moments, sometimes lodging there for hours at a time. Twenty or 30 or 40 years of musical memories is a lot of data, after all, and mental playback seems to work just fine at a limited bandwidth, with high- and low-pass filters sensibly engaged, a bit of compression and in glorious low-definition mono.